{"id":5205,"date":"2019-06-24T17:31:55","date_gmt":"2019-06-24T17:31:55","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/18-1-case-study-waste-management-3\/"},"modified":"2023-11-30T23:12:29","modified_gmt":"2023-11-30T23:12:29","slug":"18-1-case-study-waste-management-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/18-1-case-study-waste-management-3\/","title":{"raw":"16.1\u00a0Case Study: Waste Management","rendered":"16.1\u00a0Case Study: Waste Management"},"content":{"raw":"&nbsp;\r\n\r\n[caption id=\"attachment_4697\" align=\"aligncenter\" width=\"400\"]<img class=\"wp-image-4697\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/Gotta-Pee-by-Jon-Eric-Melsaeter-on-Flickr-e1606265012586-2.jpg\" alt=\"Signs for mens and women's washroom. \" width=\"400\" height=\"234\" \/> <em>Figure 16.1.1 Alcohol may increase your visits to the restroom. <\/em>[\/caption]\r\n<h1>Case\u00a0Study: Drink and Flush<\/h1>\r\n\u201cWow, this line for the restroom is long!\u201d Shae says to Talia, anxiously bobbing from side to side to ease the pressure in her bladder. Talia nods and says, \u201cIt\u2019s always like this at parties. It\u2019s the alcohol.\u201d\r\n\r\nShae and Talia are 21-year-old college students at a party. They \u2014 along with the other party guests \u2014 have been drinking alcoholic beverages over the course of the evening. As the night goes on, the line for the restroom has gotten longer and longer. You may have noticed this phenomenon if you have been to places where large numbers of people are drinking alcohol, like at the ballpark in Figure 16.1.2.\r\n\r\n[caption id=\"attachment_4702\" align=\"aligncenter\" width=\"400\"]<img class=\"wp-image-4702\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Bathroom-line-up-by-Dorothy-on-flickr-cc-by-2.jpg\" alt=\"16.1.2 Bathroom Line up\" width=\"400\" height=\"300\" \/> <em>Figure 16.1.2 A line stretching out of a restroom door at a ballpark.<\/em>[\/caption]\r\n\r\nShae says, \u201cI wonder why alcohol makes you have to pee?\u201d Talia says she learned about this in her Human Biology class. She tells Shae that alcohol inhibits a hormone that helps you retain water. Instead of your body retaining water, you urinate more out. This could lead to dehydration, so she suggests that after their trip to the restroom, they start drinking water, instead of alcohol.\r\n\r\nFor people who drink occasionally or moderately, this effect of alcohol on the [pb_glossary id=\"5999\"]excretory system[\/pb_glossary] \u2014 the system that removes wastes such as urine \u2014 is usually temporary. However, in people who drink excessively, alcohol can have serious, long-term effects on the excretory system. Heavy drinking on a regular basis can cause liver and kidney disease.\r\n\r\nAs you will learn in this chapter, the [pb_glossary id=\"2989\"]liver[\/pb_glossary] and [pb_glossary id=\"2988\"]kidneys[\/pb_glossary] are important organs of the excretory system, and impairment of the functioning of these organs can cause serious health consequences. At the end of the chapter, you will learn which hormone Talia was referring to. You will also learn some of the ways alcohol can affect the excretory system \u2014 both after the occasional drink, and in cases of excessive alcohol use and abuse.\r\n<div>\r\n<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">Chapter Overview: Excretory System<\/span><\/h1>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nIn this chapter, you will learn about the excretory system, which rids the body of toxic waste products and helps maintain homeostasis. Specifically, you will learn about:\r\n<ul>\r\n \t<li>The organs of the excretory system \u2014including the skin, liver, large intestine, lungs, and kidneys \u2014 that eliminate waste and excess water from the body.<\/li>\r\n \t<li>How wastes are eliminated through sweat, feces, urine, and exhaled gases.<\/li>\r\n \t<li>How toxic substances in the blood are broken down by the liver.<\/li>\r\n \t<li>The urinary system, which includes the kidneys, ureters, bladder, and urethra.<\/li>\r\n \t<li>The main function of the urinary system, which is to filter the blood and eliminate wastes, mineral ions, and excess water from the body in the form of urine.<\/li>\r\n \t<li>How the kidneys filter the blood, retain necessary substances, produce urine, and help maintain homeostasis (such as proper ion and water balance).<\/li>\r\n \t<li>How urine is stored, transported, and released from the body.<\/li>\r\n \t<li>Disorders of the urinary system, including bladder infections, kidney stones, polycystic kidney disease, urinary incontinence, and kidney damage caused by factors such as uncontrolled diabetes and high blood pressure.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox shaded\">\r\n\r\nAs you read the chapter, think about the following questions:\r\n<ol>\r\n \t<li>Which hormone do you think Talia was referring to? Remember that this hormone causes the urinary system to retain water and excrete less water out in urine.<\/li>\r\n \t<li>How and where does this hormone work?<\/li>\r\n \t<li>Long-term, excessive use of alcohol can affect the liver and kidneys. How do these two organs of excretion interact and work together?<\/li>\r\n<\/ol>\r\n<\/div>\r\n<h2>Attributions<\/h2>\r\n<strong>Figure 16.1.1<\/strong>\r\n\r\n<a href=\"https:\/\/flic.kr\/p\/6Pdgsh\" rel=\"cc:attributionURL\">Gotta Pee<\/a> [photo] by <a class=\"owner-name truncate\" title=\"Go to Jon-Eric Mels\u00e6ter's photostream\" href=\"https:\/\/www.flickr.com\/photos\/jonmelsa\/\" data-track=\"attributionNameClick\">Jon-Eric Mels\u00e6ter<\/a> on <a href=\"http:\/\/flickr.com\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" rel=\"license\">CC BY 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.0\/) license.\r\n\r\n<strong>Figure 16.1.2<\/strong>\r\n\r\n<a href=\"https:\/\/flic.kr\/p\/PB16Q\" rel=\"cc:attributionURL\">Bathroom line up<\/a> [photo] by <a class=\"owner-name truncate\" title=\"Go to Dorothy's photostream\" href=\"https:\/\/www.flickr.com\/photos\/dorothyhess-pictures\/\" data-track=\"attributionNameClick\">Dorothy<\/a> on <a href=\"http:\/\/flickr.com\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" rel=\"license\">CC BY 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.0\/) license.\r\n\r\n<\/div>","rendered":"<p>&nbsp;<\/p>\n<figure id=\"attachment_4697\" aria-describedby=\"caption-attachment-4697\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-4697\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/Gotta-Pee-by-Jon-Eric-Melsaeter-on-Flickr-e1606265012586-2.jpg\" alt=\"Signs for mens and women's washroom.\" width=\"400\" height=\"234\" \/><figcaption id=\"caption-attachment-4697\" class=\"wp-caption-text\"><em>Figure 16.1.1 Alcohol may increase your visits to the restroom. <\/em><\/figcaption><\/figure>\n<h1>Case\u00a0Study: Drink and Flush<\/h1>\n<p>\u201cWow, this line for the restroom is long!\u201d Shae says to Talia, anxiously bobbing from side to side to ease the pressure in her bladder. Talia nods and says, \u201cIt\u2019s always like this at parties. It\u2019s the alcohol.\u201d<\/p>\n<p>Shae and Talia are 21-year-old college students at a party. They \u2014 along with the other party guests \u2014 have been drinking alcoholic beverages over the course of the evening. As the night goes on, the line for the restroom has gotten longer and longer. You may have noticed this phenomenon if you have been to places where large numbers of people are drinking alcohol, like at the ballpark in Figure 16.1.2.<\/p>\n<figure id=\"attachment_4702\" aria-describedby=\"caption-attachment-4702\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-4702\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Bathroom-line-up-by-Dorothy-on-flickr-cc-by-2.jpg\" alt=\"16.1.2 Bathroom Line up\" width=\"400\" height=\"300\" \/><figcaption id=\"caption-attachment-4702\" class=\"wp-caption-text\"><em>Figure 16.1.2 A line stretching out of a restroom door at a ballpark.<\/em><\/figcaption><\/figure>\n<p>Shae says, \u201cI wonder why alcohol makes you have to pee?\u201d Talia says she learned about this in her Human Biology class. She tells Shae that alcohol inhibits a hormone that helps you retain water. Instead of your body retaining water, you urinate more out. This could lead to dehydration, so she suggests that after their trip to the restroom, they start drinking water, instead of alcohol.<\/p>\n<p>For people who drink occasionally or moderately, this effect of alcohol on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_5999\">excretory system<\/a> \u2014 the system that removes wastes such as urine \u2014 is usually temporary. However, in people who drink excessively, alcohol can have serious, long-term effects on the excretory system. Heavy drinking on a regular basis can cause liver and kidney disease.<\/p>\n<p>As you will learn in this chapter, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2989\">liver<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2988\">kidneys<\/a> are important organs of the excretory system, and impairment of the functioning of these organs can cause serious health consequences. At the end of the chapter, you will learn which hormone Talia was referring to. You will also learn some of the ways alcohol can affect the excretory system \u2014 both after the occasional drink, and in cases of excessive alcohol use and abuse.