{"id":144,"date":"2019-09-18T19:40:36","date_gmt":"2019-09-18T19:40:36","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/chapter\/respiratory-system\/"},"modified":"2025-03-04T21:13:01","modified_gmt":"2025-03-04T21:13:01","slug":"respiratory-system","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/chapter\/respiratory-system\/","title":{"raw":"Respiratory System","rendered":"Respiratory System"},"content":{"raw":"<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\n<h2 class=\"textbox__title\"><em>Learning Objectives<\/em><\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"textbox__content\">\n<ul>\n \t<li>Examine the anatomy of the respiratory system<\/li>\n \t<li>Determine the main functions of the respiratory system<\/li>\n \t<li>Differentiate respiratory system medical terms and common abbreviations<\/li>\n \t<li>Recognize the medical specialties associated with the respiratory system<\/li>\n \t<li>Discover common diseases, disorders, and procedures related to the respiratory system<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<h2>Respiratory System Word Parts<\/h2>\nClick on prefixes, combining forms, and suffixes to reveal a list of word parts to memorize for the Respiratory System.\n\n&nbsp;\n\n[h5p id=\"71\"]\n<h2>Introduction to the Respiratory System<\/h2>\n<div class=\"textbox__content\">\n\nHow long you can hold your breath as you continue reading\u2026 How long can you do it? Chances are you are feeling uncomfortable already. A typical human cannot survive without breathing for more than three minutes, and even if you wanted to hold your breath longer, your [pb_glossary id=\"259\"]autonomic[\/pb_glossary] nervous system would take control. <span style=\"text-align: initial;font-size: 1em\">Although oxygen is critical for cells, it is the accumulation of carbon dioxide that primarily drives your need to breathe.<\/span>\n\n<\/div>\nThe major structures of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acid-base balance. Portions of the respiratory system are also used for non-vital functions, such as sensing odors, speech production, and for straining, such as coughing.\n\n&nbsp;\n\n[caption id=\"\" align=\"aligncenter\" width=\"420\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2020\/05\/2301_Major_Respiratory_Organs.jpg\" alt=\"Major respiratory structures. Image description available.\" width=\"420\" height=\"1625\"> <a id=\"Figure12.1\" href=\"\"><\/a>Figure 12.1 Major Respiratory Structures. The major respiratory structures span the nasal cavity to the diaphragm. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.1id\">[Image description.]<\/a>[\/caption]\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n\n<span class=\"tight\">If you hold your breath for longer than 3 minutes, your autonomic nervous system will take control.<\/span>\n\n<\/div>\n<\/div>\n<h3>Watch this video:<\/h3>\n<div class=\"textbox shaded\">\n\n[embed linkText=\"https:\/\/www.youtube.com\/watch?v=bHZsvBdUC2I\"]https:\/\/www.youtube.com\/watch?v=bHZsvBdUC2I[\/embed]\n\n<em>Media 12.1. <a href=\"https:\/\/youtu.be\/bHZsvBdUC2I\">Respiratory System, Part 1: Crash Course A&amp;P #31<\/a> [Online video]. Copyright 2015 by <a href=\"https:\/\/www.youtube.com\/user\/crashcourse\/about\">CrashCourse<\/a>.<\/em>\n\n<\/div>\n<h2>Practice Medical Terms Related to the Respiratory System<\/h2>\n<span style=\"float: none;background-color: transparent;color: #333333;cursor: text;font-family: 'Lora',serif;font-size: 16px;font-style: normal;font-variant: normal;font-weight: 400;letter-spacing: normal;text-align: left;text-decoration: none;text-indent: 0px;text-transform: none\">[h5p id=\"72\"]<\/span>\n<h2>Anatomy (Structures) of the Respiratory System<\/h2>\n<figure id=\"fig-ch23_01_01\"><\/figure>\n<h3 id=\"fs-id2061706\">The Nose and its Adjacent Structures<\/h3>\n<section id=\"fs-id1938446\"><section id=\"fs-id2486828\">\n<p id=\"fs-id2271107\">The major entrance and exit for the respiratory system is through the <strong>nose<\/strong>. When discussing the nose, it is helpful to divide it into two major sections:<\/p>\n\n<ul>\n \t<li>[pb_glossary id=\"301\"]external nose[\/pb_glossary]<\/li>\n \t<li>[pb_glossary id=\"546\"]internal nose[\/pb_glossary]<\/li>\n<\/ul>\nThe <strong>nares<\/strong> open into the nasal cavity, which is separated into left and right sections by the nasal septum (<a class=\"autogenerated-content\" href=\"#fig-ch23_01_03\">Figure 12.2<\/a>). The <strong>nasal septum<\/strong> is formed anteriorly by a portion of the [pb_glossary id=\"302\"]septal cartilage[\/pb_glossary] and posteriorly by the perpendicular plate of the ethmoid bone and the thin vomer bones.\n\n<span style=\"font-size: 1em\">Each lateral wall of the nasal cavity has three bony projections: <\/span><span style=\"font-size: 1em\">t<\/span><span style=\"font-size: 1em\">he inferior conchae are separate bones, and t<\/span><span style=\"font-size: 1em\">he superior and middle conchae are portions of the ethmoid bone. <\/span><span style=\"font-size: 1em\"><strong>Conchae<\/strong> increase the surface area of the nasal cavity, disrupting the flow of air as it enters the nose and causing air to bounce along the epithelium, where it is cleaned and warmed. <\/span><span style=\"font-size: 1em\">The conchae and meatuses trap water during exhalation preventing dehydration.<\/span>\n\n<span style=\"font-size: 1em\">The floor of the nasal cavity is composed of the<\/span><span style=\"font-size: 1em\"> [pb_glossary id=\"303\"]hard palate[\/pb_glossary] and the [pb_glossary id=\"304\"]soft palate[\/pb_glossary]. <\/span><span style=\"font-size: 1em\">Air exits the nasal cavities via the internal nares and moves into the pharynx.<\/span>\n<figure id=\"fig-ch23_01_03\">[caption id=\"\" align=\"aligncenter\" width=\"450\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2303_Anatomy_of_Nose-Pharynx-Mouth-Larynx.jpg\" alt=\"Diagram of the upper airway. Image description available.\" width=\"450\" height=\"1600\"> <a id=\"Figure12.2\" href=\"\"><\/a>Figure 12.2 Upper Airway. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.2id\">[Image description.]<\/a>[\/caption]<\/figure>\n<strong>Paranasal sinuses<\/strong> serve to warm and humidify incoming air and are lined with a mucosa which produces mucus. Paranasal sinuses are named for their associated bone:\n<ul>\n \t<li>frontal sinus<\/li>\n \t<li>maxillary sinus<\/li>\n \t<li>sphenoidal sinus<\/li>\n \t<li>ethmoidal sinus<\/li>\n<\/ul>\nThe nares and anterior portion of the nasal cavities are lined with mucous membranes, containing sebaceous glands and hair follicles that serve to prevent the passage of large debris, such as dirt, through the nasal cavity. An olfactory epithelium used to detect odors is found deeper in the nasal cavity.\n\nThe conchae, meatuses, and paranasal sinuses are lined by respiratory epithelium composed of pseudostratified ciliated columnar epithelium (<a class=\"autogenerated-content\" href=\"#fig-ch23_01_04\">Figure 12.3<\/a>). The epithelium contains specialized epithelial cells that produce mucus to trap debris. <span style=\"font-size: 1em\">The cilia of the respiratory epithelium help to remove mucus and debris with a constant beating motion, sweeping materials towards the throat to be swallowed. <\/span>\n\n<span style=\"font-size: 1em;text-align: initial\">This moist epithelium functions to warm and humidify incoming air. <\/span><span style=\"font-size: 1em;text-align: initial\">Capillaries located just beneath the nasal epithelium warm the air by convection. Serous and mucus-producing cells also secrete <strong>defensins<\/strong>, or immune cells that patrol the connective tissue providing additional protection.<\/span>\n<figure id=\"fig-ch23_01_04\"><figcaption><\/figcaption>[caption id=\"\" align=\"aligncenter\" width=\"500\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2304_Pseudostratified_Epithelium.jpg\" alt=\"Pseudostratified Ciliated Columnar Epithelium. Image description available.\" width=\"500\" height=\"1131\"> <a id=\"Figure12.3\" href=\"\"><\/a>Figure 12.3 Pseudostratified Ciliated Columnar Epithelium. Respiratory epithelium is pseudostratified ciliated columnar epithelium. Seromucous glands provide lubricating mucus. LM \u00d7 680. (Micrograph provided by the Regents of University of Michigan Medical School \u00a9 2012). From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.3id\">[Image description.]<\/a>[\/caption]<\/figure>\n<div id=\"fs-id2103496\" class=\"note anatomy interactive um\">\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n\n<span class=\"tight\">Cold air slows the movement of cilia that may result in the accumulation of mucus, leading to [pb_glossary id=\"293\"]rhinorrhea[\/pb_glossary] during cold weather.<\/span>\n\n<\/div>\n<\/div>\n<h3 id=\"fs-id1983622\">Pharynx<\/h3>\n<\/div>\n<\/section><section id=\"fs-id2419331\">\n<p id=\"fs-id2020239\">The [pb_glossary id=\"307\"]pharynx[\/pb_glossary] is divided into three major regions: the <strong>nasopharynx<\/strong>, the <strong>oropharynx<\/strong>, and the <strong>laryngopharynx<\/strong> (see <a class=\"autogenerated-content\" href=\"#fig-ch23_01_05\">Figure 12.4<\/a>).<\/p>\n\n<figure id=\"fig-ch23_01_05\"><figcaption><\/figcaption>[caption id=\"\" align=\"aligncenter\" width=\"475\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2305_Divisions_of_the_Pharynx.jpg\" alt=\"Divisions of the pharynx. Image description available.\" width=\"475\" height=\"1496\"> <a id=\"Figure12.4\" href=\"\"><\/a>Figure 12.4 Divisions of the Pharynx. The pharynx is divided into three regions: the nasopharynx, the oropharynx, and the laryngopharynx. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.4id\">[Image description.]<\/a>[\/caption]<\/figure>\n<p id=\"fs-id2591817\">At the top of the <strong>nasopharynx<\/strong> are the pharyngeal tonsils. The function of the [pb_glossary id=\"317\"]pharyngeal[\/pb_glossary] tonsil is not well understood, but it contains a rich supply of [pb_glossary id=\"705\"]lymphocytes[\/pb_glossary] and is covered with ciliated epithelium that traps and destroys invading pathogens that enter during inhalation. The pharyngeal tonsils are large in children but tend to regress with age and may even disappear. The [pb_glossary id=\"310\"]uvula[\/pb_glossary] and [pb_glossary id=\"304\"]soft palate[\/pb_glossary] move like a pendulum during swallowing, swinging upward to close off the nasopharynx to prevent ingested materials from entering the nasal cavity. Auditory (Eustachian) tubes that connect to each middle ear cavity open into the nasopharynx. This connection is why colds often lead to ear infections.<\/p>\n<p id=\"fs-id2641568\">The <strong>oropharynx<\/strong> is bordered superiorly by the [pb_glossary id=\"308\"]nasopharynx[\/pb_glossary] and anteriorly by the oral cavity. The [pb_glossary id=\"311\"]oropharynx[\/pb_glossary] contains two distinct sets of tonsils:<\/p>\n\n<ul>\n \t<li>The palatine tonsils.\n<ul>\n \t<li>A palatine tonsil is one of a pair of structures located laterally in the oropharynx in the area of the [pb_glossary id=\"312\"]fauces[\/pb_glossary].<\/li>\n<\/ul>\n<\/li>\n \t<li>The lingual tonsils.\n<ul>\n \t<li>The [pb_glossary id=\"318\"]lingual[\/pb_glossary] tonsil is located at the base of the tongue.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\nSimilar to the pharyngeal tonsil, the palatine and [pb_glossary id=\"318\"]lingual[\/pb_glossary] tonsils are composed of lymphoid tissue, and trap and destroy pathogens entering the body through the oral or nasal cavities.\n<p id=\"fs-id1639121\">The <strong>laryngopharynx<\/strong> is [pb_glossary id=\"321\"]inferior[\/pb_glossary] to the oropharynx and [pb_glossary id=\"322\"]posterior[\/pb_glossary] to the larynx. It continues the route for ingested material and air until its [pb_glossary id=\"321\"]inferior[\/pb_glossary] end, where the digestive and respiratory systems diverge. The stratified squamous epithelium of the oropharynx is continuous with the laryngopharynx. Anteriorly, the laryngopharynx opens into the larynx, whereas [pb_glossary id=\"398\"]posteriorly[\/pb_glossary], it enters the esophagus.<\/p>\n\n<\/section><section>\n<h3>Larynx<\/h3>\n<p id=\"fs-id2874398\">The structure of the [pb_glossary id=\"313\"]larynx[\/pb_glossary] is formed by several pieces of cartilage. Three large cartilage pieces form the major structure of the larynx.<\/p>\n\n<ul>\n \t<li>Thyroid cartilage (anterior):\n<ul>\n \t<li>The thyroid cartilage is the largest piece of cartilage that makes up the larynx. The thyroid cartilage consists of the [pb_glossary id=\"314\"]laryngeal[\/pb_glossary] prominence, or \u201cAdam\u2019s apple,\u201d which tends to be more prominent in males.<\/li>\n<\/ul>\n<\/li>\n \t<li>Epiglottis (superior):\n<ul>\n \t<li>Three smaller, paired cartilages\u2014the arytenoids, corniculates, and cuneiforms\u2014attach to the [pb_glossary id=\"315\"]epiglottis[\/pb_glossary] and the vocal cords and muscle that help move the vocal cords to produce speech.<\/li>\n<\/ul>\n<\/li>\n \t<li>Cricoid cartilage (inferior):\n<ul>\n \t<li>The thick cricoid cartilage forms a ring, with a wide posterior region and a thinner anterior region.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<figure id=\"fig-ch23_01_06\"><figcaption><\/figcaption>[caption id=\"\" align=\"aligncenter\" width=\"450\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2306_The_Larynx.jpg\" alt=\"Anterior and right lateral view of the larynx. Image description available.\" width=\"450\" height=\"1673\"> <a id=\"Figure12.5\" href=\"\"><\/a>Figure 12.5 Larynx. The larynx extends from the laryngopharynx and the hyoid bone to the trachea. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.5id\">[Image description.]<\/a>[\/caption]<\/figure>\n<p id=\"fs-id2637383\">When the [pb_glossary id=\"315\"]epiglottis[\/pb_glossary] is in the \u201cclosed\u201d position, the unattached end of the epiglottis rests on the [pb_glossary id=\"316\"]glottis[\/pb_glossary]. A vestibular fold, or false vocal cord, is one of a pair of folded sections of mucous membrane. A true vocal cord is one of the white, membranous folds attached by muscle to the thyroid and arytenoid cartilages of the larynx on their outer edges. The inner edges of the true vocal cords are free, allowing oscillation to produce sound.<\/p>\nThe act of swallowing causes the pharynx and larynx to lift upward, allowing the pharynx to expand and the epiglottis of the larynx to swing downward, closing the opening to the trachea. These movements produce a larger area for food to pass through, while preventing food and beverages from entering the trachea.\n<figure id=\"fig-ch23_01_07\"><figcaption><\/figcaption>[caption id=\"\" align=\"aligncenter\" width=\"450\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2307_Cartilages_of_the_Larynx.jpg\" alt=\"Cross-section of the vocal cords. Image description available.\" width=\"450\" height=\"1133\"> <a id=\"Figure12.6\" href=\"\"><\/a>Figure 12.6 Vocal Cords. The true vocal cords and vestibular folds of the larynx are viewed inferiorly from the laryngopharynx. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.6id\">[Image description.]<\/a>[\/caption]<\/figure>\n<p id=\"fs-id2338748\">Similar to the nasal cavity and nasopharynx, this specialized epithelium produces mucus to trap debris and pathogens as they enter the trachea. The cilia beat the mucus upward towards the laryngopharynx, where it can be swallowed down the esophagus.<\/p>\n&nbsp;\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n\n<span class=\"tight\" style=\"direction: ltr\">Folds of the true vocal cords differ between individuals resulting in voices with different pitches.<\/span>\n\n<\/div>\n<\/div>\n<\/section><section id=\"fs-id2718252\">\n<h3>Trachea<\/h3>\n<p id=\"fs-id2058199\">The [pb_glossary id=\"319\"]trachea[\/pb_glossary] is formed by 16 to 20 stacked, C-shaped pieces of hyaline cartilage that are connected by dense connective tissue. The trachealis muscle and elastic connective tissue together form the [pb_glossary id=\"320\"]fibroelastic membrane[\/pb_glossary]. The fibroelastic membrane allows the trachea to stretch and expand slightly during inhalation and exhalation, whereas the rings of cartilage provide structural support and prevent the trachea from collapsing. The trachealis muscle can be contracted to force air through the trachea during exhalation. The trachea is lined with pseudostratified ciliated columnar epithelium, which is continuous with the larynx. The esophagus borders the trachea posteriorly.<\/p>\n\n<figure id=\"fig-ch23_01_08\"><figcaption><\/figcaption>[caption id=\"\" align=\"aligncenter\" width=\"560\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2308_The_Trachea.jpg\" alt=\"Trachea and lungs. Image description available.\" width=\"560\" height=\"1430\"> <a id=\"Figure12.7\" href=\"\"><\/a>Figure 12.7 Trachea. (a) The tracheal tube is formed by stacked, C-shaped pieces of hyaline cartilage. (b) The layer visible in this cross-section of tracheal wall tissue between the hyaline cartilage and the lumen of the trachea is the mucosa, which is composed of pseudostratified ciliated columnar epithelium that contains goblet cells. LM \u00d7 1220. (Micrograph provided by the Regents of University of Michigan Medical School \u00a9 2012). From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.7id\">[Image description.]<\/a>[\/caption]<\/figure>\n<\/section><section id=\"fs-id2654941\">\n<h3>Bronchial Tree<\/h3>\n<p id=\"fs-id2033350\">The trachea branches into the right and left primary bronchi at the [pb_glossary id=\"341\"]carina[\/pb_glossary]. These bronchi are also lined by pseudostratified ciliated columnar epithelium containing mucus-producing goblet cells (<a class=\"autogenerated-content\" href=\"#fig-ch23_01_08\">Figure 12.7b<\/a>). The carina is a raised structure that contains specialized nervous tissue that induces violent coughing if a foreign body, such as food, is present. Rings of cartilage, similar to those of the trachea, support the structure of the bronchi and prevent their collapse. The primary bronchi enter the lungs at the [pb_glossary id=\"323\"]hilum[\/pb_glossary]. The bronchi continue to branch into a bronchial tree. A bronchial tree (or respiratory tree) is the collective term used for these multiple-branched bronchi. The main function of the bronchi, like other conducting zone structures, is to provide a passageway for air to move into and out of each lung. The mucous membrane traps debris and pathogens.