Case Study: Flight Risk<\/h1>\r\n<\/div>\r\nNineteen-year-old Malcolm is about to take his first plane flight. Shortly after he boards the plane and sits down, a man in his late sixties sits next to him in the aisle seat. About half an hour after the plane takes off, the pilot announces that she is turning the seat belt light off, and that it is safe to move around the cabin.\r\n\r\nThe man in the aisle seat \u2014 who has introduced himself to Malcolm as Willie \u2014 immediately unbuckles his seat belt and paces up and down the aisle a few times before returning to his seat. After about 45 minutes, Willie gets up again, walks some more, then sits back down and does some foot and leg exercises. After the third time Willie gets up and paces the aisles, Malcolm asks him whether he is walking so much to accumulate steps on a pedometer or fitness tracking device. Willie laughs and says no. He is actually trying to do something even more important for his health \u2014 prevent a blood clot from forming in his legs.\r\n\r\nWillie explains that he has a chronic condition: [pb_glossary id=\"4219\"]heart failure[\/pb_glossary]. Although it sounds scary, his condition is currently well-managed, and he is able to lead a relatively normal lifestyle. However, it does<\/em> put him at risk of developing other serious health conditions, such as deep vein thrombosis (DVT), which is when a blood clot occurs in the deep veins, usually in the legs. Air travel \u2014\u00a0and\u00a0other situations where a person has to sit for a long period of time \u2014 increases the risk of DVT. Willie\u2019s doctor said that he is healthy enough to fly, but that he should walk frequently and do leg exercises to help avoid a blood clot.\r\n\r\nAs you read this chapter, you will learn about the heart, blood vessels, and blood that make up the cardiovascular system, as well as disorders of the cardiovascular system, such as heart failure. At the end of the chapter you will learn more about why DVT occurs, why Willie has to take extra precautions when he flies, and what can be done to lower the risk of DVT and its potentially deadly consequences.\r\n\r\nChapter Overview: Cardiovascular System<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\nIn this chapter, you will learn about the cardiovascular system, which transports substances throughout the body. Specifically, you will learn about:\r\n\r\n \t- The major components of the [pb_glossary id=\"5927\"]cardiovascular system[\/pb_glossary]: the heart, blood vessels, and blood.<\/li>\r\n \t
- The functions of the cardiovascular system, including transporting needed substances (such as oxygen and nutrients) to the cells of the body, and picking up waste products.<\/li>\r\n \t
- How blood is oxygenated through the pulmonary circulation, which transports blood between the heart and lungs.<\/li>\r\n \t
- How blood is circulated throughout the body through the systemic circulation.<\/li>\r\n \t
- The components of blood \u2014 including plasma, red blood cells, white blood cells, and platelets \u2014 and their specific functions.<\/li>\r\n \t
- Types of blood vessels \u2014 including arteries, veins, and capillaries \u2014 and their functions, similarities, and differences.<\/li>\r\n \t
- The structure of the heart, how it pumps blood, and how contractions of the heart are controlled.<\/li>\r\n \t
- What blood pressure is and how it is regulated.<\/li>\r\n \t
- Blood disorders, including anemia, HIV, and leukemia.<\/li>\r\n \t
- Cardiovascular diseases (including heart attack, stroke, and angina), and the risk factors and precursors \u2014 such as high blood pressure and atherosclerosis \u2014 that contribute to them.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n\r\n\r\nAs you read the chapter, think about the following questions:\r\n
\r\n \t- What is heart failure?Why\u00a0do you think it increases the risk of DVT?<\/li>\r\n \t
- What is a blood clot? What are possible health consequences of blood clots?<\/li>\r\n \t
- Why do you think sitting for long periods of time increases the risk of DVT? Why does walking and exercising the legs help reduce this risk?<\/li>\r\n<\/ol>\r\n<\/div>\r\n
Attribution<\/h2>\r\nFigure 14.1.1<\/strong>\r\n\r\naircraft-1583871_1920<\/a> [photo] by olivier89<\/a> from Pixabay<\/a> is used under the Pixabay License<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).","rendered":" <\/p>\n![\"14.1.1](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/aircraft-1583871_1920-2.jpg\")
Figure 14.1.1 Got to keep that blood moving!<\/em><\/figcaption><\/figure>\n\nCase Study: Flight Risk<\/h1>\n<\/div>\n
Nineteen-year-old Malcolm is about to take his first plane flight. Shortly after he boards the plane and sits down, a man in his late sixties sits next to him in the aisle seat. About half an hour after the plane takes off, the pilot announces that she is turning the seat belt light off, and that it is safe to move around the cabin.<\/p>\n