<\/p>\n<div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">Chapter Overview: Excretory System<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<p>In this chapter, you will learn about the excretory system, which rids the body of toxic waste products and helps maintain homeostasis. Specifically, you will learn about:<\/p>\n<ul>\n<li>The organs of the excretory system \u2014including the skin, liver, large intestine, lungs, and kidneys \u2014 that eliminate waste and excess water from the body.<\/li>\n<li>How wastes are eliminated through sweat, feces, urine, and exhaled gases.<\/li>\n<li>How toxic substances in the blood are broken down by the liver.<\/li>\n<li>The urinary system, which includes the kidneys, ureters, bladder, and urethra.<\/li>\n<li>The main function of the urinary system, which is to filter the blood and eliminate wastes, mineral ions, and excess water from the body in the form of urine.<\/li>\n<li>How the kidneys filter the blood, retain necessary substances, produce urine, and help maintain homeostasis (such as proper ion and water balance).<\/li>\n<li>How urine is stored, transported, and released from the body.<\/li>\n<li>Disorders of the urinary system, including bladder infections, kidney stones, polycystic kidney disease, urinary incontinence, and kidney damage caused by factors such as uncontrolled diabetes and high blood pressure.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"textbox shaded\">\n<p>As you read the chapter, think about the following questions:<\/p>\n<ol>\n<li>Which hormone do you think Talia was referring to? Remember that this hormone causes the urinary system to retain water and excrete less water out in urine.<\/li>\n<li>How and where does this hormone work?<\/li>\n<li>Long-term, excessive use of alcohol can affect the liver and kidneys. How do these two organs of excretion interact and work together?<\/li>\n<\/ol>\n<\/div>\n<h2>Attributions<\/h2>\n<p><strong>Figure 16.1.1<\/strong><\/p>\n<p><a href=\"https:\/\/flic.kr\/p\/6Pdgsh\" rel=\"cc:attributionURL\">Gotta Pee<\/a> [photo] by <a class=\"owner-name truncate\" title=\"Go to Jon-Eric Mels\u00e6ter's photostream\" href=\"https:\/\/www.flickr.com\/photos\/jonmelsa\/\" data-track=\"attributionNameClick\">Jon-Eric Mels\u00e6ter<\/a> on <a href=\"http:\/\/flickr.com\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" rel=\"license\">CC BY 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.0\/) license.<\/p>\n<p><strong>Figure 16.1.2<\/strong><\/p>\n<p><a href=\"https:\/\/flic.kr\/p\/PB16Q\" rel=\"cc:attributionURL\">Bathroom line up<\/a> [photo] by <a class=\"owner-name truncate\" title=\"Go to Dorothy's photostream\" href=\"https:\/\/www.flickr.com\/photos\/dorothyhess-pictures\/\" data-track=\"attributionNameClick\">Dorothy<\/a> on <a href=\"http:\/\/flickr.com\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" rel=\"license\">CC BY 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.0\/) license.<\/p>\n<\/div>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_5205_5999\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_5205_5999\"><div tabindex=\"-1\"><p>The body system responsible for the elimination of wastes produced by homeostasis. There are several parts of the body that are involved in this process, such as sweat glands, the liver, the lungs and the kidney system. ... From there, urine is expelled through the urethra and out of the body.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_5205_2989\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_5205_2989\"><div tabindex=\"-1\"><p>Created by CK-12 Foundation\/Adapted by Christine Miller<\/p>\n<figure id=\"attachment_1188\" aria-describedby=\"caption-attachment-1188\" style=\"width: 332px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1180\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/US_Marines_butterfly_stroke.jpg\" alt=\"13.3.1 Butterfly Stroke\" width=\"332\" height=\"500\"><figcaption id=\"caption-attachment-1188\" class=\"wp-caption-text\"><em>Figure 13.3.1 How long can you hold your breath?<\/em><\/figcaption><\/figure>\n<div>\n<h1>Doing the \u2018Fly<\/h1>\n<\/div>\n<p>The swimmer in the Figure 13.3.1 photo is doing the butterfly stroke, a swimming style that requires the swimmer to carefully control his breathing so it is coordinated with his swimming movements. Breathing is the process of moving air into and out of the lungs, which are the organs in which gas exchange takes place between the atmosphere and the body. Breathing is also called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4287\">ventilation<\/a>,<\/strong>\u00a0and it is one of two parts of the life-sustaining process of respiration. The other part\u00a0is\u00a0gas exchange. Before you can understand how breathing is controlled, you need to know how breathing occurs.<\/p>\n<div>\n<h1>How Breathing Occurs<\/h1>\n<\/div>\n<p>Breathing is a two-step process that includes drawing air into the lungs, or inhaling, and letting air out of the lungs, or exhaling. Both processes are illustrated in Figure 13.3.2.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_1188\" aria-describedby=\"caption-attachment-1188\" style=\"width: 632px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1182\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Inhale-Exhale-by-Siyavula-Education-on-flickr.jpg\" alt=\"13.3.2 Inhalation and Exhalation\" width=\"632\" height=\"465\"><figcaption id=\"caption-attachment-1188\" class=\"wp-caption-text\"><em>Figure 13.3.2 Breathing depends mainly on repeated contractions of the diaphragm.<\/em><\/figcaption><\/figure>\n<h2>Inhaling<\/h2>\n<p>Inhaling is an active process that results mainly from contraction of a muscle called the diaphragm, shown in Figure 13.3.2. The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4292\">diaphragm<\/a> <\/strong>is a large, dome-shaped muscle below the lungs that separates the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2925\">thoracic<\/a> (chest) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2475\">abdominal<\/a> cavities. When the diaphragm contracts it moves down causing the thoracic cavity to expand, and the contents of the abdomen\u00a0<span style=\"font-size: 1em\">to be pushe<\/span><span style=\"text-align: initial;font-size: 1em\">d downward. Other muscles \u2014 such as intercostal muscles between the ribs \u2014 also contribute to the process of <\/span><span style=\"text-align: initial;font-size: 1em\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4325\">inhalation<\/a><\/span><span style=\"text-align: initial;font-size: 1em\">, especially when inhalation is forced, as when taking a deep breath. These muscles help increase thoracic volume by expanding the ribs outward. The increase in thoracic volume creates a decrease in thoracic air pressure.\u00a0 With the chest expanded, there is lower air pressure inside the lungs than outside the body, so outside air flows into the lungs via the respiratory tract according the the pressure gradient (high pressure flows to lower pressure).<\/span><\/p>\n<h2>Exhaling<\/h2>\n<p>Exhaling involves the opposite series of events. The diaphragm relaxes, so it moves upward and decreases the volume of the thorax. Air pressure inside the lungs increases, so it is higher than the air pressure outside the lungs. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4326\">Exhalation<\/a>, unlike inhalation, is typically a passive process that occurs mainly due to the elasticity of the lungs. With the change in air pressure, the lungs contract to their pre-inflated size, forcing out the air they contain in the process. Air flows out of the lungs, similar to the way air rushes out of a balloon when it is released. If exhalation is forced, internal intercostal and abdominal muscles may help move the air out of the lungs.<\/p>\n<div>\n<h1>Control of Breathing<\/h1>\n<\/div>\n<p>Breathing is one of the few vital bodily functions that can be controlled consciously, as well as unconsciously. Think about using your breath to blow up a balloon. You take a long, deep breath, and then you exhale the air as forcibly as you can into the balloon. Both the inhalation and exhalation are consciously controlled.<\/p>\n<h2>Conscious Control of Breathing<\/h2>\n<p>You can control your breathing by holding your breath, slowing your breathing, or\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4327\">hyperventilating<\/a>,<\/strong> which is breathing more quickly and shallowly than necessary. You can also exhale or inhale more forcefully or deeply than usual. Conscious control of breathing is common in many activities besides blowing up balloons, including swimming, speech training, singing, playing many different musical instruments (Figure 13.3.3), and doing yoga, to name just a few.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_1188\" aria-describedby=\"caption-attachment-1188\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-4328\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Trumpet-by-morgan-petroski-ZCX1Nyok66c-unsplash-scaled-1.jpg\" alt=\"13.3.3 Conscious Control of Breathing\" width=\"400\" height=\"267\"><figcaption id=\"caption-attachment-1188\" class=\"wp-caption-text\"><em>Figure 13.3.3 Playing the trumpet is hard work. Exhaled air must be forced through the lips hard enough to create a vibrating column of air inside the instrument.