<\/p>\n<p id=\"fs-id2138728\">A bronchiole branches from the tertiary bronchi. Bronchioles, which are about 1 mm in diameter, further branch until they become the tiny terminal bronchioles, which lead to the structures of gas exchange. There are more than 1,000 terminal bronchioles in each lung. The muscular walls of the bronchioles do not contain cartilage like those of the bronchi. This muscular wall can change the size of the tubing to increase or decrease airflow through the tube.<\/p>\n\n<\/section><\/section><section id=\"fs-id2875750\">\n<h3>Respiratory Zone<\/h3>\n<p id=\"fs-id2757673\">In contrast to the [pb_glossary id=\"300\"]conducting zone[\/pb_glossary], the [pb_glossary id=\"306\"]respiratory zone[\/pb_glossary] includes structures that are directly involved in gas exchange. The respiratory zone begins where the terminal bronchioles join a respiratory bronchiole, the smallest type of bronchiole (see <a class=\"autogenerated-content\" href=\"#fig-ch23_01_09\">Figure 12.8<\/a>), which then leads to an alveolar duct, opening into a cluster of alveoli.<\/p>\n\n<figure id=\"fig-ch23_01_09\"><figcaption><\/figcaption>[caption id=\"\" align=\"aligncenter\" width=\"525\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2309_The_Respiratory_Zone.jpg\" alt=\"The respiratory zone. Image description available. \" width=\"525\" height=\"1671\"> <a id=\"Figure12.8\" href=\"\"><\/a>Figure 12.8 Respiratory Zone. Bronchioles lead to alveolar sacs in the respiratory zone, where gas exchange occurs. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.8id\">[Image description.]<\/a>[\/caption]<\/figure>\n<section id=\"fs-id2918858\">\n<h3>Alveoli<\/h3>\n<p id=\"fs-id1980157\">An [pb_glossary id=\"324\"]alveolar duct[\/pb_glossary] opens into a cluster of alveoli. An alveolus is one of the many small, grape-like sacs that are attached to the alveolar ducts. An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange. An alveolus is approximately 200 \u03bcm in diameter with elastic walls that allow the alveolus to stretch during air intake, which greatly increases the surface area available for gas exchange. Alveoli are connected to their neighbors by alveolar pores, which help maintain equal air pressure throughout the alveoli and lung (see <a class=\"autogenerated-content\" href=\"#fig-ch23_01_10\">Figure 12.9<\/a>).<\/p>\n\n<figure id=\"fig-ch23_01_10\"><figcaption><\/figcaption>[caption id=\"\" align=\"aligncenter\" width=\"560\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2310_Structures_of_the_Respiratory_Zone.jpg\" alt=\"Structures of the respiratory zone. Image description available.\" width=\"560\" height=\"1155\"> <a id=\"Figure12.9\" href=\"\"><\/a>Figure 12.9 Structures of the Respiratory Zone. (a) The alveolus is responsible for gas exchange. (b) A micrograph shows the alveolar structures within lung tissue. LM \u00d7 178. (Micrograph provided by the Regents of University of Michigan Medical School \u00a9 2012). From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.9id\">[Image description.]<\/a>[\/caption]<\/figure>\n<div id=\"fs-id1895080\" class=\"note anatomy interactive\">\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Concept Check<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n \t<li>What are the components of the <strong>bronchial<\/strong> tree?<\/li>\n \t<li>What is the purpose of<strong> cilia<\/strong>?<\/li>\n \t<li>Where does<strong> gas<\/strong> exchange take place?<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h3 id=\"fs-id2817577\">Gross Anatomy of the Lungs<\/h3>\n<\/div>\n<\/section><\/section><section id=\"fs-id2517312\" class=\"summary\"><section id=\"fs-id2644915\">\n<p id=\"fs-id2627237\">The lungs are pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi; on the inferior surface, the lungs are bordered by the [pb_glossary id=\"547\"]diaphragm[\/pb_glossary]. The lungs are enclosed by the pleurae, which are attached to the mediastinum. The right lung is shorter and wider than the left lung, and the left lung occupies a smaller volume than the right. The [pb_glossary id=\"339\"]cardiac notch[\/pb_glossary] allows space for the heart (see <a class=\"autogenerated-content\" href=\"#fig-ch23_02_01\">Figure 12.10<\/a>). The apex of the lung is the superior region, whereas the base is the opposite region near the diaphragm. The costal surface of the lung borders the ribs. The mediastinal surface faces the midline.<\/p>\n\n<figure id=\"fig-ch23_02_01\">[caption id=\"\" align=\"aligncenter\" width=\"430\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2312_Gross_Anatomy_of_the_Lungs.jpg\" alt=\"Gross anatomy of the lungs. Image description available.\" width=\"430\" height=\"1304\"> <a id=\"Figure12.10\" href=\"\"><\/a>Figure 12.10 Gross Anatomy of the Lungs. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.10id\">[Image description.]<\/a>[\/caption]<\/figure>\n<p id=\"fs-id2717313\">Each lung is composed of smaller units called lobes. Fissures separate these lobes from each other. The right lung consists of three lobes: the superior, middle, and inferior lobes. The left lung consists of two lobes: the superior and inferior lobes. A pulmonary lobule is a subdivision formed as the bronchi branch into bronchioles. Each lobule receives its own large bronchiole that has multiple branches. An interlobular septum is a wall, composed of connective tissue, which separates lobules from one another.<\/p>\n\n<\/section><section><\/section>\n<h3>Can you correctly label the respiratory system structures?<\/h3>\n<section>[h5p id=\"73\"]<\/section>\n<h2>Physiology (Function) of the Respiratory System<\/h2>\n<section><section id=\"fs-id2795878\">\n<h3>Blood Supply<\/h3>\n<p id=\"fs-id2144132\">The major function of the lungs is to perform gas exchange, which requires blood from the pulmonary circulation.<\/p>\n\n<ul>\n \t<li style=\"text-align: left\">This blood supply contains deoxygenated blood and travels to the lungs where [pb_glossary id=\"421\"]erythrocytes[\/pb_glossary] pick up oxygen to be transported to tissues throughout the body.<\/li>\n \t<li style=\"text-align: left\">The [pb_glossary id=\"340\"]pulmonary artery[\/pb_glossary] carries deoxygenated, arterial blood to the alveoli.<\/li>\n \t<li style=\"text-align: left\">The pulmonary artery branches multiple times as it follows the bronchi, and each branch becomes progressively smaller in diameter.<\/li>\n \t<li style=\"text-align: left\">One arteriole and an accompanying venule supply and drain one pulmonary lobule. As they near the alveoli, the pulmonary arteries become the pulmonary capillary network.<\/li>\n \t<li style=\"text-align: left\">The pulmonary capillary network consists of tiny vessels with very thin walls that lack smooth muscle fibers.<\/li>\n \t<li style=\"text-align: left\">The capillaries branch and follow the bronchioles and structure of the alveoli. It is at this point that the capillary wall meets the alveolar wall, creating the respiratory membrane.<\/li>\n \t<li style=\"text-align: left\">Once the blood is oxygenated, it drains from the alveoli by way of multiple pulmonary veins, which exit the lungs through the [pb_glossary id=\"323\"]hilum[\/pb_glossary].<\/li>\n<\/ul>\n<\/section>\n<h3>Nervous Innervation<\/h3>\n<p id=\"fs-id2179965\">The blood supply of the lungs plays an important role in gas exchange and serves as a transport system for gases throughout the body. Innervation by both the [pb_glossary [pb_glossary id=\"548\"]parasympathetic[\/pb_glossary] and [pb_glossary id=\"337\"]sympathetic nervous systems[\/pb_glossary] provides an important level of control through dilation and constriction of the airway.<\/p>\n\n<ul>\n \t<li>The parasympathetic system causes bronchoconstriction.<\/li>\n \t<li>The sympathetic nervous system stimulates bronchodilation.<\/li>\n<\/ul>\nReflexes such as coughing, and the ability of the lungs to regulate oxygen and carbon dioxide levels, also result from [pb_glossary id=\"259\"]autonomic[\/pb_glossary] nervous system control. Sensory nerve fibers arise from the vagus nerve, and from the second to fifth thoracic ganglia. The pulmonary plexus is a region on the lung root formed by the entrance of the nerves at the hilum. The nerves then follow the bronchi in the lungs and branch to innervate muscle fibers, glands, and blood vessel<span style=\"font-size: 1em\">s.<\/span>\n\n<\/section><section id=\"fs-id2293350\">\n<h3>Pleura of the Lungs<\/h3>\nEach lung is enclosed within a cavity that is surrounded by the pleura. The pleura (plural = pleurae) is a serous membrane that surrounds the lung. The right and left pleurae, which enclose the right and left lungs, respectively, are separated by the mediastinum.\n\nThe pleurae consist of two layers:\n<ol>\n \t<li>The <strong>visceral pleura<\/strong> is the layer that is superficial to the lungs and extends into and lines the lung fissures (see <a class=\"autogenerated-content\" href=\"#fig-ch23_02_02\">Figure 12.11<\/a>).<\/li>\n \t<li>The <strong>parietal pleura<\/strong> is the outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm.<\/li>\n<\/ol>\nThe visceral and parietal pleurae connect to each other at the [pb_glossary id=\"323\"]hilum[\/pb_glossary]. The pleural cavity is the space between the visceral and parietal layers.\n<figure id=\"fig-ch23_02_02\">[caption id=\"\" align=\"aligncenter\" width=\"440\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2313_The_Lung_Pleurea.jpg\" alt=\"Parietal and visceral pleurae of the lungs. Image description available.\" width=\"440\" height=\"1450\"> <a id=\"Figure12.11\" href=\"\"><\/a>Figure 12.11 Parietal and Visceral Pleurae of the Lungs. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.11id\">[Image description.]<\/a>[\/caption]<\/figure>\n<p id=\"fs-id2078585\">The pleurae perform two major functions:<\/p>\n\n<ol>\n \t<li><strong>Produce pleural fluid<\/strong> that lubricates surfaces, reduces friction to prevent trauma during breathing, and creates surface tension that helps maintain the position of the lungs against the thoracic wall. This adhesive characteristic of the pleural fluid causes the lungs to enlarge when the thoracic wall expands during ventilation, allowing the lungs to fill with air.<\/li>\n \t<li>The pleurae also <strong>create a division<\/strong> between major organs that prevents interference due to the movement of the organs, while preventing the spread of infection.<\/li>\n<\/ol>\n<div id=\"fs-id2239873\" class=\"note anatomy everyday\">\n<h3>Pulmonary Ventilation<\/h3>\n<\/div>\n<\/section><section id=\"fs-id2773018\" class=\"summary\">\n<p id=\"fs-id2241368\">The difference in pressures drives pulmonary ventilation because air flows down a pressure gradient, that is, air flows from an area of higher pressure to an area of lower pressure.<\/p>\n\n<ul>\n \t<li>Air flows into the lungs largely due to a difference in pressure; atmospheric pressure is greater than intra-alveolar pressure, and intra-alveolar pressure is greater than intrapleural pressure.<\/li>\n \t<li>Air flows out of the lungs during expiration based on the same principle; pressure within the lungs becomes greater than the atmospheric pressure.<\/li>\n<\/ul>\n<p id=\"fs-id1882180\">Pulmonary ventilation comprises two major steps: inspiration and expiration. [pb_glossary id=\"342\"]Inspiration[\/pb_glossary] is the process of having air enter the lungs and expiration is the process of expelling air from the lungs (<a class=\"autogenerated-content\" href=\"#fig-ch23_03_03\">Figure 12.12<\/a>). <span style=\"font-size: 1em\">A respiratory cycle is one sequence of inspiration and expiration.<\/span><\/p>\nTwo muscle groups are used during <strong>normal inspiration<\/strong>: t<span style=\"font-size: 1em\">he diaphragm and the external intercostal muscles. Additional muscles can be used if a bigger breath is required. <\/span>\n<ul>\n \t<li><span style=\"font-size: 1em\">The diaphragm contracts, it moves inferiorly toward the abdominal cavity, creating a larger thoracic cavity and more space for the lungs.<\/span><\/li>\n \t<li>The external intercostal muscles contract and move the ribs upward and outward, causing the rib cage to expand, which increases the volume of the thoracic cavity.<\/li>\n<\/ul>\nDue to the adhesive force of the pleural fluid, the expansion of the thoracic cavity forces the lungs to stretch and expand as well. This increase in volume leads to a decrease in intra-alveolar pressure, creating a pressure lower than atmospheric pressure. As a result, a pressure gradient is created that drives air into the lungs.\n<figure id=\"fig-ch23_03_03\">[caption id=\"\" align=\"aligncenter\" width=\"450\"]<img src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2316_Inspiration_and_Expiration.jpg\" alt=\"Inspiration and expiration process diagram. Image description available.\" width=\"450\" height=\"1422\"> <a id=\"Figure12.12\" href=\"\"><\/a>Figure 12.12 Inspiration and Expiration. Inspiration and expiration occur due to the expansion and contraction of the thoracic cavity, respectively. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.12id\">[Image description.]<\/a>[\/caption]<\/figure>\n<p id=\"fs-id2453488\">The process of <strong>normal expiration <\/strong>is passive, meaning that energy is not required to push air out of the lungs.<\/p>\n\n<ul>\n \t<li>The elasticity of the lung tissue causes the lung to recoil, as the diaphragm and intercostal muscles relax following inspiration.<\/li>\n \t<li>The thoracic cavity and lungs decrease in volume, causing an increase in intrapulmonary pressure. The intrapulmonary pressure rises above atmospheric pressure, creating a pressure gradient that causes air to leave the lungs.<\/li>\n<\/ul>\n<p id=\"fs-id2327717\">There are different types, or modes, of breathing that require a slightly different process to allow inspiration and expiration:<\/p>\n\n<ul>\n \t<li><strong> Quiet breathing<\/strong>, also known as [pb_glossary id=\"218\"]eupnea[\/pb_glossary], is a mode of breathing that occurs at rest and does not require the cognitive thought of the individual. During quiet breathing, the diaphragm and external intercostals must contract.<\/li>\n \t<li><strong>Diaphragmatic breathing<\/strong>, also known as deep breathing, requires the diaphragm to contract. As the diaphragm relaxes, air passively leaves the lungs.<\/li>\n \t<li><strong>Costal<\/strong> <strong>breathing<\/strong>, also known as a shallow breath, requires contraction of the intercostal muscles. As the intercostal muscles relax, air passively leaves the lungs.<\/li>\n \t<li><strong>Forced breathing<\/strong>, also known as [pb_glossary id=\"344\"]hyperpnea[\/pb_glossary], is a mode of breathing that can occur during exercise or actions that require the active manipulation of breathing, such as singing.\n<ul>\n \t<li>During forced breathing, inspiration and expiration both occur due to muscle contractions. In addition to the contraction of the diaphragm and intercostal muscles, other accessory muscles must also contract.\n<ul>\n \t<li>During <strong>forced inspiration<\/strong>, muscles of the neck contract and lift the thoracic wall, increasing lung volume.<\/li>\n \t<li>During <strong>forced expiration<\/strong>, accessory muscles of the abdomen contract, forcing abdominal organs upward against the diaphragm. This helps to push the diaphragm further into the thorax, pushing more air out. In addition, accessory muscles help to compress the rib cage, which also reduces the volume of the thoracic cavity.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Concept Check<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n \t<li>Breathing normally, place your hand on your stomach and take in one full respiratory cycle.\n<ul>\n \t<li>What type of breathing are you doing?<\/li>\n<\/ul>\n<\/li>\n \t<li>Keeping your hand on your stomach, take in one large breath and exhale.\n<ul>\n \t<li>What type of breathing are you doing?<\/li>\n<\/ul>\n<\/li>\n \t<li>Complete 10 jumping jacks. Once completed, place your hand on your stomach and take in one full respiratory cycle.\n<ul>\n \t<li>What type of breathing are you doing?<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/section><section id=\"fs-id2308596\">\n<div id=\"fs-id2005739\" class=\"note anatomy interactive\">\n<h3 id=\"fs-id1368768\">Respiratory Rate and Control of Ventilation<\/h3>\n<\/div>\n<\/section><section id=\"fs-id2129879\">\n<p id=\"fs-id2278288\">Breathing usually occurs without thought, although at times you can consciously control it, such as when you swim under water, sing a song, or blow bubbles. The respiratory rate is the total number of breaths that occur each minute. Respiratory rate can be an important indicator of disease, as the rate may increase or decrease during an illness or in a disease condition. The respiratory rate is controlled by the respiratory center located within the medulla oblongata in the brain, which responds primarily to changes in carbon dioxide, oxygen, and pH levels in the blood.<\/p>\n<p id=\"fs-id2100118\">The normal respiratory rate of a child decreases from birth to adolescence:<\/p>\n\n<ul>\n \t<li>A child under 1 year of age has a normal respiratory rate between 30 and 60 breaths per minute.<\/li>\n \t<li>By the time a child is about 10 years old, the normal rate is closer to 18 to 30.<\/li>\n \t<li>By adolescence, the normal respiratory rate is similar to that of adults, 12 to 18 breaths per minute.<\/li>\n<\/ul>\n<\/section><section id=\"fs-id2129879\">\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n\nRespiratory rate is the total number of breaths that occur each minute.\n\n<\/div>\n<\/div>\n<h3>Watch this video:<\/h3>\n<div class=\"textbox shaded\">\n\n[embed]https:\/\/www.youtube.com\/embed\/Cqt4LjHnMEA[\/embed]\n\n<em>Media 12.1. <a href=\"https:\/\/youtu.be\/Cqt4LjHnMEA\">Respiratory System, Part 2: Crash Course A&amp;P #32<\/a> [Online video]. Copyright 2015 by <a href=\"https:\/\/www.youtube.com\/channel\/UCX6b17PVsYBQ0ip5gyeme-Q\">CrashCourse<\/a>.<\/em>\n\n<\/div>\n<h2>Practice Terms Related to the Respiratory System<\/h2>\n&nbsp;\n\n[h5p id=\"74\"]\n<h2>Common Abbreviations for the Respiratory System<\/h2>\nMany terms and phrases related to the respiratory system are abbreviated. Learn these common abbreviations by expanding the list below.\n\n&nbsp;\n\n[h5p id=\"75\"]\n\n<\/section><section id=\"fs-id2129879\"><section id=\"fs-id2167754\">\n<h2>Diseases and Disorders of the Respiratory System<\/h2>\nA variety of diseases can affect the respiratory system, such as asthma, emphysema, chronic obstructive pulmonary disorder (COPD), and lung cancer. All of these conditions affect the gas exchange process and result in labored breathing and other difficulties.