<\/em><\/figcaption><\/figure>\n<p>There are limits on the conscious control of breathing. For example, it is not possible for a healthy person to voluntarily stop breathing indefinitely. Before long, there is an irrepressible urge to breathe. If you were able to stop breathing for a long enough time, you would lose consciousness. The same thing would happen if you were to hyperventilate for too long. Once you lose consciousness so you can no longer exert conscious control over your breathing, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3005\">involuntary<\/a> control of breathing takes over.<\/p>\n<h2>Unconscious Control of Breathing<\/h2>\n<p>Unconscious breathing is controlled by\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4329\">respiratory centers<\/a><\/strong> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3075\">medulla<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3076\">pons<\/a> of the brainstem (see Figure 13.3.4). The respiratory centers automatically and continuously regulate the rate of breathing based on the body\u2019s needs. These are determined mainly by blood acidity, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4330\">pH<\/a>. When you exercise, for example, carbon dioxide levels increase in the blood, because of increased cellular respiration by muscle cells. The carbon dioxide reacts with water in the blood to produce carbonic acid, making the blood more acidic, so pH falls. The drop in pH is detected by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3128\">chemoreceptor<span style=\"font-size: 1em\">s<\/span><span style=\"text-align: initial;font-size: 1em\"><\/a><\/span><span style=\"text-align: initial;font-size: 1em\">\u00a0in the medulla. Blood levels of oxygen and carbon dioxide, in addition to pH, are also detected by chemoreceptors in major arteries, which send the \u201cdata\u201d to the respiratory centers. The latter respond by sending\u00a0nerve impulses\u00a0to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4292\">diaphragm<\/a>, \u201ctelling\u201d it to contract more quickly so the rate of breathing speeds up. With faster breathing, more carbon dioxide is released into the air from the blood, and blood pH returns to the normal range.<\/span><\/p>\n<figure id=\"attachment_1188\" aria-describedby=\"caption-attachment-1188\" style=\"width: 521px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1187\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Respiratory_Centers_of_the_Brain.jpg\" alt=\"13.3.4 Nervous Control of Respiration\" width=\"521\" height=\"672\"><figcaption id=\"caption-attachment-1188\" class=\"wp-caption-text\"><em>Figure 13.3.4 Clusters of cells in the pons and medulla of the brain stem are the respiratory centers of the brain that have involuntary control over breathing.<\/em><\/figcaption><\/figure>\n<p>The opposite events occur when the level of carbon dioxide in the blood becomes too low and blood pH rises. This may occur with involuntary hyperventilation, which can happen in panic attacks, episodes of severe pain, asthma attacks, and many other situations. When you hyperventilate, you blow off a lot of carbon dioxide, leading to a drop in blood levels of carbon dioxide. The blood becomes more basic (alkaline), causing its pH to rise.<\/p>\n<div>\n<h1>Nasal vs. Mouth Breathing<\/h1>\n<\/div>\n<p>Nasal breathing is breathing through the nose rather than the mouth, and it is generally considered to be superior to mouth breathing. The hair-lined nasal passages do a better job of filtering particles out of the air before it moves deeper into the respiratory tract. The nasal passages are also better at warming and moistening the air, so nasal breathing is especially advantageous in the winter when the air is cold and dry. In addition, the smaller diameter of the nasal passages creates greater pressure in the lungs during exhalation. This slows the emptying of the lungs, giving them more time to extract oxygen from the air.<\/p>\n<div>\n<h1>Feature: Myth vs. Reality<\/h1>\n<\/div>\n<p><strong>Drowning<\/strong> is defined as respiratory impairment from being in or under a liquid. It is further classified according to its outcome into: death, ongoing health problems, or no ongoing health problems (full recovery). Four hundred Canadians die annually from drowning, and drowning is one of the leading causes of death in children under the age of five. There are some potentially dangerous myths about drowning, and knowing what they are might save your life or the life of a loved one, especially a child.<\/p>\n<table class=\"grid\" style=\"border-collapse: collapse;width: 100%\" border=\"0\">\n<tbody>\n<tr>\n<th scope=\"col\"><span style=\"color: #ff0000\">Myth<\/span><\/th>\n<th scope=\"col\"><span style=\"color: #008000\">Reality<\/span><\/th>\n<\/tr>\n<tr>\n<td><em>\"People drown when they aspirate water into their lungs.\"<\/em><\/td>\n<td>Generally, in the early stages of drowning, very little\u00a0water\u00a0enters the lungs. A small amount of water entering the trachea causes a muscular spasm in the larynx that seals the airway and prevents the passage of water into the lungs. This spasm is likely to last until unconsciousness occurs.<\/td>\n<\/tr>\n<tr>\n<td><em>\"You can tell when someone is drowning because they will shout for help and wave their arms to attract attention.\"<\/em><\/td>\n<td>The muscular spasm that seals the airway prevents the passage of air, as well as water, so a person who is drowning is unable to shout or call for help. In addition, instinctive reactions that occur in the final minute or so before a drowning person sinks under the water may look similar to calm, safe behavior. The head is likely to be low in the water, tilted back, with the mouth open. The person may have uncontrolled movements of the arms and legs, but they are unlikely to be visible above the water.<\/td>\n<\/tr>\n<tr>\n<td><em>\"It is too late to save a person who is unconscious in the water.\"<\/em><\/td>\n<td>An unconscious person rescued with an airway still sealed from the muscular spasm of the larynx stands a good chance of full recovery if they start receiving CPR within minutes. Without water in the lungs, CPR is much more effective. Even if cardiac arrest has occurred so the\u00a0heart\u00a0is no longer beating, there is still a chance of recovery.\u00a0The longer the brain goes without oxygen, however, the more likely brain\u00a0cells\u00a0are to\u00a0die. Brain death is likely after about six minutes without oxygen, except in exceptional circumstances, such as young people drowning in very cold water. There are examples of children surviving, apparently without lasting ill effects, for as long as an hour in cold water.\u00a0Rescuers retrieving a child from cold water should attempt resuscitation even after a protracted period of immersion.<\/td>\n<\/tr>\n<tr>\n<td><em>\"If someone is drowning, you should start administering CPR immediately, even before you try to get the person out of the water.\"<\/em><\/td>\n<td>Removing a drowning person from the water is the first priority, because CPR is ineffective in the water. The goal should be to bring the person to stable ground as quickly as possible and\u00a0then\u00a0to start CPR.<\/td>\n<\/tr>\n<tr>\n<td><em>\"You are unlikely to drown unless you are in water over your head.\"<\/em><\/td>\n<td>Depending on circumstances, people have drowned in as little as 30 mm (about 1 \u00bd in.) of water. Inebriated people or those under the influence of drugs, for example, have been known to have drowned in puddles. Hundreds of children have drowned in the water in toilets, bathtubs, basins, showers, pails, and buckets (see Figure 13.3.5).<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<figure id=\"attachment_1188\" aria-describedby=\"caption-attachment-1188\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1188\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Lily-Ava-in-the-Kiddie-Pool-by-mob-mob-on-flickr.jpg\" alt=\"13.3.5 Supervision of Children Near Water\" width=\"400\" height=\"300\"><figcaption id=\"caption-attachment-1188\" class=\"wp-caption-text\"><em>Figure 13.3.5 Young children should never be left unattended around sources of water that pose a risk of drowning, including water in toilets, bathtubs, and buckets. Here, there are clearly two adults supervising within arm's reach.<\/em><\/figcaption><\/figure>\n<div>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">13.3 Summary<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Breathing, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4287\">ventilation<\/a>, is the two-step process of drawing air into the lungs (inhaling) and letting air out of the lungs (exhaling). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4325\">Inhalation<\/a> is an active process that results mainly from contraction of a muscle called the diaphragm. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4326\">Exhalation<\/a> is typically a passive process that occurs mainly due to the elasticity of the lungs when the diaphragm relaxes.<\/li>\n<li>Breathing is one of the few vital bodily functions that can be controlled consciously, as well as unconsciously. Conscious control of breathing is common in many activities, including swimming and singing. There are limits on the conscious control of breathing, however. If you try to hold your breath, for example, you will soon have an irrepressible urge to breathe.