\n<h3>The Effects of Second-Hand Tobacco Smoke<\/h3>\n<\/section><section id=\"fs-id2167754\">The burning of a tobacco cigarette creates multiple chemical compounds that are released through mainstream smoke, which is inhaled by the smoker, and through sidestream smoke, which is the smoke that is given off by the burning cigarette. <strong>Second-hand smoke<\/strong>, which is a combination of sidestream smoke and the mainstream smoke that is exhaled by the smoker, has been demonstrated by numerous scientific studies to cause disease. At least 40 chemicals in sidestream smoke have been identified that negatively impact human health, leading to the development of cancer or other conditions, such as immune system dysfunction, liver toxicity, cardiac [pb_glossary id=\"411\"]arrhythmias[\/pb_glossary], pulmonary [pb_glossary id=\"238\"]edema[\/pb_glossary], and neurological dysfunction. Tobacco and second-hand smoke are considered to be [pb_glossary id=\"274\"]carcinogenic[\/pb_glossary]<span style=\"font-size: 1em\">. Exposure to second-hand smoke can cause lung cancer in individuals who are not tobacco users themselves.<\/span><\/section><section><\/section>\n<ul>\n \t<li>It is estimated that the risk of developing lung cancer is increased by up to 30% in nonsmokers who live with an individual who smokes in the house, as compared to nonsmokers who are not regularly exposed to second-hand smoke.<\/li>\n \t<li>Children who live with an individual who smokes inside the home have a larger number of lower respiratory infections, which are associated with hospitalizations, and higher risk of sudden infant death syndrome (SIDS). Second-hand smoke in the home has also been linked to a greater number of ear infections in children, as well as worsening symptoms of asthma.<\/li>\n<\/ul>\n<section><\/section><section><\/section><\/section><\/section>\n<div class=\"note anatomy disorders\">\n<h3>Chronic Obstructive Pulmonary Disease (COPD)<\/h3>\nCOPD is a term used to represent a number of respiratory diseases, including chronic bronchitis and emphysema. COPD is a [pb_glossary id=\"243\"]chronic[\/pb_glossary] condition with most symptoms appearing in middle-aged or older adults. Signs and symptoms include shortness of breath, cough, and sputum production. There is no cure for COPD. Shortness of breath may be controlled with [pb_glossary id=\"358\"]bronchodilators[\/pb_glossary]. The best plan is to avoid triggers and getting sick. Clients with COPD are advised to avoid people who are sick, get vaccinated against influenza and pneumococcal pneumonia, and reduce their exposure to pollution and cigarette smoke. <span style=\"font-size: 1em\">While there are several risk factors, as many as 75% <\/span>of cases are associated with cigarette smoking <span style=\"text-align: initial;font-size: 1em\">(National Heart, Lung, and Blood Institute, n.d.)<\/span><span style=\"font-size: 1em\">. <\/span><span style=\"text-align: initial;font-size: 1em\">To learn more about COPD, visit the <a href=\"https:\/\/www.nhlbi.nih.gov\/health-topics\/copd\">National Heart, Lung, and Blood Institute's web page<\/a>.<\/span>\n<h3>Asthma<\/h3>\n<\/div>\n<div id=\"fs-id2279663\" class=\"note anatomy diseases\">\n\nAsthma is a chronic disease characterized by inflammation, [pb_glossary id=\"238\"]edema[\/pb_glossary] of the airway, and bronchospasms which can inhibit air from entering the lungs. Bronchospasms can lead to an \u201casthma attack.\u201d An attack may be triggered by environmental factors such as dust, pollen, pet hair, or dander, changes in the weather, mold, tobacco smoke, and respiratory infections, or by exercise and stress.\n\nSigns and symptoms of an asthma attack involve coughing, shortness of breath, wheezing, and tightness of the chest. Symptoms of a severe asthma attack require immediate medical attention and may include [pb_glossary id=\"295\"]dyspnea[\/pb_glossary] that results in [pb_glossary id=\"345\"]cyanotic[\/pb_glossary] lips or face, confusion, drowsiness, a rapid pulse, sweating, and severe anxiety. The severity of the condition, frequency of attacks, and identified triggers influence the type of medication that an individual may require. Longer-term treatments are used for those with more severe asthma. Short-term, fast-acting drugs that are used to treat an asthma attack are typically administered via an inhaler. For young children or individuals who have difficulty using an inhaler, asthma medications can be administered via a nebulizer.\n<h3>Lung Cancer<\/h3>\n<\/div>\nLung cancer is a leading cause of cancer death among men and women. Smoking is the most significant risk factor for lung cancer, with 90% of cases in men and 80% of cases in women attributed to tobacco smoking. Signs and symptoms may include shortness of breath, wheezing, blood in the mucus, hoarseness, and trouble swallowing (MedlinePlus, n.d.).\n\nThere are two types of lung cancer, <strong>small cell lung cancer (SCLC)<\/strong> and non-small cell lung cancer (NSCLC). Both cancers occur when [pb_glossary id=\"626\"]malignant[\/pb_glossary] cells form in the tissues of the lung. If [pb_glossary id=\"571\"]metastasis[\/pb_glossary] occurs, lung cancer cells spread to other parts of the body. Treatment will depend on the type of lung cancer and the stage at diagnosis. Treatments may include surgery, chemotherapy, targeted therapy, immunotherapy, and radiation therapy (National Cancer Institute, 2021a, 2021b).\n<div id=\"fs-id1895080\" class=\"note anatomy interactive\"><section id=\"fs-id2129879\"><section id=\"fs-id2167754\">\n<div id=\"fs-id1273237\" class=\"note anatomy disorders\">\n<h3 id=\"fs-id1983836\">Sleep Apnea<\/h3>\nSleep apnea is a [pb_glossary id=\"243\"]chronic[\/pb_glossary] disorder that occurs in children and adults. It is characterized by the cessation of breathing during sleep. These episodes may last for several seconds or several minutes, and may differ in the frequency with which they are experienced. Sleep apnea leads to poor sleep. Signs and symptoms include fatigue, evening napping, irritability, memory problems, morning headaches, and excessive snoring. A diagnosis of sleep apnea is usually done during a sleep study, where the patient is monitored in a sleep laboratory for several nights. <span style=\"text-align: initial;font-size: 1em\">Treatment of sleep apnea commonly includes the use of a device called a <\/span><strong style=\"text-align: initial;font-size: 1em\">continuous positive airway pressure (CPAP) machine<\/strong><span style=\"text-align: initial;font-size: 1em\"> during sleep. The CPAP machine has a mask that covers the nose, or the nose and mouth, and forces air into the airway at regular intervals. This pressurized air can help to gently force the airway to remain open, allowing more normal ventilation to occur.<\/span>\n\n<\/div>\n<\/section><\/section>\n<h2>Medical Terms in Context<\/h2>\n[h5p id=\"76\"]\n\n[h5p id=\"77\"]\n\n[h5p id=\"78\"]\n<h2>Medical Specialties and Procedures Related to the Respiratory System<\/h2>\n<h3>Respiratory Therapists (RTs)<\/h3>\nRespiratory therapists (RTs) are healthcare professionals that monitor, assess, and treat people who are having problems breathing. RTs must have at least a two-year degree. RTs measure lung capacity, test oxygen and carbon dioxide levels, perform chest physiotherapy to remove mucus from patients' lungs, and operate ventilator equipment (Bureau of Labor Statistics, 2021). For more information, visit the <a href=\"https:\/\/www.aarc.org\/careers\/what-is-an-rt\/\">American Association for Respiratory Care web page<\/a>.\n<h3>Thoracic Surgeon<\/h3>\nA thoracic surgeon refers to a surgeon who has specialized in either thoracic (chest) surgery or cardiothoracic (heart and chest) surgery (National Cancer Institute, n.d.). To learn about the career path, read <a href=\"https:\/\/www.sts.org\/sites\/default\/files\/documents\/ResidentsFAQ_FINAL_06042018.pdf\">this PDF from The Society of Thoracic Surgeons.<\/a>\n<h3>Spirometry Testing<\/h3>\n<\/div>\n<section id=\"fs-id810328\" class=\"summary\"><\/section><section id=\"fs-id2345620\" class=\"interactive-exercise\">\n<div id=\"fs-id2522180\" class=\"exercise\">\n<div id=\"fs-id2801773\" class=\"problem\"><section id=\"fs-id810328\" class=\"summary\">\n<p id=\"fs-id2626519\">Spirometry testing is used to find out how well lungs are working by measuring air volume.<\/p>\n\n<ul>\n \t<li><strong>Respiratory volume<\/strong> describes the amount of air in a given space within the lungs, or which can be moved by the lung, and is dependent on a variety of factors.<\/li>\n \t<li><strong>Tidal volume <\/strong>refers to the amount of air that enters the lungs during quiet breathing, whereas inspiratory reserve volume is the amount of air that enters the lungs when a person inhales past the tidal volume.<\/li>\n \t<li><strong>Expiratory reserve volume<\/strong> is the extra amount of air that can leave with forceful expiration, following tidal expiration.<\/li>\n \t<li><strong>Residual volume<\/strong> is the amount of air that is left in the lungs after expelling the expiratory reserve volume.<\/li>\n \t<li><strong>Respiratory capacity <\/strong>is the combination of two or more volumes.<\/li>\n \t<li><strong> Anatomical dead space<\/strong> refers to the air within the respiratory structures that never participates in gas exchange, because it does not reach functional alveoli.<\/li>\n \t<li><strong> Respiratory rate <\/strong>is the number of breaths taken per minute, which may change during certain diseases or conditions.<\/li>\n<\/ul>\n<p id=\"fs-id2590391\">Both respiratory rate and depth are controlled by the respiratory centers of the brain, which are stimulated by factors such as chemical and pH changes in the blood. These changes are sensed by central chemoreceptors, which are located in the brain, and peripheral chemoreceptors, which are located in the aortic arch and carotid arteries. A rise in carbon dioxide or a decline in oxygen levels in the blood stimulates an increase in respiratory rate and depth.<\/p>\n\n<h4>Watch this video:<\/h4>\n<div class=\"textbox shaded\">\n\n[embed]http:\/\/youtube.com\/watch?v=M4C8EInOMOI[\/embed]\n\n<em>Media 12.3. <a href=\"http:\/\/youtube.com\/watch?v=M4C8EInOMOI\">Peak Flow and Spirometry - Lung Function Tests<\/a> [Online video]. Copyright 2012 by <a href=\"https:\/\/www.youtube.com\/channel\/UCh4bLGk7imxI7fWyk01c8fA\">Oxford Medical Education<\/a>.<\/em>\n\n<\/div>\n<h2>Respiratory System Vocabulary<\/h2>\n<\/section><\/div>\n<\/div>\n<\/section>\n<div id=\"fs-id1895080\" class=\"note anatomy interactive\">\n\n<strong>Adenoidectomy<\/strong>\n\nExcision of the adenoids.\n\n<strong>Alveolar duct<\/strong>\n\nSmall tube that leads from the terminal bronchiole to the respiratory bronchiole and is the point of attachment for alveoli.\n\n<strong>Alveolitis<\/strong>\n\nInflammation of the alveoli.\n\n<strong>Aphonia<\/strong>\n\nCondition of the absence of one's voice.\n\n<strong>Apnea<\/strong>\n\nA temporary absence of respiration.\n\n<strong>Asphyxia<\/strong>\n\nCondition caused by a lack of oxygen that leads to impending or actual death.\n\n<strong>Aspirate<\/strong>\n\nTo withdraw fluid, tissue, or other substances from a body cavity, cyst, or tumor.\n\n<strong>Atelectasis<\/strong>\n\nFailure of the lung to expand (inflate) completely.\n\n<strong>Autonomic<\/strong>\n\nInvoluntary or unconscious.\n\n<strong>Benign<\/strong>\n\nNon-cancerous.\n\n<strong>Bronchiectasis<\/strong>\n\nDilation of the bronchi.\n\n<strong>Bronchitis<\/strong>\n\nInflammation of the bronchus.\n\n<strong>Bronchodilators<\/strong>\n\nA type of drug that causes small airways in the lungs to open up.\n\n<strong>Bronchogenic carcinoma<\/strong>\n\nCancer that begins in the tissue that lines or covers the airways of the lungs, including small cell and non-small cell lung cancer.\n\n<strong>Bronchopneumonia<\/strong>\n\nInflammation of the lung, particularly the bronchioles and alveoli, that is associated with bronchitis.\n\n<strong>Bronchoscope<\/strong>\n\nA thin, tube-like instrument used to examine the inside of the trachea, bronchi, and lungs.\n\n<strong>Bronchoscopy<\/strong>\n\nA procedure involving a bronchoscope to examine the inside of the trachea, bronchi, and lungs.\n\n<strong>Bronchospasm<\/strong>\n\nSpasmodic contraction of the smooth muscle of the bronchi.\n\n<strong>Carcinogen<\/strong>\n\nAny substance that causes cancer.\n\n<strong>Cardiac notch<\/strong>\n\nAn indentation on the surface of the left lung.\n\n<strong>Carina<\/strong>\n\nA ridge at the base of the trachea (windpipe) that separates the openings of the right and left main bronchi (the large air passages that lead from the trachea to the lungs).\n\n<strong>Chronic<\/strong>\n\nA condition that lasts a long time with periods of remission and exacerbation.\n\n<strong>Computerized tomography (CT)<\/strong>\n\nA noninvasive imaging technique that uses computers to analyze several cross-sectional X-rays in order to reveal minute details about structures in the body.\n\n<strong>Conducting zone<\/strong>\n\nThe major functions of the conducting zone are to provide a route for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air.\n\n<strong>Cyanotic<\/strong>\n\nPertaining to abnormal color of blue (bluish color, lips and nail beds) caused by deoxygenation.\n\n<strong>Defensins<\/strong>\n\nThe lysozyme enzyme and proteins which have antibacterial properties.\n\n<strong>Diaphragm<\/strong>\n\nA sheet of skeletal muscle separating the thoracic and abdominal cavities that has to contract and relax for you to breathe.\n\n<strong>Dysphonia<\/strong>\n\nCondition of difficult speaking, including hoarseness and change in pitch or quality of the voice.\n\n<strong>Dyspnea<\/strong>\n\nDifficulty breathing.\n\n<strong>Epiglottitis<\/strong>\n\nInflammation of the epiglottis.\n\n<strong>Endoscope<\/strong>\n\nA thin, tube-like instrument used to look at tissues inside the body.\n\n<strong>Endoscopy<\/strong>\n\nA procedure that uses an endoscope to examine the inside of the body.\n\n<strong>Epiglottis<\/strong>\n\nLeaf-shaped piece of elastic cartilage that is a portion of the larynx that swings to close the trachea during swallowing.\n\n<strong>Epistaxis<\/strong>\n\nNosebleed.\n\n<strong>Erythrocytes<\/strong>\n\nRed blood cells.\n\n<strong>Eupnea<\/strong>\n\nA mode of breathing that occurs at rest and does not require the cognitive thought of the individual; also known as quiet breathing.\n\n<strong>Expiration<\/strong>\n\nExhalation, or the process of causing air to leave the lungs.\n\n<strong>External nose<\/strong>\n\nThe surface and skeletal structures that result in the outward appearance of the nose and contribute to its numerous functions.\n\n<strong>Fauces<\/strong>\n\nThe opening of the oral cavity into the pharynx.\n\n<strong>Fibroelastic membrane<\/strong>\n\nA flexible membrane that closes the posterior surface of the trachea, connecting the C-shaped cartilages.\n\n<strong>Glottis<\/strong>\n\nComposed of the vestibular folds, the true vocal cords, and the space between these folds.\n\n<strong>Hard palate<\/strong>\n\nLocated at the anterior region of the nasal cavity and is composed of bone.\n\n<strong>Hemothorax<\/strong>\n\nHemorrhage within the pleural cavity.\n\n<strong>Hematologist<\/strong>\n\nA doctor who has special training in diagnosing and treating blood disorders.\n\n<strong>Hematology<\/strong>\n\nThe study of blood and blood-forming issues.\n\n<strong>Hilum of the lung<\/strong>\n\nA concave region where blood vessels, lymphatic vessels, and nerves also enter the lungs.\n\n<strong>Hypercapnia<\/strong>\n\nAbnormally elevated blood levels of CO<sub>2 <\/sub>(carbon dioxide).\n\n<strong>Hyperpnea<\/strong>\n\nForced breathing or breathing that is excessive.\n\n<strong>Hypocapnia<\/strong>\n\nAbnormally low blood levels of CO<sub>2 <\/sub>(carbon dioxide).\n\n<strong>Hypoxemia<\/strong>\n\nBelow-normal level of oxygen saturation of blood (typically &lt;95 percent).\n\n<strong>Hypoxia<\/strong>\n\nLack of oxygen supply to the tissues.\n\n<strong>Inferior<\/strong>\n\nA position below or lower than another part of the body proper.\n\n<strong>Influenza (flu)<\/strong>\n\nAn acute viral infection involving the respiratory tract.\n\n<strong>Inspiration<\/strong>\n\nInhalation, or process of breathing air into the lungs.\n\n<strong>Laryngeal<\/strong>\n\nPertaining to the larynx.\n\n<strong>Laryngitis<\/strong>\n\nInflammation of the larynx.\n\n<strong>Laryngopharynx<\/strong>\n\nOne of the three regions of the pharynx; inferior to the oropharynx and posterior to the larynx.\n\n<strong>Laryngoplasty<\/strong>\n\nSurgical repair of the larynx.\n\n<strong>Laryngoscope<\/strong>\n\nA thin, tube-like instrument used to examine the larynx.\n\n<strong>Laryngoscopy<\/strong>\n\nExamination of the larynx with a mirror or laryngoscope.\n\n<strong>Larynx<\/strong>\n\nA cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs; also known as the voice box.\n\n<strong>Lobectomy<\/strong>\n\nExcision of the lobe(s) of an organ.\n\n<strong>Lymphocytes<\/strong>\n\nThe second most common type of leukocyte and are essential for the immune response.\n\n<strong>Malignant<\/strong>\n\nCancerous.\n\n<strong>Mucus<\/strong>\n\nA thick, slippery fluid made by the membranes that line certain organs of the body.\n\n<strong>Nasopharyngitis<\/strong>\n\nInflammation of the nose and pharynx.\n\n<strong>Nasopharynx<\/strong>\n\nThe upper part of the throat behind the nose. An opening on each side of the nasopharynx leads into the ear.\n\n<strong>Nebulizer<\/strong>\n\nA device used to turn liquid into a fine spray.\n\n<strong>Nosocomial infection<\/strong>\n\nInfection acquired in hospital.\n\n<strong>Oropharynx<\/strong>\n\nA passageway for both air and food; borders the nasopharynx and the oral cavity.\n\n<strong>Oximeter<\/strong>\n\nInstrument used to measure the oxygenation of tissues.\n\n<strong>Pharyngeal tonsil<\/strong>\n\nThe tonsil located at the back of the throat; also known as the adenoid when swollen.\n\n<strong>Pharyngitis<\/strong>\n\nInflammation of the pharynx.\n\n<strong>Pharynx<\/strong>\n\nA tube formed by skeletal muscle and lined by mucous membrane that is continuous with that of the nasal cavities; also known as the throat.\n\n<strong>Pleural effusion<\/strong>\n\nAn abnormal collection of fluid between the thin layers of tissue (pleura) lining the lung and the wall of the chest cavity.\n\n<strong>Pleurisy<\/strong>\n\nInflammation of the pleura.\n\n<strong>Pneumoconiosis<\/strong>\n\nA condition caused by the inhalation of dust.\n\n<strong>Pneumonectomy<\/strong>\n\nExcision of the lung.\n\n<strong>Pneumonia<\/strong>\n\nA severe inflammation of the lungs in which the alveoli (tiny air sacs) are filled with fluid.\n\n<strong>Pneumothorax<\/strong>\n\nAn abnormal collection of air in the space between the thin layer of tissue that covers the lungs and the chest cavity that can cause all or part of the lung to collapse.\n\n<strong>Polysomnography (PSG)<\/strong>\n\nSimultaneous and continuous monitoring of several parameters during sleep to study normal and abnormal sleep.\n\n<strong>Posterior<\/strong>\n\nDescribes the back or direction toward the back of the body.\n\n<strong>Pulmonary artery<\/strong>\n\nArtery that arises from the pulmonary trunk.\n\n<strong>Pulmonary edema<\/strong>\n\nFluid accumulation in alveoli and bronchioles (related to heart failure).\n\n<strong>Pulmonary embolism\u00a0<\/strong>\n\nA blood clot within the lung.\n\n<strong>Radiologist<\/strong>\n\nA doctor who has special training in creating and interpreting pictures of areas inside the body.\n\n<strong>Radiography<\/strong>\n\nA procedure that uses x-rays to take pictures of areas inside the body.\n\n<strong>Radiology<\/strong>\n\nThe use of radiation or other imaging technologies to diagnose or treat disease.\n\n<strong>Respiratory zone<\/strong>\n\nThe respiratory zone includes structures that are directly involved in gas exchange.\n\n<strong>Rhinitis<\/strong>\n\nInflammation of the mucous membranes of the nose.\n\n<strong>Rhinoplasty<\/strong>\n\nA plastic surgical operation on the nose, either reconstructive, restorative, or cosmetic.\n\n<strong>Rhinorrhea <\/strong>\n\nExcess nasal drainage; also called a \"runny nose.\"\n\n<strong>Septal cartilage <\/strong>\n\nThe flexible hyaline cartilage connected to the nasal bone.\n\n<strong>Sinusitis<\/strong>\n\nInflammation of the sinuses.\n\n<strong>Soft palate<\/strong>\n\nLocated at the posterior portion of the nasal cavity and consists of muscle tissue.\n\n<strong>Sonogram<\/strong>\n\nA computer picture of areas inside the body created by high-energy sound waves.\n\n<strong>Spirometry<\/strong>\n\nThe measurement of volume of air inhaled or exhaled by the lung.\n\n<strong>Sputum<\/strong>\n\nMucus and other matter brought up from the lungs by coughing.\n\n<strong>Stethoscope<\/strong>\n\nAn instrument is used to hear sounds produced by the heart, lungs, or other parts of the body.\n\n<strong>Sympathetic nervous system (SNS)<\/strong>\n\nThe division of the nervous system involved in our fight-or-flight responses. It continuously monitors body temperature and initiates appropriate motor responses.\n\n<strong>Tachypnea<\/strong>\n\nRapid breathing.\n\n<strong>Thoracalgia<\/strong>\n\nPain in the chest.\n\n<strong>Thoracentesis<\/strong>\n\nRemoval of fluid from the pleural cavity through a needle inserted between the ribs.\n\n<strong>Thoracic<\/strong>\n\nPertaining to the chest.\n\n<strong>Thoracoscope<\/strong>\n\nA thin tube-like instrument used to examine the inside of the chest.\n\n<strong>Thoracoscopy<\/strong>\n\nExamination of the inside of the chest, using a thoracoscope.\n\n<strong>Thoracotomy<\/strong>\n\nAn operation to open the chest.\n\n<strong>Tonsillectomy<\/strong>\n\nExcision of the tonsils.\n\n<strong>Tonsillitis<\/strong>\n\nInflammation of the tonsils.\n\n<strong>Tracheitis<\/strong>\n\nInflammation of the trachea.\n\n<strong>Tracheostomy<\/strong>\n\nSurgery to create an opening into the trachea.\n\n<strong>Tracheotomy<\/strong>\n\nSurgical incision of the trachea.\n\n<strong>Trachea<\/strong>\n\nThe windpipe.\n\n<strong>Upper respiratory infection<\/strong>\n\nInfection of the nasal cavity, pharynx and larynx cause by a virus.\n\n<strong>Uvula <\/strong>\n\nA small bulbous, teardrop-shaped structure located at the apex of the soft palate.\n\n<strong>Ventilator<\/strong>\n\nA machine used to help a patient breathe.\n\n<\/div>\n<h2><strong>Test Yourself<\/strong><\/h2>\n[h5p id=\"79\"]\n<h2>References<\/h2>\nBureau of Labor Statistics. (2021). Respiratory therapists. In <em>Occupational outlook handbook<\/em>. U.S. Department of Labor. <a href=\"https:\/\/www.bls.gov\/ooh\/healthcare\/respiratory-therapists.htm\">https:\/\/www.bls.gov\/ooh\/healthcare\/respiratory-therapists.htm<\/a>\n\nCrashCourse. (2015, August 24). <em>Respiratory system, part 1: crash course A&amp;P #31<\/em> [Video]. YouTube. <a href=\"https:\/\/youtu.be\/bHZsvBdUC2I\">https:\/\/youtu.be\/bHZsvBdUC2I<\/a>\n\nCrashCourse. (2015, August 31). <em>Respiratory system, part 2: crash course A&amp;P #32<\/em> [Video]. YouTube. <a href=\"https:\/\/youtu.be\/Cqt4LjHnMEA\">https:\/\/youtu.be\/Cqt4LjHnMEA<\/a>\n\nNational Cancer Institute. (n.d.). <em>Thoracic surgeon definition<\/em>. National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.cancer.gov\/publications\/dictionaries\/cancer-terms\/def\/thoracic-surgeon\">https:\/\/www.cancer.gov\/publications\/dictionaries\/cancer-terms\/def\/thoracic-surgeon<\/a>\n\nNational Cancer Institute. (2021a). <em>Non-small cell lung cancer treatment (PDQ\u00ae)-Patient version<\/em>. National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.cancer.gov\/types\/lung\/patient\/non-small-cell-lung-treatment-pdq\">https:\/\/www.cancer.gov\/types\/lung\/patient\/non-small-cell-lung-treatment-pdq<\/a>\n\nNational Cancer Institute. (2021b). <em>Small cell cancer treatment (PDQ\u00ae)-Patient version<\/em>. National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.cancer.gov\/types\/lung\/patient\/small-cell-lung-treatment-pdq\">https:\/\/www.cancer.gov\/types\/lung\/patient\/small-cell-lung-treatment-pdq<\/a>\n\nNational Heart, Lung, and Blood Institute. (n.d.). <em>COPD.<\/em> National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.nhlbi.nih.gov\/health-topics\/copd\">https:\/\/www.nhlbi.nih.gov\/health-topics\/copd<\/a>\n\nOxford Medical Education. (2012, May 13). <em>Peak flow and spirometry - Lung function tests<\/em> [Video]. YouTube. <a href=\"https:\/\/www.youtube.com\/watch?v=M4C8EInOMOI\">https:\/\/www.youtube.com\/watch?v=M4C8EInOMOI<\/a>\n<h2>Image Descriptions<\/h2>\n<a id=\"Figure12.1id\" href=\"\"><\/a><strong>Figure 12.1 image description:<\/strong> This figure shows the upper half of the human body. The major organs in the respiratory system are labeled. <a href=\"#Figure12.1\">[Return to Figure 12.1].<\/a>\n\n<a id=\"Figure12.2id\" href=\"\"><\/a><strong>Figure 12.2 image description:<\/strong> This figure shows a cross section view of the nose and throat. The major parts are labeled. <a href=\"#Figure12.2\">[Return to Figure 12.2].<\/a>\n\n<a id=\"Figure12.3id\" href=\"\"><\/a><strong>Figure 12.3 image description:<\/strong> This figure shows a micrograph of pseudostratified epithelium. <a href=\"#Figure12.3\">[Return to Figure 12.3].<\/a>\n\n<a id=\"Figure12.4id\" href=\"\"><\/a><strong>Figure 12.4 image description:<\/strong> This figure shows the side view of the face. The different parts of the pharynx are color-coded and labeled (from the top): nasal cavity, hard palate, soft palate, tongue, epiglottis, larynx, esophagus, trachea. <a href=\"#Figure12.4\">[Return to Figure 12.4].<\/a>\n\n<a id=\"Figure12.5id\" href=\"\"><\/a><strong>Figure 12.5 image description:<\/strong> The top panel of this figure shows the anterior view of the larynx, and the bottom panel shows the right lateral view of the larynx. <a href=\"#Figure12.5\">[Return to Figure 12.5].<\/a>\n\n<a id=\"Figure12.6id\" href=\"\"><\/a><strong>Figure 12.6 image description:<\/strong> This diagram shows the cross-section of the larynx. The different types of cartilages are labeled (clockwise from top): pyriform fossa, true vocal cord, epiglottis, tongue, glottis, vestibular fold, trachea, esophagus. <a href=\"#Figure12.6\">[Return to Figure 12.6].<\/a>\n\n<a id=\"Figure12.7id\" href=\"\"><\/a><strong>Figure 12.7 image description:<\/strong> The top panel of this figure shows the trachea and its organs. The major parts including the larynx, trachea, bronchi, and lungs are labeled. <a href=\"#Figure12.7\">[Return to Figure 12.7].<\/a>\n\n<a id=\"Figure12.8id\" href=\"\"><\/a><strong>Figure 12.8 image description:<\/strong> This image shows the bronchioles and alveolar sacs in the lungs and depicts the exchange of oxygenated and deoxygenated blood in the pulmonary blood vessels. <a href=\"#Figure12.8\">[Return to Figure 12.8].<\/a>\n\n<a id=\"Figure12.9id\" href=\"\"><\/a><strong>Figure 12.9 image description:<\/strong> This figure shows the detailed structure of the alveolus. The top panel shows the alveolar sacs and the bronchioles. The middle panel shows a magnified view of the alveolus, and the bottom panel shows a micrograph of the cross section of a bronchiole. <a href=\"#Figure12.9\">[Return to Figure 12.9].<\/a>\n\n<a id=\"Figure12.10id\" href=\"\"><\/a><strong>Figure 12.10 image description:<\/strong> Diagram of the lungs with the major parts labelled (from top, clockwise): trachea, superior lobe, main bronchus, lobar bronchus, segmental bronchus, inferior lobe, inferior lobe, middle lobe, superior lobe of the left lung. <a href=\"#Figure12.10\">[Return to Figure 12.10].<\/a>\n\n<a id=\"Figure12.11id\" href=\"\"><\/a><strong>Figure 12.11 image description:<\/strong> This figure shows the lungs and the chest wall, which protects the lungs, in the left panel. In the right panel, a magnified image shows the pleural cavity and a pleural sac. <a href=\"#Figure12.11\">[Return to Figure 12.11].<\/a>\n\n<a id=\"Figure12.12id\" href=\"\"><\/a><strong>Figure 12.12 image description:<\/strong> The left panel of this image shows a person inhaling air and the location of the chest muscles. The right panel shows the person exhaling air and the contraction of the thoracic cavity. <a href=\"#Figure12.12\">[Return to Figure 12.12].<\/a>\n\n&nbsp;\n\n<section id=\"fs-id2517312\" class=\"summary\">\n<div class=\"textbox shaded\">Unless otherwise indicated, this chapter contains material adapted from <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction\"><em>Anatomy and Physiology<\/em><\/a> (on <a href=\"https:\/\/openstax.org\/\">OpenStax<\/a>), by Betts et al. and is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0 international license<\/a>. Download and access this book for free at <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction\">https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction<\/a>.<\/div>\n&nbsp;\n\n<\/section>","rendered":"<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\"><em>Learning Objectives<\/em><\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"textbox__content\">\n<ul>\n<li>Examine the anatomy of the respiratory system<\/li>\n<li>Determine the main functions of the respiratory system<\/li>\n<li>Differentiate respiratory system medical terms and common abbreviations<\/li>\n<li>Recognize the medical specialties associated with the respiratory system<\/li>\n<li>Discover common diseases, disorders, and procedures related to the respiratory system<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<h2>Respiratory System Word Parts<\/h2>\n<p>Click on prefixes, combining forms, and suffixes to reveal a list of word parts to memorize for the Respiratory System.<\/p>\n<p>&nbsp;<\/p>\n<div id=\"h5p-71\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-71\" class=\"h5p-iframe\" data-content-id=\"71\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: Word Parts\"><\/iframe><\/div>\n<\/div>\n<h2>Introduction to the Respiratory System<\/h2>\n<div class=\"textbox__content\">\n<p>How long you can hold your breath as you continue reading\u2026 How long can you do it? Chances are you are feeling uncomfortable already. A typical human cannot survive without breathing for more than three minutes, and even if you wanted to hold your breath longer, your <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_259\">autonomic<\/a> nervous system would take control. <span style=\"text-align: initial;font-size: 1em\">Although oxygen is critical for cells, it is the accumulation of carbon dioxide that primarily drives your need to breathe.<\/span><\/p>\n<\/div>\n<p>The major structures of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acid-base balance. Portions of the respiratory system are also used for non-vital functions, such as sensing odors, speech production, and for straining, such as coughing.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 420px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2020\/05\/2301_Major_Respiratory_Organs.jpg\" alt=\"Major respiratory structures. Image description available.\" width=\"420\" height=\"1625\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.1\" href=\"\"><\/a>Figure 12.1 Major Respiratory Structures. The major respiratory structures span the nasal cavity to the diaphragm. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.1id\">[Image description.]<\/a><\/figcaption><\/figure>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p><span class=\"tight\">If you hold your breath for longer than 3 minutes, your autonomic nervous system will take control.<\/span><\/p>\n<\/div>\n<\/div>\n<h3>Watch this video:<\/h3>\n<div class=\"textbox shaded\">\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Respiratory System, Part 1: Crash Course Anatomy &amp; Physiology #31\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/bHZsvBdUC2I?feature=oembed&#38;rel=0&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><em>Media 12.1. <a href=\"https:\/\/youtu.be\/bHZsvBdUC2I\">Respiratory System, Part 1: Crash Course A&amp;P #31<\/a> [Online video]. Copyright 2015 by <a href=\"https:\/\/www.youtube.com\/user\/crashcourse\/about\">CrashCourse<\/a>.<\/em><\/p>\n<\/div>\n<h2>Practice Medical Terms Related to the Respiratory System<\/h2>\n<p><span style=\"float: none;background-color: transparent;color: #333333;cursor: text;font-family: 'Lora',serif;font-size: 16px;font-style: normal;font-variant: normal;font-weight: 400;letter-spacing: normal;text-align: left;text-decoration: none;text-indent: 0px;text-transform: none\"><\/p>\n<div id=\"h5p-72\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-72\" class=\"h5p-iframe\" data-content-id=\"72\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: Medical Terms\"><\/iframe><\/div>\n<\/div>\n<p><\/span><\/p>\n<h2>Anatomy (Structures) of the Respiratory System<\/h2>\n<figure id=\"fig-ch23_01_01\"><\/figure>\n<h3 id=\"fs-id2061706\">The Nose and its Adjacent Structures<\/h3>\n<section id=\"fs-id1938446\">\n<section id=\"fs-id2486828\">\n<p id=\"fs-id2271107\">The major entrance and exit for the respiratory system is through the <strong>nose<\/strong>. When discussing the nose, it is helpful to divide it into two major sections:<\/p>\n<ul>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_301\">external nose<\/a><\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_546\">internal nose<\/a><\/li>\n<\/ul>\n<p>The <strong>nares<\/strong> open into the nasal cavity, which is separated into left and right sections by the nasal septum (<a class=\"autogenerated-content\" href=\"#fig-ch23_01_03\">Figure 12.2<\/a>). The <strong>nasal septum<\/strong> is formed anteriorly by a portion of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_302\">septal cartilage<\/a> and posteriorly by the perpendicular plate of the ethmoid bone and the thin vomer bones.<\/p>\n<p><span style=\"font-size: 1em\">Each lateral wall of the nasal cavity has three bony projections: <\/span><span style=\"font-size: 1em\">t<\/span><span style=\"font-size: 1em\">he inferior conchae are separate bones, and t<\/span><span style=\"font-size: 1em\">he superior and middle conchae are portions of the ethmoid bone. <\/span><span style=\"font-size: 1em\"><strong>Conchae<\/strong> increase the surface area of the nasal cavity, disrupting the flow of air as it enters the nose and causing air to bounce along the epithelium, where it is cleaned and warmed. <\/span><span style=\"font-size: 1em\">The conchae and meatuses trap water during exhalation preventing dehydration.<\/span><\/p>\n<p><span style=\"font-size: 1em\">The floor of the nasal cavity is composed of the<\/span><span style=\"font-size: 1em\"> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_303\">hard palate<\/a> and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_304\">soft palate<\/a>. <\/span><span style=\"font-size: 1em\">Air exits the nasal cavities via the internal nares and moves into the pharynx.<\/span><\/p>\n<figure id=\"fig-ch23_01_03\">\n<figure style=\"width: 450px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2303_Anatomy_of_Nose-Pharynx-Mouth-Larynx.jpg\" alt=\"Diagram of the upper airway. Image description available.\" width=\"450\" height=\"1600\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.2\" href=\"\"><\/a>Figure 12.2 Upper Airway. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.2id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<p><strong>Paranasal sinuses<\/strong> serve to warm and humidify incoming air and are lined with a mucosa which produces mucus. Paranasal sinuses are named for their associated bone:<\/p>\n<ul>\n<li>frontal sinus<\/li>\n<li>maxillary sinus<\/li>\n<li>sphenoidal sinus<\/li>\n<li>ethmoidal sinus<\/li>\n<\/ul>\n<p>The nares and anterior portion of the nasal cavities are lined with mucous membranes, containing sebaceous glands and hair follicles that serve to prevent the passage of large debris, such as dirt, through the nasal cavity. An olfactory epithelium used to detect odors is found deeper in the nasal cavity.<\/p>\n<p>The conchae, meatuses, and paranasal sinuses are lined by respiratory epithelium composed of pseudostratified ciliated columnar epithelium (<a class=\"autogenerated-content\" href=\"#fig-ch23_01_04\">Figure 12.3<\/a>). The epithelium contains specialized epithelial cells that produce mucus to trap debris. <span style=\"font-size: 1em\">The cilia of the respiratory epithelium help to remove mucus and debris with a constant beating motion, sweeping materials towards the throat to be swallowed. <\/span><\/p>\n<p><span style=\"font-size: 1em;text-align: initial\">This moist epithelium functions to warm and humidify incoming air. <\/span><span style=\"font-size: 1em;text-align: initial\">Capillaries located just beneath the nasal epithelium warm the air by convection. Serous and mucus-producing cells also secrete <strong>defensins<\/strong>, or immune cells that patrol the connective tissue providing additional protection.<\/span><\/p>\n<figure id=\"fig-ch23_01_04\"><figcaption><\/figcaption><figure style=\"width: 500px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2304_Pseudostratified_Epithelium.jpg\" alt=\"Pseudostratified Ciliated Columnar Epithelium. Image description available.