<\/li>\n<li>Unconscious breathing is controlled by respiratory centers in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3075\">medulla<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3076\">pons<\/a> of the brainstem. They respond to variations in blood <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4330\">pH<\/a> by either increasing or decreasing the rate of breathing as needed to return the pH level to the normal range.<\/li>\n<li>Nasal breathing is generally considered to be superior to mouth breathing because it does a better job of filtering, warming, and moistening incoming air. It also results in slower emptying of the lungs, which allows more oxygen to be extracted from the air.<\/li>\n<li>Drowning is a major cause of death in Canada, in particular in children under the age of five.\u00a0 It is important to supervise small children when they are playing in, around, or with water.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\"><span style=\"color: #ffffff\">13.3 Review Questions<\/span><\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ol>\n<li>Define breathing.<\/li>\n<li>\n<div id=\"h5p-240\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-240\" class=\"h5p-iframe\" data-content-id=\"240\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13.3 Quiz\"><\/iframe><\/div>\n<\/div>\n<\/li>\n<li>Give examples of activities in which breathing is consciously controlled.<\/li>\n<li>Explain how unconscious breathing is controlled.<\/li>\n<li>Young children sometimes threaten to hold their breath until they get something they want. Why is this an idle threat?<\/li>\n<li>Why is nasal breathing generally considered superior to mouth breathing?<\/li>\n<li>Give one example of a situation that would cause blood pH to rise excessively. Explain why this occurs.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">13.3 Explore More<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<p>https:\/\/www.youtube.com\/watch?v=Kl4cU9sG_08<\/p>\n<p style=\"text-align: center\">How breathing works - Nirvair Kaur, TED-Ed, 2012.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=yDtKBXOEsoM<\/p>\n<p style=\"text-align: center\">How do ventilators work? - Alex Gendler, TED-Ed, 2020.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=XFnGhrC_3Gs&amp;feature=emb_logo<\/p>\n<p style=\"text-align: center\">How I held my breath for 17 minutes | David Blaine, TED, 2010.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=Vca6DyFqt4c&amp;feature=emb_logo<\/p>\n<p style=\"text-align: center\">The Ultimate Relaxation Technique: How To Practice Diaphragmatic Breathing For Beginners, Kai Simon, 2015.<\/p>\n<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<\/div>\n<h2>Attributions<\/h2>\n<p><strong>Figure 13.3.1<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:US_Marines_butterfly_stroke.jpg\" rel=\"cc:attributionURL\">US_Marines_butterfly_stroke<\/a> by Cpl. Jasper Schwartz from <a href=\"https:\/\/www.marines.mil\/Photos\/\">U.S. Marine Corps<\/a> on Wikimedia Commons is in the <a class=\"extiw\" title=\"w:public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/public_domain\">public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/p>\n<p><strong>Figure 13.3.2<\/strong><\/p>\n<p><a href=\"https:\/\/www.flickr.com\/photos\/121935927@N06\/13579206934\" rel=\"cc:attributionURL\">Inhale Exhale\/Breathing cycle<\/a> by\u00a0<a href=\"https:\/\/www.flickr.com\/photos\/121935927@N06\/\" rel=\"dc:creator\">Siyavula Education<\/a> on <a href=\"http:\/\/flickr.com\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" rel=\"license\">CC BY 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.0\/) license.<\/p>\n<p><strong>Figure 13.3.3<\/strong><\/p>\n<p><a href=\"https:\/\/unsplash.com\/photos\/ZCX1Nyok66c\" rel=\"cc:attributionURL\">Trumpet\/ Frenchmen Street<\/a> [photo] by <a href=\"https:\/\/unsplash.com\/@morgpetphoto\">Morgan Petroski<\/a> on <a href=\"http:\/\/unsplash.com\">Unsplash<\/a> is used under the <a href=\"https:\/\/unsplash.com\/license\">Unsplash License<\/a> (https:\/\/unsplash.com\/license).<\/p>\n<p><strong>Figure 13.3.4<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:2327_Respiratory_Centers_of_the_Brain.jpg\" rel=\"cc:attributionURL\">Respiratory_Centers_of_the_Brain<\/a>\u00a0by <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/22-3-the-process-of-breathing\">OpenStax College<\/a> on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\" rel=\"license\">CC BY 3.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/3.0) license.<\/p>\n<p><strong>Figure 13.3.5<\/strong><\/p>\n<p><a href=\"https:\/\/www.flickr.com\/photos\/biblicone\/3824666787\/in\/photolist-6PYqbP-2rx2G4-k1BRwh-k1yTf4-k1AWPJ-k1ATvQ-k1AtQH-k1Ba4y-k1Aq6Z-k1zokP-k1BJEb-k1BDRd-k1AKWm-k1AkVV-k1BVF9-34B2Wq-9R7dYz-8LpXzH-db1AzK-88hqku-cuih1d-8dDyrC-552bDq-8Lt271-ah3o62-ah3mVT-ah3vvn-ah3rwZ-52JEwW-6WBC6J-iN49k-6WBxTQ-fMsxQ-6WBBP3-6Wxxzp-6WxBUr-nHMBGd-6WBwR5-ntkqz2-afw3yG-2xYzte-4EwN9E-5i7YUV-5i7YQi-5rNPvg-cpVzUU-Ytmnt-4NHgLz-4TeKZr-pS5BjJ\" rel=\"cc:attributionURL\">Lily &amp; Ava in the Kiddie Pool<\/a> by\u00a0<a href=\"https:\/\/www.flickr.com\/photos\/biblicone\/\" rel=\"dc:creator\">mob mob<\/a> on <a href=\"http:\/\/flickr.com\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\" rel=\"license\">CC BY-NC 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/) license.<\/p>\n<h2>References<\/h2>\n<p class=\"hanging-indent\">Betts, J. G., Young, K.A., Wise, J.A., Johnson, E., Poe, B., Kruse, D.H., Korol, O., Johnson, J.E., Womble, M., DeSaix, P. (2013, June 19). Figure 22.20 Respiratory centers of the brain [digital image].\u00a0 In <em>Anatomy and Physiology<\/em> (Section 22.3). OpenStax. https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/22-3-the-process-of-breathing<\/p>\n<p class=\"hanging-indent\">Kai Simon. (2015, January 11). The ultimate relaxation technique: How to practice diaphragmatic breathing for beginners. YouTube. https:\/\/www.youtube.com\/watch?v=Vca6DyFqt4c&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED. (2010, January 19). How I held my breath for 17 minutes | David Blaine. YouTube. https:\/\/www.youtube.com\/watch?v=XFnGhrC_3Gs&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED-Ed. (2012, October 4). How breathing works - Nirvair Kaur. YouTube. https:\/\/www.youtube.com\/watch?v=Kl4cU9sG_08&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED-Ed. (2020, May 21). How do ventilators work? - Alex Gendler. YouTube. https:\/\/www.youtube.com\/watch?v=yDtKBXOEsoM&amp;feature=youtu.be<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_5205_2988\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_5205_2988\"><div tabindex=\"-1\"><p>Created by CK-12 Foundation\/Adapted by Christine Miller<\/p>\n<figure id=\"attachment_1172\" aria-describedby=\"caption-attachment-1172\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-4285\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/Exhale-by-pavel-lozovikov-HYovA7yPPvI-unsplash-scaled-1.jpg\" alt=\"13.2.1 Exhale\" width=\"400\" height=\"267\"><figcaption id=\"caption-attachment-1172\" class=\"wp-caption-text\"><em>Figure 13.2.1 Every breath you take...\u00a0<\/em><\/figcaption><\/figure>\n<div>\n<h1>Seeing Your Breath<\/h1>\n<\/div>\n<p>Why can you \u201csee your breath\u201d on a cold day? The air you exhale through your nose and mouth is warm like the inside of your body. Exhaled air also contains a lot of\u00a0water\u00a0vapor, because it passes over moist surfaces from the lungs to the nose or mouth. The water vapor in your breath cools suddenly when it reaches the much colder outside air. This causes the water vapor to condense into a\u00a0fog\u00a0of tiny droplets of\u00a0liquid\u00a0water. You release water vapor and other gases from your body through the process of respiration.<\/p>\n<div>\n<h1>What is Respiration?<\/h1>\n<\/div>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4286\">Respiration<\/a><\/strong>\u00a0is the life-sustaining process in which gases are exchanged between the body and the outside atmosphere. Specifically, oxygen moves from the outside air into the body; and\u00a0water\u00a0vapor, carbon dioxide, and other waste gases move from inside the body to the outside air. Respiration is carried out mainly by the\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2912\">respiratory system<\/a><\/strong><strong>.<\/strong>\u00a0It is important to note that respiration by the\u00a0respiratory system\u00a0is not the same process as\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2305\">cellular respiration<\/a>\u00a0\u2014which occurs inside\u00a0cells\u00a0\u2014 although the two processes are closely connected. Cellular respiration is the metabolic process in which cells obtain\u00a0energy, usually by \u201cburning\u201d glucose in the presence of oxygen. When cellular respiration is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_1796\">aerobic<\/a>, it uses oxygen and releases carbon dioxide as a waste product. Respiration by the respiratory system supplies the oxygen needed by cells for aerobic cellular respiration, and removes the carbon dioxide produced by cells during cellular respiration.