\" width=\"500\" height=\"1131\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.3\" href=\"\"><\/a>Figure 12.3 Pseudostratified Ciliated Columnar Epithelium. Respiratory epithelium is pseudostratified ciliated columnar epithelium. Seromucous glands provide lubricating mucus. LM \u00d7 680. (Micrograph provided by the Regents of University of Michigan Medical School \u00a9 2012). From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.3id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<div id=\"fs-id2103496\" class=\"note anatomy interactive um\">\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p><span class=\"tight\">Cold air slows the movement of cilia that may result in the accumulation of mucus, leading to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_293\">rhinorrhea<\/a> during cold weather.<\/span><\/p>\n<\/div>\n<\/div>\n<h3 id=\"fs-id1983622\">Pharynx<\/h3>\n<\/div>\n<\/section>\n<section id=\"fs-id2419331\">\n<p id=\"fs-id2020239\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_307\">pharynx<\/a> is divided into three major regions: the <strong>nasopharynx<\/strong>, the <strong>oropharynx<\/strong>, and the <strong>laryngopharynx<\/strong> (see <a class=\"autogenerated-content\" href=\"#fig-ch23_01_05\">Figure 12.4<\/a>).<\/p>\n<figure id=\"fig-ch23_01_05\"><figcaption><\/figcaption><figure style=\"width: 475px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2305_Divisions_of_the_Pharynx.jpg\" alt=\"Divisions of the pharynx. Image description available.\" width=\"475\" height=\"1496\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.4\" href=\"\"><\/a>Figure 12.4 Divisions of the Pharynx. The pharynx is divided into three regions: the nasopharynx, the oropharynx, and the laryngopharynx. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.4id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<p id=\"fs-id2591817\">At the top of the <strong>nasopharynx<\/strong> are the pharyngeal tonsils. The function of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_317\">pharyngeal<\/a> tonsil is not well understood, but it contains a rich supply of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_705\">lymphocytes<\/a> and is covered with ciliated epithelium that traps and destroys invading pathogens that enter during inhalation. The pharyngeal tonsils are large in children but tend to regress with age and may even disappear. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_310\">uvula<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_304\">soft palate<\/a> move like a pendulum during swallowing, swinging upward to close off the nasopharynx to prevent ingested materials from entering the nasal cavity. Auditory (Eustachian) tubes that connect to each middle ear cavity open into the nasopharynx. This connection is why colds often lead to ear infections.<\/p>\n<p id=\"fs-id2641568\">The <strong>oropharynx<\/strong> is bordered superiorly by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_308\">nasopharynx<\/a> and anteriorly by the oral cavity. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_311\">oropharynx<\/a> contains two distinct sets of tonsils:<\/p>\n<ul>\n<li>The palatine tonsils.\n<ul>\n<li>A palatine tonsil is one of a pair of structures located laterally in the oropharynx in the area of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_312\">fauces<\/a>.<\/li>\n<\/ul>\n<\/li>\n<li>The lingual tonsils.\n<ul>\n<li>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_318\">lingual<\/a> tonsil is located at the base of the tongue.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>Similar to the pharyngeal tonsil, the palatine and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_318\">lingual<\/a> tonsils are composed of lymphoid tissue, and trap and destroy pathogens entering the body through the oral or nasal cavities.<\/p>\n<p id=\"fs-id1639121\">The <strong>laryngopharynx<\/strong> is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_321\">inferior<\/a> to the oropharynx and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_322\">posterior<\/a> to the larynx. It continues the route for ingested material and air until its <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_321\">inferior<\/a> end, where the digestive and respiratory systems diverge. The stratified squamous epithelium of the oropharynx is continuous with the laryngopharynx. Anteriorly, the laryngopharynx opens into the larynx, whereas <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_398\">posteriorly<\/a>, it enters the esophagus.<\/p>\n<\/section>\n<section>\n<h3>Larynx<\/h3>\n<p id=\"fs-id2874398\">The structure of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_313\">larynx<\/a> is formed by several pieces of cartilage. Three large cartilage pieces form the major structure of the larynx.<\/p>\n<ul>\n<li>Thyroid cartilage (anterior):\n<ul>\n<li>The thyroid cartilage is the largest piece of cartilage that makes up the larynx. The thyroid cartilage consists of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_314\">laryngeal<\/a> prominence, or \u201cAdam\u2019s apple,\u201d which tends to be more prominent in males.<\/li>\n<\/ul>\n<\/li>\n<li>Epiglottis (superior):\n<ul>\n<li>Three smaller, paired cartilages\u2014the arytenoids, corniculates, and cuneiforms\u2014attach to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_315\">epiglottis<\/a> and the vocal cords and muscle that help move the vocal cords to produce speech.<\/li>\n<\/ul>\n<\/li>\n<li>Cricoid cartilage (inferior):\n<ul>\n<li>The thick cricoid cartilage forms a ring, with a wide posterior region and a thinner anterior region.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<figure id=\"fig-ch23_01_06\"><figcaption><\/figcaption><figure style=\"width: 450px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2306_The_Larynx.jpg\" alt=\"Anterior and right lateral view of the larynx. Image description available.\" width=\"450\" height=\"1673\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.5\" href=\"\"><\/a>Figure 12.5 Larynx. The larynx extends from the laryngopharynx and the hyoid bone to the trachea. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.5id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<p id=\"fs-id2637383\">When the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_315\">epiglottis<\/a> is in the \u201cclosed\u201d position, the unattached end of the epiglottis rests on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_316\">glottis<\/a>. A vestibular fold, or false vocal cord, is one of a pair of folded sections of mucous membrane. A true vocal cord is one of the white, membranous folds attached by muscle to the thyroid and arytenoid cartilages of the larynx on their outer edges. The inner edges of the true vocal cords are free, allowing oscillation to produce sound.<\/p>\n<p>The act of swallowing causes the pharynx and larynx to lift upward, allowing the pharynx to expand and the epiglottis of the larynx to swing downward, closing the opening to the trachea. These movements produce a larger area for food to pass through, while preventing food and beverages from entering the trachea.<\/p>\n<figure id=\"fig-ch23_01_07\"><figcaption><\/figcaption><figure style=\"width: 450px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2307_Cartilages_of_the_Larynx.jpg\" alt=\"Cross-section of the vocal cords. Image description available.\" width=\"450\" height=\"1133\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.6\" href=\"\"><\/a>Figure 12.6 Vocal Cords. The true vocal cords and vestibular folds of the larynx are viewed inferiorly from the laryngopharynx. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.6id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<p id=\"fs-id2338748\">Similar to the nasal cavity and nasopharynx, this specialized epithelium produces mucus to trap debris and pathogens as they enter the trachea. The cilia beat the mucus upward towards the laryngopharynx, where it can be swallowed down the esophagus.<\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p><span class=\"tight\" style=\"direction: ltr\">Folds of the true vocal cords differ between individuals resulting in voices with different pitches.<\/span><\/p>\n<\/div>\n<\/div>\n<\/section>\n<section id=\"fs-id2718252\">\n<h3>Trachea<\/h3>\n<p id=\"fs-id2058199\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_319\">trachea<\/a> is formed by 16 to 20 stacked, C-shaped pieces of hyaline cartilage that are connected by dense connective tissue. The trachealis muscle and elastic connective tissue together form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_320\">fibroelastic membrane<\/a>. The fibroelastic membrane allows the trachea to stretch and expand slightly during inhalation and exhalation, whereas the rings of cartilage provide structural support and prevent the trachea from collapsing. The trachealis muscle can be contracted to force air through the trachea during exhalation. The trachea is lined with pseudostratified ciliated columnar epithelium, which is continuous with the larynx. The esophagus borders the trachea posteriorly.<\/p>\n<figure id=\"fig-ch23_01_08\"><figcaption><\/figcaption><figure style=\"width: 560px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2308_The_Trachea.jpg\" alt=\"Trachea and lungs. Image description available.\" width=\"560\" height=\"1430\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.7\" href=\"\"><\/a>Figure 12.7 Trachea. (a) The tracheal tube is formed by stacked, C-shaped pieces of hyaline cartilage. (b) The layer visible in this cross-section of tracheal wall tissue between the hyaline cartilage and the lumen of the trachea is the mucosa, which is composed of pseudostratified ciliated columnar epithelium that contains goblet cells. LM \u00d7 1220. (Micrograph provided by the Regents of University of Michigan Medical School \u00a9 2012). From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.7id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<\/section>\n<section id=\"fs-id2654941\">\n<h3>Bronchial Tree<\/h3>\n<p id=\"fs-id2033350\">The trachea branches into the right and left primary bronchi at the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_341\">carina<\/a>. These bronchi are also lined by pseudostratified ciliated columnar epithelium containing mucus-producing goblet cells (<a class=\"autogenerated-content\" href=\"#fig-ch23_01_08\">Figure 12.7b<\/a>). The carina is a raised structure that contains specialized nervous tissue that induces violent coughing if a foreign body, such as food, is present. Rings of cartilage, similar to those of the trachea, support the structure of the bronchi and prevent their collapse. The primary bronchi enter the lungs at the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_323\">hilum<\/a>. The bronchi continue to branch into a bronchial tree. A bronchial tree (or respiratory tree) is the collective term used for these multiple-branched bronchi. The main function of the bronchi, like other conducting zone structures, is to provide a passageway for air to move into and out of each lung. The mucous membrane traps debris and pathogens.<\/p>\n<p id=\"fs-id2138728\">A bronchiole branches from the tertiary bronchi. Bronchioles, which are about 1 mm in diameter, further branch until they become the tiny terminal bronchioles, which lead to the structures of gas exchange. There are more than 1,000 terminal bronchioles in each lung. The muscular walls of the bronchioles do not contain cartilage like those of the bronchi. This muscular wall can change the size of the tubing to increase or decrease airflow through the tube.<\/p>\n<\/section>\n<\/section>\n<section id=\"fs-id2875750\">\n<h3>Respiratory Zone<\/h3>\n<p id=\"fs-id2757673\">In contrast to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_300\">conducting zone<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_306\">respiratory zone<\/a> includes structures that are directly involved in gas exchange. The respiratory zone begins where the terminal bronchioles join a respiratory bronchiole, the smallest type of bronchiole (see <a class=\"autogenerated-content\" href=\"#fig-ch23_01_09\">Figure 12.8<\/a>), which then leads to an alveolar duct, opening into a cluster of alveoli.<\/p>\n<figure id=\"fig-ch23_01_09\"><figcaption><\/figcaption><figure style=\"width: 525px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2309_The_Respiratory_Zone.jpg\" alt=\"The respiratory zone. Image description available.\" width=\"525\" height=\"1671\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.8\" href=\"\"><\/a>Figure 12.8 Respiratory Zone. Bronchioles lead to alveolar sacs in the respiratory zone, where gas exchange occurs. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.8id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<section id=\"fs-id2918858\">\n<h3>Alveoli<\/h3>\n<p id=\"fs-id1980157\">An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_324\">alveolar duct<\/a> opens into a cluster of alveoli. An alveolus is one of the many small, grape-like sacs that are attached to the alveolar ducts. An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange. An alveolus is approximately 200 \u03bcm in diameter with elastic walls that allow the alveolus to stretch during air intake, which greatly increases the surface area available for gas exchange. Alveoli are connected to their neighbors by alveolar pores, which help maintain equal air pressure throughout the alveoli and lung (see <a class=\"autogenerated-content\" href=\"#fig-ch23_01_10\">Figure 12.9<\/a>).<\/p>\n<figure id=\"fig-ch23_01_10\"><figcaption><\/figcaption><figure style=\"width: 560px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2310_Structures_of_the_Respiratory_Zone.jpg\" alt=\"Structures of the respiratory zone. Image description available.\" width=\"560\" height=\"1155\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.9\" href=\"\"><\/a>Figure 12.9 Structures of the Respiratory Zone. (a) The alveolus is responsible for gas exchange. (b) A micrograph shows the alveolar structures within lung tissue. LM \u00d7 178. (Micrograph provided by the Regents of University of Michigan Medical School \u00a9 2012). From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.9id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<div id=\"fs-id1895080\" class=\"note anatomy interactive\">\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Concept Check<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>What are the components of the <strong>bronchial<\/strong> tree?<\/li>\n<li>What is the purpose of<strong> cilia<\/strong>?<\/li>\n<li>Where does<strong> gas<\/strong> exchange take place?<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h3 id=\"fs-id2817577\">Gross Anatomy of the Lungs<\/h3>\n<\/div>\n<\/section>\n<\/section>\n<section id=\"fs-id2517312\" class=\"summary\">\n<section id=\"fs-id2644915\">\n<p id=\"fs-id2627237\">The lungs are pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi; on the inferior surface, the lungs are bordered by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_547\">diaphragm<\/a>. The lungs are enclosed by the pleurae, which are attached to the mediastinum. The right lung is shorter and wider than the left lung, and the left lung occupies a smaller volume than the right. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_339\">cardiac notch<\/a> allows space for the heart (see <a class=\"autogenerated-content\" href=\"#fig-ch23_02_01\">Figure 12.10<\/a>). The apex of the lung is the superior region, whereas the base is the opposite region near the diaphragm. The costal surface of the lung borders the ribs. The mediastinal surface faces the midline.<\/p>\n<figure id=\"fig-ch23_02_01\">\n<figure style=\"width: 430px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2312_Gross_Anatomy_of_the_Lungs.jpg\" alt=\"Gross anatomy of the lungs. Image description available.\" width=\"430\" height=\"1304\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.10\" href=\"\"><\/a>Figure 12.10 Gross Anatomy of the Lungs. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.10id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<p id=\"fs-id2717313\">Each lung is composed of smaller units called lobes. Fissures separate these lobes from each other. The right lung consists of three lobes: the superior, middle, and inferior lobes. The left lung consists of two lobes: the superior and inferior lobes. A pulmonary lobule is a subdivision formed as the bronchi branch into bronchioles. Each lobule receives its own large bronchiole that has multiple branches. An interlobular septum is a wall, composed of connective tissue, which separates lobules from one another.<\/p>\n<\/section>\n<section><\/section>\n<h3>Can you correctly label the respiratory system structures?<\/h3>\n<section>\n<div id=\"h5p-73\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-73\" class=\"h5p-iframe\" data-content-id=\"73\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: Anatomy Activity\"><\/iframe><\/div>\n<\/div>\n<\/section>\n<h2>Physiology (Function) of the Respiratory System<\/h2>\n<section>\n<section id=\"fs-id2795878\">\n<h3>Blood Supply<\/h3>\n<p id=\"fs-id2144132\">The major function of the lungs is to perform gas exchange, which requires blood from the pulmonary circulation.<\/p>\n<ul>\n<li style=\"text-align: left\">This blood supply contains deoxygenated blood and travels to the lungs where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_421\">erythrocytes<\/a> pick up oxygen to be transported to tissues throughout the body.<\/li>\n<li style=\"text-align: left\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_340\">pulmonary artery<\/a> carries deoxygenated, arterial blood to the alveoli.<\/li>\n<li style=\"text-align: left\">The pulmonary artery branches multiple times as it follows the bronchi, and each branch becomes progressively smaller in diameter.<\/li>\n<li style=\"text-align: left\">One arteriole and an accompanying venule supply and drain one pulmonary lobule. As they near the alveoli, the pulmonary arteries become the pulmonary capillary network.<\/li>\n<li style=\"text-align: left\">The pulmonary capillary network consists of tiny vessels with very thin walls that lack smooth muscle fibers.<\/li>\n<li style=\"text-align: left\">The capillaries branch and follow the bronchioles and structure of the alveoli. It is at this point that the capillary wall meets the alveolar wall, creating the respiratory membrane.<\/li>\n<li style=\"text-align: left\">Once the blood is oxygenated, it drains from the alveoli by way of multiple pulmonary veins, which exit the lungs through the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_323\">hilum<\/a>.<\/li>\n<\/ul>\n<\/section>\n<h3>Nervous Innervation<\/h3>\n<p id=\"fs-id2179965\">The blood supply of the lungs plays an important role in gas exchange and serves as a transport system for gases throughout the body. Innervation by both the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_548\">parasympathetic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_337\">sympathetic nervous systems<\/a> provides an important level of control through dilation and constriction of the airway.<\/p>\n<ul>\n<li>The parasympathetic system causes bronchoconstriction.<\/li>\n<li>The sympathetic nervous system stimulates bronchodilation.<\/li>\n<\/ul>\n<p>Reflexes such as coughing, and the ability of the lungs to regulate oxygen and carbon dioxide levels, also result from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_259\">autonomic<\/a> nervous system control. Sensory nerve fibers arise from the vagus nerve, and from the second to fifth thoracic ganglia. The pulmonary plexus is a region on the lung root formed by the entrance of the nerves at the hilum. The nerves then follow the bronchi in the lungs and branch to innervate muscle fibers, glands, and blood vessel<span style=\"font-size: 1em\">s.<\/span><\/p>\n<\/section>\n<section id=\"fs-id2293350\">\n<h3>Pleura of the Lungs<\/h3>\n<p>Each lung is enclosed within a cavity that is surrounded by the pleura. The pleura (plural = pleurae) is a serous membrane that surrounds the lung. The right and left pleurae, which enclose the right and left lungs, respectively, are separated by the mediastinum.<\/p>\n<p>The pleurae consist of two layers:<\/p>\n<ol>\n<li>The <strong>visceral pleura<\/strong> is the layer that is superficial to the lungs and extends into and lines the lung fissures (see <a class=\"autogenerated-content\" href=\"#fig-ch23_02_02\">Figure 12.11<\/a>).<\/li>\n<li>The <strong>parietal pleura<\/strong> is the outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm.<\/li>\n<\/ol>\n<p>The visceral and parietal pleurae connect to each other at the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_323\">hilum<\/a>. The pleural cavity is the space between the visceral and parietal layers.<\/p>\n<figure id=\"fig-ch23_02_02\">\n<figure style=\"width: 440px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2313_The_Lung_Pleurea.jpg\" alt=\"Parietal and visceral pleurae of the lungs. Image description available.\" width=\"440\" height=\"1450\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.11\" href=\"\"><\/a>Figure 12.11 Parietal and Visceral Pleurae of the Lungs. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.11id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<p id=\"fs-id2078585\">The pleurae perform two major functions:<\/p>\n<ol>\n<li><strong>Produce pleural fluid<\/strong> that lubricates surfaces, reduces friction to prevent trauma during breathing, and creates surface tension that helps maintain the position of the lungs against the thoracic wall. This adhesive characteristic of the pleural fluid causes the lungs to enlarge when the thoracic wall expands during ventilation, allowing the lungs to fill with air.<\/li>\n<li>The pleurae also <strong>create a division<\/strong> between major organs that prevents interference due to the movement of the organs, while preventing the spread of infection.<\/li>\n<\/ol>\n<div id=\"fs-id2239873\" class=\"note anatomy everyday\">\n<h3>Pulmonary Ventilation<\/h3>\n<\/div>\n<\/section>\n<section id=\"fs-id2773018\" class=\"summary\">\n<p id=\"fs-id2241368\">The difference in pressures drives pulmonary ventilation because air flows down a pressure gradient, that is, air flows from an area of higher pressure to an area of lower pressure.<\/p>\n<ul>\n<li>Air flows into the lungs largely due to a difference in pressure; atmospheric pressure is greater than intra-alveolar pressure, and intra-alveolar pressure is greater than intrapleural pressure.<\/li>\n<li>Air flows out of the lungs during expiration based on the same principle; pressure within the lungs becomes greater than the atmospheric pressure.<\/li>\n<\/ul>\n<p id=\"fs-id1882180\">Pulmonary ventilation comprises two major steps: inspiration and expiration. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_342\">Inspiration<\/a> is the process of having air enter the lungs and expiration is the process of expelling air from the lungs (<a class=\"autogenerated-content\" href=\"#fig-ch23_03_03\">Figure 12.12<\/a>). <span style=\"font-size: 1em\">A respiratory cycle is one sequence of inspiration and expiration.<\/span><\/p>\n<p>Two muscle groups are used during <strong>normal inspiration<\/strong>: t<span style=\"font-size: 1em\">he diaphragm and the external intercostal muscles. Additional muscles can be used if a bigger breath is required. <\/span><\/p>\n<ul>\n<li><span style=\"font-size: 1em\">The diaphragm contracts, it moves inferiorly toward the abdominal cavity, creating a larger thoracic cavity and more space for the lungs.<\/span><\/li>\n<li>The external intercostal muscles contract and move the ribs upward and outward, causing the rib cage to expand, which increases the volume of the thoracic cavity.<\/li>\n<\/ul>\n<p>Due to the adhesive force of the pleural fluid, the expansion of the thoracic cavity forces the lungs to stretch and expand as well. This increase in volume leads to a decrease in intra-alveolar pressure, creating a pressure lower than atmospheric pressure. As a result, a pressure gradient is created that drives air into the lungs.<\/p>\n<figure id=\"fig-ch23_03_03\">\n<figure style=\"width: 450px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.ccconline.org\/accphysicalgeology\/wp-content\/uploads\/sites\/228\/2025\/03\/2316_Inspiration_and_Expiration.jpg\" alt=\"Inspiration and expiration process diagram. Image description available.\" width=\"450\" height=\"1422\" \/><figcaption class=\"wp-caption-text\"><a id=\"Figure12.12\" href=\"\"><\/a>Figure 12.12 Inspiration and Expiration. Inspiration and expiration occur due to the expansion and contraction of the thoracic cavity, respectively. From Betts et al., 2013. Licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0<\/a>. <a href=\"#Figure12.12id\">[Image description.]<\/a><\/figcaption><\/figure>\n<\/figure>\n<p id=\"fs-id2453488\">The process of <strong>normal expiration <\/strong>is passive, meaning that energy is not required to push air out of the lungs.<\/p>\n<ul>\n<li>The elasticity of the lung tissue causes the lung to recoil, as the diaphragm and intercostal muscles relax following inspiration.<\/li>\n<li>The thoracic cavity and lungs decrease in volume, causing an increase in intrapulmonary pressure. The intrapulmonary pressure rises above atmospheric pressure, creating a pressure gradient that causes air to leave the lungs.<\/li>\n<\/ul>\n<p id=\"fs-id2327717\">There are different types, or modes, of breathing that require a slightly different process to allow inspiration and expiration:<\/p>\n<ul>\n<li><strong> Quiet breathing<\/strong>, also known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_218\">eupnea<\/a>, is a mode of breathing that occurs at rest and does not require the cognitive thought of the individual. During quiet breathing, the diaphragm and external intercostals must contract.<\/li>\n<li><strong>Diaphragmatic breathing<\/strong>, also known as deep breathing, requires the diaphragm to contract. As the diaphragm relaxes, air passively leaves the lungs.<\/li>\n<li><strong>Costal<\/strong> <strong>breathing<\/strong>, also known as a shallow breath, requires contraction of the intercostal muscles. As the intercostal muscles relax, air passively leaves the lungs.<\/li>\n<li><strong>Forced breathing<\/strong>, also known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_344\">hyperpnea<\/a>, is a mode of breathing that can occur during exercise or actions that require the active manipulation of breathing, such as singing.\n<ul>\n<li>During forced breathing, inspiration and expiration both occur due to muscle contractions. In addition to the contraction of the diaphragm and intercostal muscles, other accessory muscles must also contract.\n<ul>\n<li>During <strong>forced inspiration<\/strong>, muscles of the neck contract and lift the thoracic wall, increasing lung volume.<\/li>\n<li>During <strong>forced expiration<\/strong>, accessory muscles of the abdomen contract, forcing abdominal organs upward against the diaphragm. This helps to push the diaphragm further into the thorax, pushing more air out. In addition, accessory muscles help to compress the rib cage, which also reduces the volume of the thoracic cavity.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Concept Check<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Breathing normally, place your hand on your stomach and take in one full respiratory cycle.\n<ul>\n<li>What type of breathing are you doing?<\/li>\n<\/ul>\n<\/li>\n<li>Keeping your hand on your stomach, take in one large breath and exhale.\n<ul>\n<li>What type of breathing are you doing?<\/li>\n<\/ul>\n<\/li>\n<li>Complete 10 jumping jacks. Once completed, place your hand on your stomach and take in one full respiratory cycle.\n<ul>\n<li>What type of breathing are you doing?<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/section>\n<section id=\"fs-id2308596\">\n<div id=\"fs-id2005739\" class=\"note anatomy interactive\">\n<h3 id=\"fs-id1368768\">Respiratory Rate and Control of Ventilation<\/h3>\n<\/div>\n<\/section>\n<section id=\"fs-id2129879\">\n<p id=\"fs-id2278288\">Breathing usually occurs without thought, although at times you can consciously control it, such as when you swim under water, sing a song, or blow bubbles. The respiratory rate is the total number of breaths that occur each minute. Respiratory rate can be an important indicator of disease, as the rate may increase or decrease during an illness or in a disease condition. The respiratory rate is controlled by the respiratory center located within the medulla oblongata in the brain, which responds primarily to changes in carbon dioxide, oxygen, and pH levels in the blood.<\/p>\n<p id=\"fs-id2100118\">The normal respiratory rate of a child decreases from birth to adolescence:<\/p>\n<ul>\n<li>A child under 1 year of age has a normal respiratory rate between 30 and 60 breaths per minute.<\/li>\n<li>By the time a child is about 10 years old, the normal rate is closer to 18 to 30.<\/li>\n<li>By adolescence, the normal respiratory rate is similar to that of adults, 12 to 18 breaths per minute.<\/li>\n<\/ul>\n<\/section>\n<section>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Did you know?<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p>Respiratory rate is the total number of breaths that occur each minute.<\/p>\n<\/div>\n<\/div>\n<h3>Watch this video:<\/h3>\n<div class=\"textbox shaded\">\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"Respiratory System, Part 2: Crash Course Anatomy &amp; Physiology #32\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/Cqt4LjHnMEA?feature=oembed&#38;rel=0&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><em>Media 12.1. <a href=\"https:\/\/youtu.be\/Cqt4LjHnMEA\">Respiratory System, Part 2: Crash Course A&amp;P #32<\/a> [Online video]. Copyright 2015 by <a href=\"https:\/\/www.youtube.com\/channel\/UCX6b17PVsYBQ0ip5gyeme-Q\">CrashCourse<\/a>.<\/em><\/p>\n<\/div>\n<h2>Practice Terms Related to the Respiratory System<\/h2>\n<p>&nbsp;<\/p>\n<div id=\"h5p-74\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-74\" class=\"h5p-iframe\" data-content-id=\"74\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: Terms not easily broken down into word parts\"><\/iframe><\/div>\n<\/div>\n<h2>Common Abbreviations for the Respiratory System<\/h2>\n<p>Many terms and phrases related to the respiratory system are abbreviated. Learn these common abbreviations by expanding the list below.<\/p>\n<p>&nbsp;<\/p>\n<div id=\"h5p-75\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-75\" class=\"h5p-iframe\" data-content-id=\"75\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Common Abbreviations for the Respiratory System\"><\/iframe><\/div>\n<\/div>\n<\/section>\n<section>\n<section id=\"fs-id2167754\">\n<h2>Diseases and Disorders of the Respiratory System<\/h2>\n<p>A variety of diseases can affect the respiratory system, such as asthma, emphysema, chronic obstructive pulmonary disorder (COPD), and lung cancer. All of these conditions affect the gas exchange process and result in labored breathing and other difficulties.<\/p>\n<h3>The Effects of Second-Hand Tobacco Smoke<\/h3>\n<\/section>\n<section>The burning of a tobacco cigarette creates multiple chemical compounds that are released through mainstream smoke, which is inhaled by the smoker, and through sidestream smoke, which is the smoke that is given off by the burning cigarette. <strong>Second-hand smoke<\/strong>, which is a combination of sidestream smoke and the mainstream smoke that is exhaled by the smoker, has been demonstrated by numerous scientific studies to cause disease. At least 40 chemicals in sidestream smoke have been identified that negatively impact human health, leading to the development of cancer or other conditions, such as immune system dysfunction, liver toxicity, cardiac <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_411\">arrhythmias<\/a>, pulmonary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_238\">edema<\/a>, and neurological dysfunction. Tobacco and second-hand smoke are considered to be <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_274\">carcinogenic<\/a><span style=\"font-size: 1em\">. Exposure to second-hand smoke can cause lung cancer in individuals who are not tobacco users themselves.<\/span><\/section>\n<section><\/section>\n<ul>\n<li>It is estimated that the risk of developing lung cancer is increased by up to 30% in nonsmokers who live with an individual who smokes in the house, as compared to nonsmokers who are not regularly exposed to second-hand smoke.<\/li>\n<li>Children who live with an individual who smokes inside the home have a larger number of lower respiratory infections, which are associated with hospitalizations, and higher risk of sudden infant death syndrome (SIDS). Second-hand smoke in the home has also been linked to a greater number of ear infections in children, as well as worsening symptoms of asthma.<\/li>\n<\/ul>\n<section><\/section>\n<section><\/section>\n<\/section>\n<\/section>\n<div class=\"note anatomy disorders\">\n<h3>Chronic Obstructive Pulmonary Disease (COPD)<\/h3>\n<p>COPD is a term used to represent a number of respiratory diseases, including chronic bronchitis and emphysema. COPD is a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_243\">chronic<\/a> condition with most symptoms appearing in middle-aged or older adults. Signs and symptoms include shortness of breath, cough, and sputum production. There is no cure for COPD. Shortness of breath may be controlled with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_358\">bronchodilators<\/a>. The best plan is to avoid triggers and getting sick. Clients with COPD are advised to avoid people who are sick, get vaccinated against influenza and pneumococcal pneumonia, and reduce their exposure to pollution and cigarette smoke. <span style=\"font-size: 1em\">While there are several risk factors, as many as 75% <\/span>of cases are associated with cigarette smoking <span style=\"text-align: initial;font-size: 1em\">(National Heart, Lung, and Blood Institute, n.d.)<\/span><span style=\"font-size: 1em\">. <\/span><span style=\"text-align: initial;font-size: 1em\">To learn more about COPD, visit the <a href=\"https:\/\/www.nhlbi.nih.gov\/health-topics\/copd\">National Heart, Lung, and Blood Institute&#8217;s web page<\/a>.<\/span><\/p>\n<h3>Asthma<\/h3>\n<\/div>\n<div id=\"fs-id2279663\" class=\"note anatomy diseases\">\n<p>Asthma is a chronic disease characterized by inflammation, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_238\">edema<\/a> of the airway, and bronchospasms which can inhibit air from entering the lungs. Bronchospasms can lead to an \u201casthma attack.\u201d An attack may be triggered by environmental factors such as dust, pollen, pet hair, or dander, changes in the weather, mold, tobacco smoke, and respiratory infections, or by exercise and stress.<\/p>\n<p>Signs and symptoms of an asthma attack involve coughing, shortness of breath, wheezing, and tightness of the chest. Symptoms of a severe asthma attack require immediate medical attention and may include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_295\">dyspnea<\/a> that results in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_345\">cyanotic<\/a> lips or face, confusion, drowsiness, a rapid pulse, sweating, and severe anxiety. The severity of the condition, frequency of attacks, and identified triggers influence the type of medication that an individual may require. Longer-term treatments are used for those with more severe asthma. Short-term, fast-acting drugs that are used to treat an asthma attack are typically administered via an inhaler. For young children or individuals who have difficulty using an inhaler, asthma medications can be administered via a nebulizer.<\/p>\n<h3>Lung Cancer<\/h3>\n<\/div>\n<p>Lung cancer is a leading cause of cancer death among men and women. Smoking is the most significant risk factor for lung cancer, with 90% of cases in men and 80% of cases in women attributed to tobacco smoking. Signs and symptoms may include shortness of breath, wheezing, blood in the mucus, hoarseness, and trouble swallowing (MedlinePlus, n.d.).<\/p>\n<p>There are two types of lung cancer, <strong>small cell lung cancer (SCLC)<\/strong> and non-small cell lung cancer (NSCLC). Both cancers occur when <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_626\">malignant<\/a> cells form in the tissues of the lung. If <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_571\">metastasis<\/a> occurs, lung cancer cells spread to other parts of the body. Treatment will depend on the type of lung cancer and the stage at diagnosis. Treatments may include surgery, chemotherapy, targeted therapy, immunotherapy, and radiation therapy (National Cancer Institute, 2021a, 2021b).