<\/p>\n<p>Respiration by the\u00a0respiratory system\u00a0actually involves two subsidiary processes. One process is\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4287\">ventilation<\/a><\/strong>, or\u00a0breathing.\u00a0Ventilation\u00a0is the physical process of conducting air to and from the lungs. The other process is\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4288\">gas exchange<\/a><\/strong>. This is the biochemical process in which oxygen diffuses out of the air and into the\u00a0blood, while carbon dioxide and other waste gases diffuse out of the blood and into the air. All of the organs of the respiratory system are involved in\u00a0breathing, but only the lungs are involved in\u00a0gas exchange.<\/p>\n<div>\n<h1>Respiratory Organs<\/h1>\n<\/div>\n<p>The organs of the respiratory system form a continuous system of passages, called the\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4289\">respiratory tract<\/a>,<\/strong> through which air flows into and out of the body. The respiratory tract has two major divisions: the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4290\">upper respiratory tract<\/a> and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4291\">lower respiratory tract<\/a>. The organs in each division are shown in Figure 13.2.2. In addition to these organs, certain muscles of the thorax (body cavity that fills the chest) are also involved in respiration by enabling breathing. Most important is a large muscle called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4292\">diaphragm<\/a>, which lies below the lungs and separates the thorax from the abdomen. Smaller muscles between the ribs also play a role in breathing.<\/p>\n<figure id=\"attachment_1172\" aria-describedby=\"caption-attachment-1172\" style=\"width: 466px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1152\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Illu_conducting_passages.svg_.png\" alt=\"13.2.2 Respiratory Tract\" width=\"466\" height=\"600\"><figcaption id=\"caption-attachment-1172\" class=\"wp-caption-text\"><em>Figure 13.2.2 During breathing, inhaled air enters the body through the nose and passes through the respiratory tract to the lungs. Exhaled air travels from the lungs in the opposite direction.<\/em><\/figcaption><\/figure>\n<h2>Upper Respiratory Tract<\/h2>\n<p>All of the organs and other structures of the upper respiratory tract are involved in\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4294\">conduction<\/a><\/strong>, or the movement of air into and out of the body. Upper respiratory tract organs provide a route for air to move between the outside atmosphere and the lungs. They also clean, humidify, and warm the incoming air. No gas exchange occurs in these organs.<\/p>\n<h3>Nasal Cavity<\/h3>\n<p>The\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4295\">nasal cavity<\/a><\/strong>\u00a0is a large, air-filled space in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3957\">skull<\/a> above and behind the nose in the middle of the face. It is a continuation of the two nostrils. As inhaled air flows through the nasal cavity, it is warmed and humidified by blood vessels very close to the surface of this epithelial tissue . Hairs in the nose and mucous produced by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3538\">mucous membrane<span style=\"font-size: 1em\">s<\/span><span style=\"text-align: initial;font-size: 1em\"><\/a><\/span><span style=\"text-align: initial;font-size: 1em\">\u00a0help trap larger foreign particles in the air before they go deeper into the respiratory tract. In addition to its respiratory functions, the nasal cavity also contains <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3128\">chemoreceptor<\/span><span style=\"text-align: initial;font-size: 1em\">s<\/span><span style=\"text-align: initial;font-size: 1em\"><\/a><\/span><span style=\"text-align: initial;font-size: 1em\">\u00a0 needed for sense of smell, and contribution to the sense of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_3157\">taste<\/a>.<\/span><\/p>\n<h3>Pharynx<\/h3>\n<p>The\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4296\">pharynx<\/a><\/strong>\u00a0is a tube-like structure that connects the nasal cavity and the back of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4297\">mouth<\/a> to other structures lower in the throat, including the larynx. The pharynx has dual functions \u2014 both air and food (or other swallowed substances) pass through it, so it is part of both the respiratory and the digestive systems. Air passes from the nasal cavity through the pharynx to the larynx (as well as in the opposite direction). Food passes from the mouth through the pharynx to the esophagus.<\/p>\n<h3>Larynx<\/h3>\n<p style=\"text-align: left\">The\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4298\">larynx<\/a><\/strong> connects the pharynx and trachea, and helps to conduct air through the respiratory tract. The larynx is also called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4299\">voice box<\/a>, because it contains the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4320\">vocal cords<\/a>, which vibrate when air flows over them, thereby producing sound. You can see the vocal cords in the larynx in Figures 13.2.3 and 13.2.4. Certain muscles in the larynx move the vocal cords apart to allow breathing. Other muscles in the larynx move the vocal cords together to allow the production of vocal sounds. The latter muscles also control the pitch of sounds and help control their volume.<\/p>\n<table class=\" aligncenter\" style=\"border-collapse: collapse;width: 95.0523%;height: 10px\" border=\"0\">\n<tbody>\n<tr style=\"height: 50px\">\n<td style=\"width: 50%;height: 10px\">\n<figure id=\"attachment_1155\" aria-describedby=\"caption-attachment-1155\" style=\"width: 392px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1155\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/larynx.jpg\" alt=\"13.2.3 Larynx external view\" width=\"392\" height=\"314\"><figcaption id=\"caption-attachment-1155\" class=\"wp-caption-text\"><em>Figure 13.2.3 The larynx as viewed from externally.<\/em><\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 53.5346%;height: 10px;text-align: left\">&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><img class=\"wp-image-1157\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Larynx-top-view-nci-vol-4370-72.jpg\" alt=\"13.2.4 Larynx top view\" width=\"330\" height=\"297\"><\/p>\n<p><em>Figure 13.2.4 The larynx as viewed from the top.<\/em><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: left\">A very important function of the larynx is protecting the trachea from aspirated food. When swallowing occurs, the backward motion of the tongue forces a flap called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4302\">epiglottis<\/a> to close over the entrance to the larynx. (You can see the epiglottis in both Figure 13.2.3 and 13.2.4.) This prevents swallowed material from entering the larynx and moving deeper into the respiratory tract. If swallowed material does start to enter the larynx, it irritates the larynx and stimulates a strong cough reflex. This generally expels the material out of the larynx, and into the throat.<\/p>\n<p>&nbsp;<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=BsyB88mq5rQ<\/p>\n<p style=\"text-align: center\">Larynx Model - Respiratory System, Dr. Lotz, 2018.<\/p>\n<h2>Lower Respiratory Tract<\/h2>\n<figure id=\"attachment_1172\" aria-describedby=\"caption-attachment-1172\" style=\"width: 294px\" class=\"wp-caption alignleft\"><img class=\"wp-image-1159\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/2000px-Lungs_diagram_detailed.svg_.png\" alt=\"13.2.5 Branching in the lower respiratory tract\" width=\"294\" height=\"375\"><figcaption id=\"caption-attachment-1172\" class=\"wp-caption-text\"><em>Figure 13.2.5 This diagram illustrates the tree-like branching of the passages of the lower respiratory tract within the lungs.<\/em><\/figcaption><\/figure>\n<p>The trachea and other passages of the lower respiratory tract conduct air between the upper respiratory tract and the lungs. These passages form an inverted tree-like shape (Figure 13.2.5), with repeated branching as they move deeper into the lungs. All told, there are an astonishing 2,414 kilometres (1,500 miles) of airways conducting air through the human respiratory tract! It is only in the lungs, however, that gas exchange occurs between the air and the bloodstream.<\/p>\n<h3>Trachea<\/h3>\n<p>The\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4304\">trachea<\/a>,<\/strong> or windpipe, is the widest passageway in the respiratory tract. It is about 2.5 cm wide and 10-15 cm long (approximately 1 inch wide and 4\u20136 inches long). It is formed by rings of cartilage, which make it relatively strong and resilient. The trachea connects the larynx to the lungs for the passage of air through the respiratory tract. The trachea branches at the bottom to form two bronchial tubes.<\/p>\n<h3>Bronchi and Bronchioles<\/h3>\n<p>There are two main bronchial tubes, or\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4309\">bronchi<\/a> (singular, bronchus)<\/strong>, called the right and left bronchi. The bronchi carry air between the trachea and lungs. Each bronchus branches into smaller, secondary bronchi; and secondary bronchi branch into still smaller tertiary bronchi. The smallest bronchi branch into very small tubules called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4310\">bronchiole<\/a>s. The tiniest bronchioles end in alveolar ducts, which terminate in clusters of minuscule\u00a0air sacs, called\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4311\"><strong>alveoli<\/strong>\u00a0<\/a>(singular, alveolus), in the lungs.<\/p>\n<h3>Lungs<\/h3>\n<p>The\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2990\">lungs<\/a><\/strong>\u00a0are the largest organs of the respiratory tract. They are suspended within the pleural cavity of the thorax. The lungs are surrounded by two thin membranes called\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4312\">pleura<\/a><\/strong>, which secrete fluid that allows the lungs to move freely within the pleural cavity. This is necessary so the lungs can expand and contract during breathing. In Figure 13.2.6, you can see that each of the two lungs is divided into sections. These are called lobes, and they are separated from each other by connective tissues. The right lung is larger and contains three lobes. The left lung is smaller and contains only two lobes. The smaller left lung allows room for the heart, which is just left of the center of the chest.<\/p>\n<figure id=\"attachment_1172\" aria-describedby=\"caption-attachment-1172\" style=\"width: 543px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1164\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Gross_Anatomy_of_the_Lungs.jpg\" alt=\"13.2.6 Anatomy of the Lung\" width=\"543\" height=\"373\"><figcaption id=\"caption-attachment-1172\" class=\"wp-caption-text\"><em>Figure 13.2.6 The lungs are separated into the right and left lung.<\/em><\/figcaption><\/figure>\n<div>\n<p>As mentioned previously, the bronchi terminate in bronchioles which feed air into alveoli, tiny sacs of simple squamous epithelial tissue which make up the bulk of the lung.\u00a0\u00a0The cross-section of lung tissue in the diagram below (Figure 13.2.7) shows the alveoli, in which gas exchange takes place with the capillary network that surrounds them.<\/p>\n<table class=\" aligncenter\" style=\"border-collapse: collapse;width: 49.2386%;height: 420px\" border=\"0\">\n<tbody>\n<tr>\n<td style=\"width: 100%\">\n<figure id=\"attachment_1166\" aria-describedby=\"caption-attachment-1166\" style=\"width: 515px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1166\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Alveoli-Structure.jpg\" alt=\"13.2.7 Alveoli Structure\" width=\"515\" height=\"343\"><figcaption id=\"caption-attachment-1166\" class=\"wp-caption-text\"><em>Figure 13.2.7 Alveoli make up the bulk of the lung and form millions of grape-like clusters of air sacs for the purpose of exchanging gases with capillaries of the cardiovascular system.<\/em><\/figcaption><\/figure>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 100%\">\n<figure id=\"attachment_1168\" aria-describedby=\"caption-attachment-1168\" style=\"width: 674px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-1168\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/annotated_diagram_of_an_alveolus.svg_.png\" alt=\"13.2.8 Alveolus\" width=\"674\" height=\"506\"><figcaption id=\"caption-attachment-1168\" class=\"wp-caption-text\"><em>Figure 13.2.8 An alveolus in which gas exchange takes place with the capillary network that surrounds it. Surfactant is a liquid that covers the inside of the alveoli and prevents them from collapsing and sticking together when air empties out of them during exhalation.<\/em><\/figcaption><\/figure>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: center\">\n<\/div>\n<p>Lung tissue consists mainly of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4311\">alveoli<\/a> (see Figures 13.2.7 and 13.2.8). These tiny air sacs are the functional units of the lungs where gas exchange takes place. The two lungs may contain as many as 700 million alveoli, providing a huge total surface area for gas exchange to take place. In fact, alveoli in the two lungs provide as much surface area as half a tennis court! Each time you breathe in, the alveoli fill with air, making the lungs expand. Oxygen in the air inside the alveoli is absorbed by the blood via diffusion in the mesh-like network of tiny capillaries that surrounds each alveolus. The blood in these capillaries also releases carbon dioxide (also by diffusion) into the air inside the alveoli. Each time you breathe out, air leaves the alveoli and rushes into the outside atmosphere, carrying waste gases with it.<\/p>\n<p>The lungs receive blood from two major sources. They receive deoxygenated blood from the right side of the heart. This blood absorbs oxygen in the lungs and carries it back to the left side heart to be pumped to cells throughout the body. The lungs also receive oxygenated blood from the heart that provides oxygen to the cells of the lungs for cellular respiration.<\/p>\n<div>\n<h1>Protecting the Respiratory System<\/h1>\n<\/div>\n<p>You may be able to survive for weeks without food and for days without\u00a0water, but you can survive without oxygen for only a matter of minutes \u2014 except under exceptional circumstances \u2014 so protecting the respiratory system is vital. Ensuring that\u00a0a patient has an open airway is the first step in treating many medical emergencies. Fortunately, the respiratory system is well protected by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2142\">ribcage<\/a> of the\u00a0skeletal system.\u00a0The extensive surface area of the respiratory system, however, is directly exposed to the outside world and all its potential dangers in inhaled air.\u00a0It\u00a0should come as no surprise that the respiratory system has a variety of ways to protect itself from harmful substances, such as dust and pathogens in the air.<\/p>\n<p>The main way the respiratory system protects itself is called the\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4318\">mucociliary escalator<\/a><\/strong>. From the nose through the bronchi, the respiratory tract is covered in epithelium that contains mucus-secreting goblet\u00a0cells. The mucus traps particles and pathogens in the incoming air. The epithelium of the respiratory tract is also covered with tiny cell projections called\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_1597\">cilia<\/a><\/strong> (singular, cilium), as shown in the animation. The cilia constantly move in a sweeping motion upward toward the throat, moving the mucus and trapped particles and pathogens away from the lungs and toward the outside of the body. The upward sweeping motion of cilia lining the respiratory tract helps keep it free from dust, pathogens, and other harmful substances.<\/p>\n<p>Watch \"Mucociliary clearance\" by I-Hsun Wu to learn more:<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=HMB6flEaZwI<\/p>\n<p style=\"text-align: center\">Mucociliary clearance, I-Hsun Wu, <span style=\"font-size: 1em\">2015.<\/span><\/p>\n<div id=\"flex\" class=\"style-scope ytd-video-primary-info-renderer\"><\/div>\n<div id=\"menu-container\" class=\"style-scope ytd-video-primary-info-renderer\">\n<div id=\"menu\" class=\"style-scope ytd-video-primary-info-renderer\"><\/div>\n<div id=\"container\" class=\"style-scope ytd-sentiment-bar-renderer\"><span style=\"font-size: 1em;text-align: initial\">What happens to the material that moves up the mucociliary escalator to the throat? It is generally removed from the respiratory tract by clearing the throat or coughing. Coughing is a largely involuntary response of the respiratory system that occurs when nerves lining the airways are irritated. The response causes air to be expelled forcefully from the trachea, helping to remove mucus and any debris it contains (called phlegm) from the upper respiratory tract to the mouth. The phlegm may be spit out (expectorated), or it may be swallowed and destroyed by stomach acids.<\/span><\/div>\n<div><\/div>\n<\/div>\n<div><\/div>\n<figure id=\"attachment_1172\" aria-describedby=\"caption-attachment-1172\" style=\"width: 385px\" class=\"wp-caption alignleft\"><img class=\"wp-image-1172\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Sneeze.jpg\" alt=\"13.2.9 Sneeze\" width=\"385\" height=\"258\"><figcaption id=\"caption-attachment-1172\" class=\"wp-caption-text\"><em>Figure 13.2.9 Sneezing results in tiny particles from the mouth being forcefully ejected into the air.<\/em><\/figcaption><\/figure>\n<p>Sneezing is a similar involuntary response that occurs when nerves lining the nasal passage are irritated. It results in forceful expulsion of air from the mouth, which sprays millions of tiny droplets of mucus and other debris out of the mouth and into the air, as shown in Figure 13.2.9. This explains why it is so important to sneeze into a tissue (rather than the air) if we are to prevent the transmission of respiratory pathogens.