<\/p>\n<div class=\"note anatomy interactive\">\n<section>\n<section>\n<div id=\"fs-id1273237\" class=\"note anatomy disorders\">\n<h3 id=\"fs-id1983836\">Sleep Apnea<\/h3>\n<p>Sleep apnea is a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_144_243\">chronic<\/a> disorder that occurs in children and adults. It is characterized by the cessation of breathing during sleep. These episodes may last for several seconds or several minutes, and may differ in the frequency with which they are experienced. Sleep apnea leads to poor sleep. Signs and symptoms include fatigue, evening napping, irritability, memory problems, morning headaches, and excessive snoring. A diagnosis of sleep apnea is usually done during a sleep study, where the patient is monitored in a sleep laboratory for several nights. <span style=\"text-align: initial;font-size: 1em\">Treatment of sleep apnea commonly includes the use of a device called a <\/span><strong style=\"text-align: initial;font-size: 1em\">continuous positive airway pressure (CPAP) machine<\/strong><span style=\"text-align: initial;font-size: 1em\"> during sleep. The CPAP machine has a mask that covers the nose, or the nose and mouth, and forces air into the airway at regular intervals. This pressurized air can help to gently force the airway to remain open, allowing more normal ventilation to occur.<\/span><\/p>\n<\/div>\n<\/section>\n<\/section>\n<h2>Medical Terms in Context<\/h2>\n<div id=\"h5p-76\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-76\" class=\"h5p-iframe\" data-content-id=\"76\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: History and Physical Examination\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-77\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-77\" class=\"h5p-iframe\" data-content-id=\"77\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: Consultation Report #1\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-78\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-78\" class=\"h5p-iframe\" data-content-id=\"78\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: Consultation Report #2\"><\/iframe><\/div>\n<\/div>\n<h2>Medical Specialties and Procedures Related to the Respiratory System<\/h2>\n<h3>Respiratory Therapists (RTs)<\/h3>\n<p>Respiratory therapists (RTs) are healthcare professionals that monitor, assess, and treat people who are having problems breathing. RTs must have at least a two-year degree. RTs measure lung capacity, test oxygen and carbon dioxide levels, perform chest physiotherapy to remove mucus from patients&#8217; lungs, and operate ventilator equipment (Bureau of Labor Statistics, 2021). For more information, visit the <a href=\"https:\/\/www.aarc.org\/careers\/what-is-an-rt\/\">American Association for Respiratory Care web page<\/a>.<\/p>\n<h3>Thoracic Surgeon<\/h3>\n<p>A thoracic surgeon refers to a surgeon who has specialized in either thoracic (chest) surgery or cardiothoracic (heart and chest) surgery (National Cancer Institute, n.d.). To learn about the career path, read <a href=\"https:\/\/www.sts.org\/sites\/default\/files\/documents\/ResidentsFAQ_FINAL_06042018.pdf\">this PDF from The Society of Thoracic Surgeons.<\/a><\/p>\n<h3>Spirometry Testing<\/h3>\n<\/div>\n<section id=\"fs-id810328\" class=\"summary\"><\/section>\n<section id=\"fs-id2345620\" class=\"interactive-exercise\">\n<div id=\"fs-id2522180\" class=\"exercise\">\n<div id=\"fs-id2801773\" class=\"problem\">\n<section class=\"summary\">\n<p id=\"fs-id2626519\">Spirometry testing is used to find out how well lungs are working by measuring air volume.<\/p>\n<ul>\n<li><strong>Respiratory volume<\/strong> describes the amount of air in a given space within the lungs, or which can be moved by the lung, and is dependent on a variety of factors.<\/li>\n<li><strong>Tidal volume <\/strong>refers to the amount of air that enters the lungs during quiet breathing, whereas inspiratory reserve volume is the amount of air that enters the lungs when a person inhales past the tidal volume.<\/li>\n<li><strong>Expiratory reserve volume<\/strong> is the extra amount of air that can leave with forceful expiration, following tidal expiration.<\/li>\n<li><strong>Residual volume<\/strong> is the amount of air that is left in the lungs after expelling the expiratory reserve volume.<\/li>\n<li><strong>Respiratory capacity <\/strong>is the combination of two or more volumes.<\/li>\n<li><strong> Anatomical dead space<\/strong> refers to the air within the respiratory structures that never participates in gas exchange, because it does not reach functional alveoli.<\/li>\n<li><strong> Respiratory rate <\/strong>is the number of breaths taken per minute, which may change during certain diseases or conditions.<\/li>\n<\/ul>\n<p id=\"fs-id2590391\">Both respiratory rate and depth are controlled by the respiratory centers of the brain, which are stimulated by factors such as chemical and pH changes in the blood. These changes are sensed by central chemoreceptors, which are located in the brain, and peripheral chemoreceptors, which are located in the aortic arch and carotid arteries. A rise in carbon dioxide or a decline in oxygen levels in the blood stimulates an increase in respiratory rate and depth.<\/p>\n<h4>Watch this video:<\/h4>\n<div class=\"textbox shaded\">\n<p><iframe loading=\"lazy\" id=\"oembed-3\" title=\"Peak Flow and Spirometry - Lung Function Tests\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/M4C8EInOMOI?feature=oembed&#38;rel=0&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><em>Media 12.3. <a href=\"http:\/\/youtube.com\/watch?v=M4C8EInOMOI\">Peak Flow and Spirometry &#8211; Lung Function Tests<\/a> [Online video]. Copyright 2012 by <a href=\"https:\/\/www.youtube.com\/channel\/UCh4bLGk7imxI7fWyk01c8fA\">Oxford Medical Education<\/a>.<\/em><\/p>\n<\/div>\n<h2>Respiratory System Vocabulary<\/h2>\n<\/section>\n<\/div>\n<\/div>\n<\/section>\n<div class=\"note anatomy interactive\">\n<p><strong>Adenoidectomy<\/strong><\/p>\n<p>Excision of the adenoids.<\/p>\n<p><strong>Alveolar duct<\/strong><\/p>\n<p>Small tube that leads from the terminal bronchiole to the respiratory bronchiole and is the point of attachment for alveoli.<\/p>\n<p><strong>Alveolitis<\/strong><\/p>\n<p>Inflammation of the alveoli.<\/p>\n<p><strong>Aphonia<\/strong><\/p>\n<p>Condition of the absence of one&#8217;s voice.<\/p>\n<p><strong>Apnea<\/strong><\/p>\n<p>A temporary absence of respiration.<\/p>\n<p><strong>Asphyxia<\/strong><\/p>\n<p>Condition caused by a lack of oxygen that leads to impending or actual death.<\/p>\n<p><strong>Aspirate<\/strong><\/p>\n<p>To withdraw fluid, tissue, or other substances from a body cavity, cyst, or tumor.<\/p>\n<p><strong>Atelectasis<\/strong><\/p>\n<p>Failure of the lung to expand (inflate) completely.<\/p>\n<p><strong>Autonomic<\/strong><\/p>\n<p>Involuntary or unconscious.<\/p>\n<p><strong>Benign<\/strong><\/p>\n<p>Non-cancerous.<\/p>\n<p><strong>Bronchiectasis<\/strong><\/p>\n<p>Dilation of the bronchi.<\/p>\n<p><strong>Bronchitis<\/strong><\/p>\n<p>Inflammation of the bronchus.<\/p>\n<p><strong>Bronchodilators<\/strong><\/p>\n<p>A type of drug that causes small airways in the lungs to open up.<\/p>\n<p><strong>Bronchogenic carcinoma<\/strong><\/p>\n<p>Cancer that begins in the tissue that lines or covers the airways of the lungs, including small cell and non-small cell lung cancer.<\/p>\n<p><strong>Bronchopneumonia<\/strong><\/p>\n<p>Inflammation of the lung, particularly the bronchioles and alveoli, that is associated with bronchitis.<\/p>\n<p><strong>Bronchoscope<\/strong><\/p>\n<p>A thin, tube-like instrument used to examine the inside of the trachea, bronchi, and lungs.<\/p>\n<p><strong>Bronchoscopy<\/strong><\/p>\n<p>A procedure involving a bronchoscope to examine the inside of the trachea, bronchi, and lungs.<\/p>\n<p><strong>Bronchospasm<\/strong><\/p>\n<p>Spasmodic contraction of the smooth muscle of the bronchi.<\/p>\n<p><strong>Carcinogen<\/strong><\/p>\n<p>Any substance that causes cancer.<\/p>\n<p><strong>Cardiac notch<\/strong><\/p>\n<p>An indentation on the surface of the left lung.<\/p>\n<p><strong>Carina<\/strong><\/p>\n<p>A ridge at the base of the trachea (windpipe) that separates the openings of the right and left main bronchi (the large air passages that lead from the trachea to the lungs).<\/p>\n<p><strong>Chronic<\/strong><\/p>\n<p>A condition that lasts a long time with periods of remission and exacerbation.<\/p>\n<p><strong>Computerized tomography (CT)<\/strong><\/p>\n<p>A noninvasive imaging technique that uses computers to analyze several cross-sectional X-rays in order to reveal minute details about structures in the body.<\/p>\n<p><strong>Conducting zone<\/strong><\/p>\n<p>The major functions of the conducting zone are to provide a route for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air.<\/p>\n<p><strong>Cyanotic<\/strong><\/p>\n<p>Pertaining to abnormal color of blue (bluish color, lips and nail beds) caused by deoxygenation.<\/p>\n<p><strong>Defensins<\/strong><\/p>\n<p>The lysozyme enzyme and proteins which have antibacterial properties.<\/p>\n<p><strong>Diaphragm<\/strong><\/p>\n<p>A sheet of skeletal muscle separating the thoracic and abdominal cavities that has to contract and relax for you to breathe.<\/p>\n<p><strong>Dysphonia<\/strong><\/p>\n<p>Condition of difficult speaking, including hoarseness and change in pitch or quality of the voice.<\/p>\n<p><strong>Dyspnea<\/strong><\/p>\n<p>Difficulty breathing.<\/p>\n<p><strong>Epiglottitis<\/strong><\/p>\n<p>Inflammation of the epiglottis.<\/p>\n<p><strong>Endoscope<\/strong><\/p>\n<p>A thin, tube-like instrument used to look at tissues inside the body.<\/p>\n<p><strong>Endoscopy<\/strong><\/p>\n<p>A procedure that uses an endoscope to examine the inside of the body.<\/p>\n<p><strong>Epiglottis<\/strong><\/p>\n<p>Leaf-shaped piece of elastic cartilage that is a portion of the larynx that swings to close the trachea during swallowing.<\/p>\n<p><strong>Epistaxis<\/strong><\/p>\n<p>Nosebleed.<\/p>\n<p><strong>Erythrocytes<\/strong><\/p>\n<p>Red blood cells.<\/p>\n<p><strong>Eupnea<\/strong><\/p>\n<p>A mode of breathing that occurs at rest and does not require the cognitive thought of the individual; also known as quiet breathing.<\/p>\n<p><strong>Expiration<\/strong><\/p>\n<p>Exhalation, or the process of causing air to leave the lungs.<\/p>\n<p><strong>External nose<\/strong><\/p>\n<p>The surface and skeletal structures that result in the outward appearance of the nose and contribute to its numerous functions.<\/p>\n<p><strong>Fauces<\/strong><\/p>\n<p>The opening of the oral cavity into the pharynx.<\/p>\n<p><strong>Fibroelastic membrane<\/strong><\/p>\n<p>A flexible membrane that closes the posterior surface of the trachea, connecting the C-shaped cartilages.<\/p>\n<p><strong>Glottis<\/strong><\/p>\n<p>Composed of the vestibular folds, the true vocal cords, and the space between these folds.<\/p>\n<p><strong>Hard palate<\/strong><\/p>\n<p>Located at the anterior region of the nasal cavity and is composed of bone.<\/p>\n<p><strong>Hemothorax<\/strong><\/p>\n<p>Hemorrhage within the pleural cavity.<\/p>\n<p><strong>Hematologist<\/strong><\/p>\n<p>A doctor who has special training in diagnosing and treating blood disorders.<\/p>\n<p><strong>Hematology<\/strong><\/p>\n<p>The study of blood and blood-forming issues.<\/p>\n<p><strong>Hilum of the lung<\/strong><\/p>\n<p>A concave region where blood vessels, lymphatic vessels, and nerves also enter the lungs.<\/p>\n<p><strong>Hypercapnia<\/strong><\/p>\n<p>Abnormally elevated blood levels of CO<sub>2 <\/sub>(carbon dioxide).<\/p>\n<p><strong>Hyperpnea<\/strong><\/p>\n<p>Forced breathing or breathing that is excessive.<\/p>\n<p><strong>Hypocapnia<\/strong><\/p>\n<p>Abnormally low blood levels of CO<sub>2 <\/sub>(carbon dioxide).<\/p>\n<p><strong>Hypoxemia<\/strong><\/p>\n<p>Below-normal level of oxygen saturation of blood (typically &lt;95 percent).<\/p>\n<p><strong>Hypoxia<\/strong><\/p>\n<p>Lack of oxygen supply to the tissues.<\/p>\n<p><strong>Inferior<\/strong><\/p>\n<p>A position below or lower than another part of the body proper.<\/p>\n<p><strong>Influenza (flu)<\/strong><\/p>\n<p>An acute viral infection involving the respiratory tract.<\/p>\n<p><strong>Inspiration<\/strong><\/p>\n<p>Inhalation, or process of breathing air into the lungs.<\/p>\n<p><strong>Laryngeal<\/strong><\/p>\n<p>Pertaining to the larynx.<\/p>\n<p><strong>Laryngitis<\/strong><\/p>\n<p>Inflammation of the larynx.<\/p>\n<p><strong>Laryngopharynx<\/strong><\/p>\n<p>One of the three regions of the pharynx; inferior to the oropharynx and posterior to the larynx.<\/p>\n<p><strong>Laryngoplasty<\/strong><\/p>\n<p>Surgical repair of the larynx.<\/p>\n<p><strong>Laryngoscope<\/strong><\/p>\n<p>A thin, tube-like instrument used to examine the larynx.<\/p>\n<p><strong>Laryngoscopy<\/strong><\/p>\n<p>Examination of the larynx with a mirror or laryngoscope.<\/p>\n<p><strong>Larynx<\/strong><\/p>\n<p>A cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs; also known as the voice box.<\/p>\n<p><strong>Lobectomy<\/strong><\/p>\n<p>Excision of the lobe(s) of an organ.<\/p>\n<p><strong>Lymphocytes<\/strong><\/p>\n<p>The second most common type of leukocyte and are essential for the immune response.<\/p>\n<p><strong>Malignant<\/strong><\/p>\n<p>Cancerous.<\/p>\n<p><strong>Mucus<\/strong><\/p>\n<p>A thick, slippery fluid made by the membranes that line certain organs of the body.<\/p>\n<p><strong>Nasopharyngitis<\/strong><\/p>\n<p>Inflammation of the nose and pharynx.<\/p>\n<p><strong>Nasopharynx<\/strong><\/p>\n<p>The upper part of the throat behind the nose. An opening on each side of the nasopharynx leads into the ear.<\/p>\n<p><strong>Nebulizer<\/strong><\/p>\n<p>A device used to turn liquid into a fine spray.<\/p>\n<p><strong>Nosocomial infection<\/strong><\/p>\n<p>Infection acquired in hospital.<\/p>\n<p><strong>Oropharynx<\/strong><\/p>\n<p>A passageway for both air and food; borders the nasopharynx and the oral cavity.<\/p>\n<p><strong>Oximeter<\/strong><\/p>\n<p>Instrument used to measure the oxygenation of tissues.<\/p>\n<p><strong>Pharyngeal tonsil<\/strong><\/p>\n<p>The tonsil located at the back of the throat; also known as the adenoid when swollen.<\/p>\n<p><strong>Pharyngitis<\/strong><\/p>\n<p>Inflammation of the pharynx.<\/p>\n<p><strong>Pharynx<\/strong><\/p>\n<p>A tube formed by skeletal muscle and lined by mucous membrane that is continuous with that of the nasal cavities; also known as the throat.<\/p>\n<p><strong>Pleural effusion<\/strong><\/p>\n<p>An abnormal collection of fluid between the thin layers of tissue (pleura) lining the lung and the wall of the chest cavity.<\/p>\n<p><strong>Pleurisy<\/strong><\/p>\n<p>Inflammation of the pleura.<\/p>\n<p><strong>Pneumoconiosis<\/strong><\/p>\n<p>A condition caused by the inhalation of dust.<\/p>\n<p><strong>Pneumonectomy<\/strong><\/p>\n<p>Excision of the lung.<\/p>\n<p><strong>Pneumonia<\/strong><\/p>\n<p>A severe inflammation of the lungs in which the alveoli (tiny air sacs) are filled with fluid.<\/p>\n<p><strong>Pneumothorax<\/strong><\/p>\n<p>An abnormal collection of air in the space between the thin layer of tissue that covers the lungs and the chest cavity that can cause all or part of the lung to collapse.<\/p>\n<p><strong>Polysomnography (PSG)<\/strong><\/p>\n<p>Simultaneous and continuous monitoring of several parameters during sleep to study normal and abnormal sleep.<\/p>\n<p><strong>Posterior<\/strong><\/p>\n<p>Describes the back or direction toward the back of the body.<\/p>\n<p><strong>Pulmonary artery<\/strong><\/p>\n<p>Artery that arises from the pulmonary trunk.<\/p>\n<p><strong>Pulmonary edema<\/strong><\/p>\n<p>Fluid accumulation in alveoli and bronchioles (related to heart failure).<\/p>\n<p><strong>Pulmonary embolism\u00a0<\/strong><\/p>\n<p>A blood clot within the lung.<\/p>\n<p><strong>Radiologist<\/strong><\/p>\n<p>A doctor who has special training in creating and interpreting pictures of areas inside the body.<\/p>\n<p><strong>Radiography<\/strong><\/p>\n<p>A procedure that uses x-rays to take pictures of areas inside the body.<\/p>\n<p><strong>Radiology<\/strong><\/p>\n<p>The use of radiation or other imaging technologies to diagnose or treat disease.<\/p>\n<p><strong>Respiratory zone<\/strong><\/p>\n<p>The respiratory zone includes structures that are directly involved in gas exchange.<\/p>\n<p><strong>Rhinitis<\/strong><\/p>\n<p>Inflammation of the mucous membranes of the nose.<\/p>\n<p><strong>Rhinoplasty<\/strong><\/p>\n<p>A plastic surgical operation on the nose, either reconstructive, restorative, or cosmetic.<\/p>\n<p><strong>Rhinorrhea <\/strong><\/p>\n<p>Excess nasal drainage; also called a &#8220;runny nose.&#8221;<\/p>\n<p><strong>Septal cartilage <\/strong><\/p>\n<p>The flexible hyaline cartilage connected to the nasal bone.<\/p>\n<p><strong>Sinusitis<\/strong><\/p>\n<p>Inflammation of the sinuses.<\/p>\n<p><strong>Soft palate<\/strong><\/p>\n<p>Located at the posterior portion of the nasal cavity and consists of muscle tissue.<\/p>\n<p><strong>Sonogram<\/strong><\/p>\n<p>A computer picture of areas inside the body created by high-energy sound waves.<\/p>\n<p><strong>Spirometry<\/strong><\/p>\n<p>The measurement of volume of air inhaled or exhaled by the lung.<\/p>\n<p><strong>Sputum<\/strong><\/p>\n<p>Mucus and other matter brought up from the lungs by coughing.<\/p>\n<p><strong>Stethoscope<\/strong><\/p>\n<p>An instrument is used to hear sounds produced by the heart, lungs, or other parts of the body.<\/p>\n<p><strong>Sympathetic nervous system (SNS)<\/strong><\/p>\n<p>The division of the nervous system involved in our fight-or-flight responses. It continuously monitors body temperature and initiates appropriate motor responses.<\/p>\n<p><strong>Tachypnea<\/strong><\/p>\n<p>Rapid breathing.<\/p>\n<p><strong>Thoracalgia<\/strong><\/p>\n<p>Pain in the chest.<\/p>\n<p><strong>Thoracentesis<\/strong><\/p>\n<p>Removal of fluid from the pleural cavity through a needle inserted between the ribs.<\/p>\n<p><strong>Thoracic<\/strong><\/p>\n<p>Pertaining to the chest.<\/p>\n<p><strong>Thoracoscope<\/strong><\/p>\n<p>A thin tube-like instrument used to examine the inside of the chest.<\/p>\n<p><strong>Thoracoscopy<\/strong><\/p>\n<p>Examination of the inside of the chest, using a thoracoscope.<\/p>\n<p><strong>Thoracotomy<\/strong><\/p>\n<p>An operation to open the chest.<\/p>\n<p><strong>Tonsillectomy<\/strong><\/p>\n<p>Excision of the tonsils.<\/p>\n<p><strong>Tonsillitis<\/strong><\/p>\n<p>Inflammation of the tonsils.<\/p>\n<p><strong>Tracheitis<\/strong><\/p>\n<p>Inflammation of the trachea.<\/p>\n<p><strong>Tracheostomy<\/strong><\/p>\n<p>Surgery to create an opening into the trachea.<\/p>\n<p><strong>Tracheotomy<\/strong><\/p>\n<p>Surgical incision of the trachea.<\/p>\n<p><strong>Trachea<\/strong><\/p>\n<p>The windpipe.<\/p>\n<p><strong>Upper respiratory infection<\/strong><\/p>\n<p>Infection of the nasal cavity, pharynx and larynx cause by a virus.<\/p>\n<p><strong>Uvula <\/strong><\/p>\n<p>A small bulbous, teardrop-shaped structure located at the apex of the soft palate.