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><span style=\"font-size: 1.602em;font-weight: bold\">How the Respiratory System Works with Other Organ Systems<\/span><\/p>\n<p>The amount of oxygen and carbon dioxide in the blood must be maintained within a limited range for survival of the organism. Cells cannot survive for long without oxygen, and if there is too much carbon dioxide in the blood, the blood becomes dangerously <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2258\">acidic<\/a> (pH is too low). Conversely, if there is too little carbon dioxide in the blood, the blood becomes too basic (pH is too high). The respiratory system works hand-in-hand with the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2908\">nervous<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2571\">cardiovascular<\/a> systems to maintain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2350\">homeostasis<\/a> in blood gases and pH.<\/p>\n<p>It is the level of carbon dioxide \u2014 rather than the level of oxygen \u2014 that is most closely monitored to maintain blood\u00a0gas\u00a0and\u00a0pH\u00a0homeostasis. The level of carbon dioxide in the blood is detected by cells in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_2554\">brain<\/a>, which\u00a0speed\u00a0up or slow down the rate of breathing through the autonomic\u00a0nervous system\u00a0as needed to bring the carbon dioxide level within the normal range. Faster breathing lowers the carbon dioxide level (and raises the oxygen level and pH), while slower breathing has the opposite effects. In this way, the levels of carbon dioxide, oxygen, and pH are maintained within normal limits.<\/p>\n<p>The respiratory system also works closely with the cardiovascular system to maintain homeostasis. The respiratory system exchanges gases with the outside air, but it needs the cardiovascular system to carry them to and from body cells. Oxygen is absorbed by the blood in the lungs and then transported through a vast network of blood vessels to cells throughout the body, where it is needed for aerobic cellular respiration. The same system absorbs carbon dioxide from cells and carries it to the respiratory system for removal from the body.<\/p>\n<div>\n<h1>Feature: My\u00a0Human Body<\/h1>\n<\/div>\n<p>Choking due to a foreign object becoming lodged in the airway results in nearly 5 thousand deaths in Canada each year. In addition, choking accounts for almost 40% of unintentional injuries in infants under the age of one.\u00a0 For the sake of your own human body, as well as those of loved ones, you should be aware of choking risks, signs, and treatments.<\/p>\n<p>Choking is the mechanical obstruction of the flow of air from the atmosphere into the lungs. It prevents breathing, and may be partial or complete. Partial choking allows some \u2014 though inadequate \u2014 air flow into the lungs. Prolonged or complete choking results in asphyxia, or suffocation, which is potentially fatal.<\/p>\n<p>Obstruction of the airway typically occurs in the pharynx or trachea. Young children are more prone to choking than are older people, in part because they often put small objects in their mouth and do not understand the risk of choking that they pose. Young children may choke on small toys or parts of toys, or on household objects, in addition to food. Foods that are round (hotdogs, carrots, grapes) or can adapt their shape to that of the pharynx (bananas, marshmallows), are especially dangerous, and may cause choking in adults, as well as children.<\/p>\n<p>How can you tell if a loved one is choking? The person cannot speak or cry out, or has great difficulty doing so. Breathing, if possible, is laboured, producing gasping or wheezing. The person may desperately clutch at his or her throat or mouth. If breathing is not soon restored, the person\u2019s face will start to turn blue from lack of oxygen. This will be followed by unconsciousness, brain damage, and possibly death if oxygen deprivation continues beyond a few minutes.<\/p>\n<p>If an infant is choking, turning the baby upside down and slapping him on the back may dislodge the obstructing object. To help an older person who is choking, first encourage the person to cough. Give them a few hard back slaps to help force the lodged object out of the airway. If these steps fail, perform the Heimlich maneuver on the person. See the series of\u00a0 videos below, from ProCPR, which demonstrate several ways to help someone who is choking based on age and consciousness.<\/p>\n<p>&nbsp;<\/p>\n<div>\n<p>https:\/\/www.youtube.com\/watch?v=XOTbjDGZ7wg&amp;t=46s<\/p>\n<p style=\"text-align: center\">Conscious Adult Choking, ProCPR, 2016.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=5kmsKNvKAvU<\/p>\n<p style=\"text-align: center\">Unconscious Adult Choking, ProCPR, 2011.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=ZjmbD7aIaf0<\/p>\n<p style=\"text-align: center\">Conscious Child Choking, ProCPR, 2009.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=Sba0T2XGIn4<\/p>\n<p style=\"text-align: center\">Unconscious Child Choking, ProCPR, 2009.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=axqIju9CLKA<\/p>\n<p style=\"text-align: center\">Conscious Infant Choking, ProCPR, 2011.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=_K7Dwy6b2wQ<\/p>\n<p style=\"text-align: center\">Unconscious Infant Choking, ProCPR, 2011.<\/p>\n<\/div>\n<div>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">13.2 Summary<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4286\">Respiration<\/a> is the process in which oxygen moves from the outside air into the body, and in which carbon dioxide and other waste gases move from inside the body into the outside air. It involves two subsidiary processes: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4287\">ventilation<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4288\">gas exchange<\/a>. Respiration is carried out mainly by the respiratory system.<\/li>\n<li>The organs of the respiratory system form a continuous system of passages, called the respiratory tract. It has two major divisions: the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4290\">upper respiratory tract<\/a> and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4291\">lower respiratory tract<\/a>.<\/li>\n<li>The upper respiratory tract includes the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4295\">nasal cavity<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4296\">pharynx<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4298\">larynx<\/a>. All of these organs are involved in conduction, or the movement of air into and out of the body. Incoming air is also cleaned, humidified, and warmed as it passes through the upper respiratory tract. The larynx is called the voice box, because it contains the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4320\">vocal cords<\/a>, which are needed to produce vocal sounds.<\/li>\n<li>The lower respiratory tract includes the trachea, bronchi and bronchioles, and the lungs. The trachea, bronchi, and bronchioles are involved in\u00a0conduction. Gas exchange takes place only in the lungs, which are the largest organs of the respiratory tract. Lung tissue consists mainly of tiny air sacs called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4311\">alveoli<\/a>, which is where gas exchange takes place between air in the alveoli and the blood in capillaries surrounding them.<\/li>\n<li>The respiratory system protects itself from potentially harmful substances in the air by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_5205_4318\">mucociliary escalator<\/a>. This includes mucus-producing cells, which trap particles and pathogens in incoming air. It also includes tiny hair-like cilia that continually move to sweep the mucus and trapped debris away from the lungs and toward the outside of the body.<\/li>\n<li>The level of carbon dioxide in the blood is monitored by cells in the brain. If the level becomes too high, it triggers a faster rate of breathing, which lowers the level to the normal range. The opposite occurs if the level becomes too\u00a0low. The respiratory system exchanges gases with the outside air, but it needs the\u00a0cardiovascular system\u00a0to carry the gases to and from cells throughout the body.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">13.2 Review Questions<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ol>\n<li>\n<div id=\"h5p-237\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-237\" class=\"h5p-iframe\" data-content-id=\"237\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13.2 Quiz\"><\/iframe><\/div>\n<\/div>\n<\/li>\n<li>What is respiration, as carried out by the respiratory system? Name the two subsidiary processes it involves.<\/li>\n<li>Describe the respiratory tract.<\/li>\n<li>Identify the organs of the upper respiratory tract.\u00a0What are their functions?<\/li>\n<li>List the organs of the lower respiratory tract. Which organs are involved only in conduction?<\/li>\n<li>Where does gas exchange take place?<\/li>\n<li>How does the respiratory system protect itself from potentially harmful substances in the air?<\/li>\n<li>Explain how the rate of breathing is controlled.<\/li>\n<li>Why does the respiratory system need the\u00a0cardiovascular system to help it perform its main function of gas exchange?<\/li>\n<li>Describe two ways in which the body prevents food from entering the lungs.<\/li>\n<li>What is the relationship between respiration and cellular respiration?<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">13.2 Explore More<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<p>https:\/\/www.youtube.com\/watch?v=8NUxvJS-_0k<\/p>\n<p style=\"text-align: center\">How do lungs work? - Emma Bryce, TED-Ed, 2014.<\/p>\n<p>https:\/\/www.youtube.com\/watch?time_continue=1&amp;v=6iFPs6JlSzY&amp;feature=emb_logo<\/p>\n<p style=\"text-align: center\">Why Do Men Have Deeper Voices? BrainStuff - HowStuffWorks, 2015.<\/p>\n<p>https:\/\/www.youtube.com\/watch?v=rjibeBSnpJ0<\/p>\n<p style=\"text-align: center\">Why does your voice change as you get older? - Shaylin A. Schundler, TED-Ed, 2018.<\/p>\n<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<\/div>\n<h2>Attributions<\/h2>\n<p><strong>Figure 13.2.1<\/strong><\/p>\n<p><a href=\"https:\/\/unsplash.com\/photos\/HYovA7yPPvI\" rel=\"cc:attributionURL\">Exhale by pavel-lozovikov-HYovA7yPPvI<\/a> [photo] by <a href=\"https:\/\/unsplash.com\/photos\/HYovA7yPPvI\">Pavel Lozovikov<\/a> on <a href=\"http:\/\/unsplash.com\">Unsplash<\/a> is used under the <a class=\"ICezk _2GAZm _2WvKc\" href=\"https:\/\/unsplash.com\/license\">Unsplash License<\/a> (https:\/\/unsplash.com\/license).<\/p>\n<p><strong>Figure 13.2.2<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Illu_conducting_passages.svg\" rel=\"cc:attributionURL\">Illu_conducting_passages.svg<\/a> by <a title=\"User:Lord Akryl\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Lord_Akryl\">Lord Akryl<\/a>,\u00a0<a title=\"User:Jmarchn\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Jmarchn\">Jmarchn<\/a> from <a href=\"https:\/\/training.seer.cancer.gov\/\">SEER Training Modules\/ National Cancer Institute<\/a> on Wikimedia Commons is in the <a class=\"extiw\" title=\"w:en:Public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:Public_domain\">public<\/a><a class=\"extiw\" title=\"w:en:Public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:Public_domain\"> domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/p>\n<p><strong>Figure 13.2.3<\/strong><\/p>\n<p><a href=\"http:\/\/www.medicalgraphics.de\/en\/free-pictures\/organe\/larynx.html\" rel=\"cc:attributionURL\">Larynx<\/a> by <a href=\"http:\/\/www.medicalgraphics.de\/en\/free-pictures\/organe\/larynx.html\">www.medicalgraphics.de<\/a>\u00a0 is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nd\/4.0\/\" rel=\"license\">CC BY-ND 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-nd\/4.0\/) license.<\/p>\n<p><strong>Figure 13.2.4<\/strong><\/p>\n<p><a href=\"https:\/\/visuals.nci.nih.gov\/details.cfm?imageid=4370\" rel=\"cc:attributionURL\">Larynx top view<\/a>\u00a0by Alan Hoofring (Illustrator) for <a href=\"https:\/\/visuals.nci.nih.gov\/details.cfm?imageid=4370\">National Cancer Institute<\/a> is in the <a class=\"extiw\" title=\"w:en:Public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:Public_domain\">public<\/a><a class=\"extiw\" title=\"w:en:Public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:Public_domain\"> domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/p>\n<p><strong>Figure 13.2.5<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lungs_diagram_detailed.svg\" rel=\"cc:attributionURL\">2000px-Lungs_diagram_detailed.svg<\/a> by <a class=\"mw-userlink\" title=\"User:Patrick.lynch\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Patrick.lynch\">Patrick J. Lynch<\/a>, medical illustrator on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.5\" rel=\"license\">CC BY 2.5<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.5) license.\u00a0(Derivative work of <a title=\"File:Fruchtwasserembolie.png\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Fruchtwasserembolie.png\">Fruchtwasserembolie.png.<\/a>)<\/p>\n<p><strong>Figure 13.2.6<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:2312_Gross_Anatomy_of_the_Lungs.jpg\" rel=\"cc:attributionURL\">Gross_Anatomy_of_the_Lungs<\/a> by <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/22-2-the-lungs\">OpenStax College<\/a> on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\" rel=\"license\">CC BY 3.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/3.0) license.<\/p>\n<p><strong>Figure 13.2.7<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Figure_39_01_09.jpg\" rel=\"cc:attributionURL\">Alveoli Structure<\/a>\u00a0by <a href=\"https:\/\/cnx.org\/contents\/GFy_h8cu@10.53:35-R0biq@11\/Systems-of-Gas-Exchange\">CNX OpenStax<\/a> on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" rel=\"license\">CC BY 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/4.0) license.<\/p>\n<p><strong>Figure 13.2.8<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:An_annotated_diagram_of_an_alveolus.svg\" rel=\"cc:attributionURL\">annotated_diagram_of_an_alveolus.svg<\/a> by <a class=\"new\" title=\"User:Katherinebutler1331 (page does not exist)\" href=\"https:\/\/commons.wikimedia.org\/w\/index.php?title=User:Katherinebutler1331&amp;action=edit&amp;redlink=1\">Katherinebutler1331<\/a> on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" rel=\"license\">CC BY-SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.<\/p>\n<p><strong>Figure 13.2.9<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sneeze.JPG\" rel=\"cc:attributionURL\">Sneeze<\/a> by James Gathany at <a href=\"https:\/\/phil.cdc.gov\/Details.aspx?pid=11162\">CDC Public Health Imagery Library (PHIL) #11162<\/a> on Wikimedia Commons is in the <a class=\"extiw\" title=\"w:en:Public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:Public_domain\">public<\/a><a class=\"extiw\" title=\"w:en:Public domain\" href=\"https:\/\/en.wikipedia.org\/wiki\/en:Public_domain\"> domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/p>\n<h2>References<\/h2>\n<p class=\"hanging-indent\"><span class=\"os-title-label\">Betts, J. G., Young, K.A., Wise, J.A., Johnson, E., Poe, B., Kruse, D.H., Korol, O., Johnson, J.E., Womble, M., DeSaix, P. (2013, June 19). <\/span>Figure 22.2 Major respiratory structures <span id=\"4572\" class=\"os-title\" data-type=\"title\"><span class=\"search-highlight first text last focus\" data-timestamp=\"1596823737203\" data-highlight-id=\"56d673ee-04fc-4187-a8ca-ee010b205bee\" data-highlighted=\"true\">[digital image].\u00a0 In<em> Anatomy and Physiology<\/em> (Section 22.1). OpenStax. https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/22-1-organs-and-structures-of-the-respiratory-system [CC BY 4.0 (https:\/\/creativecommons.org\/licenses\/by\/4.0)].<\/span><\/span><\/p>\n<p class=\"hanging-indent\"><span class=\"os-title-label\">Betts, J. G., Young, K.A., Wise, J.A., Johnson, E., Poe, B., Kruse, D.H., Korol, O., Johnson, J.E., Womble, M., DeSaix, P. (2013, June 19). Figure <\/span><span class=\"os-number\">22.13<\/span><span class=\"os-divider\">\u00a0<\/span><span id=\"4572\" class=\"os-title\" data-type=\"title\"><span class=\"search-highlight first text last focus\" data-timestamp=\"1596823737203\" data-highlight-id=\"56d673ee-04fc-4187-a8ca-ee010b205bee\" data-highlighted=\"true\">Gross anatomy of the lungs [digital image].\u00a0 In <em>Anatomy and Physiology<\/em> (Section 22.2). OpenStax. https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/22-2-the-lungs<\/span><\/span><\/p>\n<p class=\"hanging-indent\">BrainStuff - HowStuffWorks. (2015, December 1). Why do men have deeper voices?\u00a0 YouTube. https:\/\/www.youtube.com\/watch?v=6iFPs6JlSzY&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">Dr. Lotz. (2018, January 25). Larynx model - Respiratory system. YouTube. https:\/\/www.youtube.com\/watch?v=BsyB88mq5rQ&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">I-Hsun Wu. (<span style=\"font-size: 1em\">2015, March 31). <\/span>Mucociliary clearance. <span style=\"font-size: 1em\">YouTube. https:\/\/www.youtube.com\/watch?v=HMB6flEaZwI&amp;feature=youtu.be<\/span><\/p>\n<p class=\"hanging-indent\">OpenStax. (<span style=\"text-align: initial;font-size: 1em\">2016, May 27). <\/span>Figure 9 Terminal bronchioles are connected by respiratory bronchioles to alveolar ducts and alveolar sacs [digital image]. In <span style=\"font-size: 1em\"><em>OpenStax, Biology<\/em> (Section 39.1).<\/span><span style=\"font-size: 1em\">\u00a0<\/span><span style=\"text-align: initial;font-size: 1em\">OpenStax CNX. \u00a0https:\/\/cnx.org\/contents\/GFy_h8cu@10.53:35-R0biq@11\/Systems-of-Gas-Exchange<\/span><\/p>\n<p class=\"hanging-indent\">ProCPR. (2009, November 24). Conscious child choking. YouTube. https:\/\/www.youtube.com\/watch?v=ZjmbD7aIaf0&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">ProCPR. (2009, November 24).Unconscious child choking. YouTube. https:\/\/www.youtube.com\/watch?v=Sba0T2XGIn4&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">ProCPR. (2011, February 1). Conscious infant choking. YouTube. https:\/\/www.youtube.com\/watch?v=axqIju9CLKA&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">ProCPR. (2011, February 1). Unconscious adult choking. YouTube. https:\/\/www.youtube.com\/watch?v=5kmsKNvKAvU&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">ProCPR. (2011, February 1). Unconscious infant choking. YouTube. https:\/\/www.youtube.com\/watch?v=_K7Dwy6b2wQ&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">ProCPR. (2016, April 8). Conscious adult choking. YouTube. https:\/\/www.youtube.com\/watch?v=XOTbjDGZ7wg&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED-Ed. (2014, November 24). How do lungs work? - Emma Bryce. YouTube. https:\/\/www.youtube.com\/watch?v=8NUxvJS-_0k&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED-Ed. (2018, August 2). Why does your voice change as you get older? - Shaylin A. Schundler. 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