<\/p>\n<p><strong>Ventilator<\/strong><\/p>\n<p>A machine used to help a patient breathe.<\/p>\n<\/div>\n<h2><strong>Test Yourself<\/strong><\/h2>\n<div id=\"h5p-79\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-79\" class=\"h5p-iframe\" data-content-id=\"79\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Respiratory System: Test Yourself\"><\/iframe><\/div>\n<\/div>\n<h2>References<\/h2>\n<p>Bureau of Labor Statistics. (2021). Respiratory therapists. In <em>Occupational outlook handbook<\/em>. U.S. Department of Labor. <a href=\"https:\/\/www.bls.gov\/ooh\/healthcare\/respiratory-therapists.htm\">https:\/\/www.bls.gov\/ooh\/healthcare\/respiratory-therapists.htm<\/a><\/p>\n<p>CrashCourse. (2015, August 24). <em>Respiratory system, part 1: crash course A&amp;P #31<\/em> [Video]. YouTube. <a href=\"https:\/\/youtu.be\/bHZsvBdUC2I\">https:\/\/youtu.be\/bHZsvBdUC2I<\/a><\/p>\n<p>CrashCourse. (2015, August 31). <em>Respiratory system, part 2: crash course A&amp;P #32<\/em> [Video]. YouTube. <a href=\"https:\/\/youtu.be\/Cqt4LjHnMEA\">https:\/\/youtu.be\/Cqt4LjHnMEA<\/a><\/p>\n<p>National Cancer Institute. (n.d.). <em>Thoracic surgeon definition<\/em>. National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.cancer.gov\/publications\/dictionaries\/cancer-terms\/def\/thoracic-surgeon\">https:\/\/www.cancer.gov\/publications\/dictionaries\/cancer-terms\/def\/thoracic-surgeon<\/a><\/p>\n<p>National Cancer Institute. (2021a). <em>Non-small cell lung cancer treatment (PDQ\u00ae)-Patient version<\/em>. National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.cancer.gov\/types\/lung\/patient\/non-small-cell-lung-treatment-pdq\">https:\/\/www.cancer.gov\/types\/lung\/patient\/non-small-cell-lung-treatment-pdq<\/a><\/p>\n<p>National Cancer Institute. (2021b). <em>Small cell cancer treatment (PDQ\u00ae)-Patient version<\/em>. National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.cancer.gov\/types\/lung\/patient\/small-cell-lung-treatment-pdq\">https:\/\/www.cancer.gov\/types\/lung\/patient\/small-cell-lung-treatment-pdq<\/a><\/p>\n<p>National Heart, Lung, and Blood Institute. (n.d.). <em>COPD.<\/em> National Institutes of Health, U.S. Department of Health. <a href=\"https:\/\/www.nhlbi.nih.gov\/health-topics\/copd\">https:\/\/www.nhlbi.nih.gov\/health-topics\/copd<\/a><\/p>\n<p>Oxford Medical Education. (2012, May 13). <em>Peak flow and spirometry &#8211; Lung function tests<\/em> [Video]. YouTube. <a href=\"https:\/\/www.youtube.com\/watch?v=M4C8EInOMOI\">https:\/\/www.youtube.com\/watch?v=M4C8EInOMOI<\/a><\/p>\n<h2>Image Descriptions<\/h2>\n<p><a id=\"Figure12.1id\" href=\"\"><\/a><strong>Figure 12.1 image description:<\/strong> This figure shows the upper half of the human body. The major organs in the respiratory system are labeled. <a href=\"#Figure12.1\">[Return to Figure 12.1].<\/a><\/p>\n<p><a id=\"Figure12.2id\" href=\"\"><\/a><strong>Figure 12.2 image description:<\/strong> This figure shows a cross section view of the nose and throat. The major parts are labeled. <a href=\"#Figure12.2\">[Return to Figure 12.2].<\/a><\/p>\n<p><a id=\"Figure12.3id\" href=\"\"><\/a><strong>Figure 12.3 image description:<\/strong> This figure shows a micrograph of pseudostratified epithelium. <a href=\"#Figure12.3\">[Return to Figure 12.3].<\/a><\/p>\n<p><a id=\"Figure12.4id\" href=\"\"><\/a><strong>Figure 12.4 image description:<\/strong> This figure shows the side view of the face. The different parts of the pharynx are color-coded and labeled (from the top): nasal cavity, hard palate, soft palate, tongue, epiglottis, larynx, esophagus, trachea. <a href=\"#Figure12.4\">[Return to Figure 12.4].<\/a><\/p>\n<p><a id=\"Figure12.5id\" href=\"\"><\/a><strong>Figure 12.5 image description:<\/strong> The top panel of this figure shows the anterior view of the larynx, and the bottom panel shows the right lateral view of the larynx. <a href=\"#Figure12.5\">[Return to Figure 12.5].<\/a><\/p>\n<p><a id=\"Figure12.6id\" href=\"\"><\/a><strong>Figure 12.6 image description:<\/strong> This diagram shows the cross-section of the larynx. The different types of cartilages are labeled (clockwise from top): pyriform fossa, true vocal cord, epiglottis, tongue, glottis, vestibular fold, trachea, esophagus. <a href=\"#Figure12.6\">[Return to Figure 12.6].<\/a><\/p>\n<p><a id=\"Figure12.7id\" href=\"\"><\/a><strong>Figure 12.7 image description:<\/strong> The top panel of this figure shows the trachea and its organs. The major parts including the larynx, trachea, bronchi, and lungs are labeled. <a href=\"#Figure12.7\">[Return to Figure 12.7].<\/a><\/p>\n<p><a id=\"Figure12.8id\" href=\"\"><\/a><strong>Figure 12.8 image description:<\/strong> This image shows the bronchioles and alveolar sacs in the lungs and depicts the exchange of oxygenated and deoxygenated blood in the pulmonary blood vessels. <a href=\"#Figure12.8\">[Return to Figure 12.8].<\/a><\/p>\n<p><a id=\"Figure12.9id\" href=\"\"><\/a><strong>Figure 12.9 image description:<\/strong> This figure shows the detailed structure of the alveolus. The top panel shows the alveolar sacs and the bronchioles. The middle panel shows a magnified view of the alveolus, and the bottom panel shows a micrograph of the cross section of a bronchiole. <a href=\"#Figure12.9\">[Return to Figure 12.9].<\/a><\/p>\n<p><a id=\"Figure12.10id\" href=\"\"><\/a><strong>Figure 12.10 image description:<\/strong> Diagram of the lungs with the major parts labelled (from top, clockwise): trachea, superior lobe, main bronchus, lobar bronchus, segmental bronchus, inferior lobe, inferior lobe, middle lobe, superior lobe of the left lung. <a href=\"#Figure12.10\">[Return to Figure 12.10].<\/a><\/p>\n<p><a id=\"Figure12.11id\" href=\"\"><\/a><strong>Figure 12.11 image description:<\/strong> This figure shows the lungs and the chest wall, which protects the lungs, in the left panel. In the right panel, a magnified image shows the pleural cavity and a pleural sac. <a href=\"#Figure12.11\">[Return to Figure 12.11].<\/a><\/p>\n<p><a id=\"Figure12.12id\" href=\"\"><\/a><strong>Figure 12.12 image description:<\/strong> The left panel of this image shows a person inhaling air and the location of the chest muscles. The right panel shows the person exhaling air and the contraction of the thoracic cavity. <a href=\"#Figure12.12\">[Return to Figure 12.12].<\/a><\/p>\n<p>&nbsp;<\/p>\n<section class=\"summary\">\n<div class=\"textbox shaded\">Unless otherwise indicated, this chapter contains material adapted from <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction\"><em>Anatomy and Physiology<\/em><\/a> (on <a href=\"https:\/\/openstax.org\/\">OpenStax<\/a>), by Betts et al. and is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY 4.0 international license<\/a>. Download and access this book for free at <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction\">https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction<\/a>.<\/div>\n<p>&nbsp;<\/p>\n<\/section>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_144_259\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_259\"><div tabindex=\"-1\"><p>Involuntary or unconscious (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_301\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_301\"><div tabindex=\"-1\"><p>The surface and skeletal structures that result in the outward appearance of the nose and contribute to its numerous functions (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_546\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_546\"><div tabindex=\"-1\"><p>The nasal cavity (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_302\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_302\"><div tabindex=\"-1\"><p>The flexible hyaline cartilage connected to the nasal bone (Betts, et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_303\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_303\"><div tabindex=\"-1\"><p>Located at the anterior region of the nasal cavity and is composed of bone (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_304\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_304\"><div tabindex=\"-1\"><p>Located at the posterior portion of the nasal cavity and consists of muscle tissue (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_293\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_293\"><div tabindex=\"-1\"><p>Excess nasal drainage; also called a \"runny nose\" (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_307\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_307\"><div tabindex=\"-1\"><p>A tube formed by skeletal muscle and lined by mucous membrane that is continuous with that of the nasal cavities; also known as the throat (Betts, et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_317\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_317\"><div tabindex=\"-1\"><p>pertaining to the pharynx<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_705\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_705\"><div tabindex=\"-1\"><p>The second most common type of leukocyte and are essential for the immune response (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_310\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_310\"><div tabindex=\"-1\"><p>A small bulbous, teardrop-shaped structure located at the apex of the soft palate (Betts, et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_308\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_308\"><div tabindex=\"-1\"><p>The upper part of the throat behind the nose. An opening on each side of the nasopharynx leads into the ear (National Cancer Institute, n.d.)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_311\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_311\"><div tabindex=\"-1\"><p>The oropharynx is a passageway for both air and food and borders the nasopharynx and the oral cavity (Betts, et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_312\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_312\"><div tabindex=\"-1\"><p>The opening of the oral cavity into the pharynx (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_318\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_318\"><div tabindex=\"-1\"><p>pertaining to the tongue<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_321\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_321\"><div tabindex=\"-1\"><p>A position below or lower than another part of the body proper (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_322\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_322\"><div tabindex=\"-1\"><p>Describes the back or direction toward the back of the body (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_398\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_398\"><div tabindex=\"-1\"><p>Often referred to as \"good\" cholesterol (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_313\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_313\"><div tabindex=\"-1\"><p>A cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs; also known as the voice box (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_314\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_314\"><div tabindex=\"-1\"><p>pertaining to the larynx<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_315\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_315\"><div tabindex=\"-1\"><p>A very flexible piece of elastic cartilage attached to the thyroid cartilage that covers the opening of the trachea (Betts. et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_316\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_316\"><div tabindex=\"-1\"><p>The glottis is composed of the vestibular folds, the true vocal cords, and the space between these folds (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_319\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_319\"><div tabindex=\"-1\"><p>The windpipe (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_320\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_320\"><div tabindex=\"-1\"><p>A flexible membrane that closes the posterior surface of the trachea, connecting the C-shaped cartilages (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_341\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_341\"><div tabindex=\"-1\"><p>A ridge at the base of the trachea (windpipe) that separates the openings of the right and left main bronchi (the large air passages that lead from the trachea to the lungs) (National Cancer Institute, n.d.)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_323\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_323\"><div tabindex=\"-1\"><p>A concave region where blood vessels, lymphatic vessels, and nerves also enter the lungs (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_300\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_300\"><div tabindex=\"-1\"><p>The major functions of the conducting zone are to provide a route for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air (Betts, et al., 2013).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_306\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_306\"><div tabindex=\"-1\"><p>The respiratory zone includes structures that are directly involved in gas exchange (Betts, et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_324\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_324\"><div tabindex=\"-1\"><p>Small tube that leads from the terminal bronchiole to the respiratory bronchiole and is the point of attachment for alveoli (Betts. et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_547\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_547\"><div tabindex=\"-1\"><p>A sheet of skeletal muscle separating the thoracic and abdominal cavities that has to contract and relax for you to breathe (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_339\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_339\"><div tabindex=\"-1\"><p>An indentation on the surface of the left lung (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_421\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_421\"><div tabindex=\"-1\"><p>The very large artery referred to as a trunk, a term indicating that the vessel gives rise to several smaller arteries (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_340\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_340\"><div tabindex=\"-1\"><p>Artery that arises from the pulmonary trunk (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_548\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_548\"><div tabindex=\"-1\"><p>Activity that is referred to by the epithet of rest and digest (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_337\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_337\"><div tabindex=\"-1\"><p>The division of the nervous system involved in our fight-or-flight responses. It continuously monitors body temperature and initiates appropriate motor responses (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_342\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_342\"><div tabindex=\"-1\"><p>Inhalation, or process of breathing air into the lungs (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_218\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_218\"><div tabindex=\"-1\"><p>A mode of breathing that occurs at rest and does not require the cognitive thought of the individual; also known as quiet breathing (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_344\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_344\"><div tabindex=\"-1\"><p>Forced breathing or breathing that is excessive (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_411\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_411\"><div tabindex=\"-1\"><p>A deviation from the normal pattern of impulse conduction and contraction of the heart (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_238\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_238\"><div tabindex=\"-1\"><p>Swelling due to excessive liquid in the tissues (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_274\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_274\"><div tabindex=\"-1\"><p>Any substance that causes cancer (National Cancer Institute, n.d.)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_243\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_243\"><div tabindex=\"-1\"><p>A condition that lasts a long time with periods of remission and exacerbation (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_358\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_358\"><div tabindex=\"-1\"><p>A type of drug that causes small airways in the lungs to open up (National Cancer Institute, n.d.)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_295\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_295\"><div tabindex=\"-1\"><p>Difficulty breathing (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_345\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_345\"><div tabindex=\"-1\"><p>Pertaining to abnormal discolouration of blue (bluish colour, lips and nail beds) caused by deoxygenation (National Cancer Institute, n.d.)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_626\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_626\"><div tabindex=\"-1\"><p>Cancerous (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_144_571\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_144_571\"><div tabindex=\"-1\"><p>The process in which cancer spreads from one part of the body to another (Betts et al., 2013)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":32,"menu_order":12,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-144","chapter","type-chapter","status-publish","hentry"],"part":19,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/pressbooks\/v2\/chapters\/144","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/wp\/v2\/users\/32"}],"version-history":[{"count":3,"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/pressbooks\/v2\/chapters\/144\/revisions"}],"predecessor-version":[{"id":1505,"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/pressbooks\/v2\/chapters\/144\/revisions\/1505"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/pressbooks\/v2\/parts\/19"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/pressbooks\/v2\/chapters\/144\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/wp\/v2\/media?parent=144"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/pressbooks\/v2\/chapter-type?post=144"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/wp\/v2\/contributor?post=144"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchpr1040\/wp-json\/wp\/v2\/license?post=144"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}