The man in the aisle seat \u2014 who has introduced himself to Malcolm as Willie \u2014 immediately unbuckles his seat belt and paces up and down the aisle a few times before returning to his seat. After about 45 minutes, Willie gets up again, walks some more, then sits back down and does some foot and leg exercises. After the third time Willie gets up and paces the aisles, Malcolm asks him whether he is walking so much to accumulate steps on a pedometer or fitness tracking device. Willie laughs and says no. He is actually trying to do something even more important for his health \u2014 prevent a blood clot from forming in his legs.<\/p>\n
Willie explains that he has a chronic condition: heart failure<\/a>. Although it sounds scary, his condition is currently well-managed, and he is able to lead a relatively normal lifestyle. However, it does<\/em> put him at risk of developing other serious health conditions, such as deep vein thrombosis (DVT), which is when a blood clot occurs in the deep veins, usually in the legs. Air travel \u2014\u00a0and\u00a0other situations where a person has to sit for a long period of time \u2014 increases the risk of DVT. Willie\u2019s doctor said that he is healthy enough to fly, but that he should walk frequently and do leg exercises to help avoid a blood clot.<\/p>\nAs you read this chapter, you will learn about the heart, blood vessels, and blood that make up the cardiovascular system, as well as disorders of the cardiovascular system, such as heart failure. At the end of the chapter you will learn more about why DVT occurs, why Willie has to take extra precautions when he flies, and what can be done to lower the risk of DVT and its potentially deadly consequences.<\/p>\n
\n\nChapter Overview: Cardiovascular System<\/span><\/h1>\n<\/header>\n\nIn this chapter, you will learn about the cardiovascular system, which transports substances throughout the body. Specifically, you will learn about:<\/p>\n
\n- The major components of the cardiovascular system<\/a>: the heart, blood vessels, and blood.<\/li>\n
- The functions of the cardiovascular system, including transporting needed substances (such as oxygen and nutrients) to the cells of the body, and picking up waste products.<\/li>\n
- How blood is oxygenated through the pulmonary circulation, which transports blood between the heart and lungs.<\/li>\n
- How blood is circulated throughout the body through the systemic circulation.<\/li>\n
- The components of blood \u2014 including plasma, red blood cells, white blood cells, and platelets \u2014 and their specific functions.<\/li>\n
- Types of blood vessels \u2014 including arteries, veins, and capillaries \u2014 and their functions, similarities, and differences.<\/li>\n
- The structure of the heart, how it pumps blood, and how contractions of the heart are controlled.<\/li>\n
- What blood pressure is and how it is regulated.<\/li>\n
- Blood disorders, including anemia, HIV, and leukemia.<\/li>\n
- Cardiovascular diseases (including heart attack, stroke, and angina), and the risk factors and precursors \u2014 such as high blood pressure and atherosclerosis \u2014 that contribute to them.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n
As you read the chapter, think about the following questions:<\/p>\n
\n- What is heart failure?Why\u00a0do you think it increases the risk of DVT?<\/li>\n
- What is a blood clot? What are possible health consequences of blood clots?<\/li>\n
- Why do you think sitting for long periods of time increases the risk of DVT? Why does walking and exercising the legs help reduce this risk?<\/li>\n<\/ol>\n<\/div>\n
Attribution<\/h2>\n
Figure 14.1.1<\/strong><\/p>\naircraft-1583871_1920<\/a> [photo] by olivier89<\/a> from Pixabay<\/a> is used under the Pixabay License<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).<\/p>\ndefinition<\/span>Created by CK-12 Foundation\/Adapted by Christine Miller<\/p>\n![\"16.2.1](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/Chimneys-by-angela-baker-awlR2geeTGs-unsplash-scaled-2.jpg\")
Figure 16.2.1 Chimney view.<\/em><\/figcaption><\/figure>\n\nGetting Rid of Wastes<\/h1>\n<\/div>\n
The many chimneys on these houses are one way that the inhabitants of the home get rid of the wastes they produce. The chimneys expel waste gases that are created when they burn fuel in their furnace or fireplace. Think about the other wastes that people create in their homes and how we dispose of them. Solid trash and recyclables may go to the curb in a trash can, or in a recycling bin for pick up and transport to a landfill or recycling centre. Wastewater from sinks, showers, toilets, and the washing machine goes into a main sewer pipe and out of the house to join the community\u2019s sanitary sewer system.<\/p>\n
Like a busy home, your body also produces a lot of wastes that must be eliminated. Like a home,\u00a0the way\u00a0your body gets rid of wastes depends on the nature of the waste products. Some\u00a0human body\u00a0wastes are gases, some are solids, and some are in a\u00a0liquid\u00a0state. Getting rid of body wastes is called excretion, and there are a number of different\u00a0organs of excretion in the human body.<\/p>\n
\nExcretion<\/h3>\n<\/div>\n
Excretion<\/a><\/strong>\u00a0is the process of removing wastes and excess\u00a0water\u00a0from the body. It is an essential process in all living things, and it is one of the major ways the\u00a0human body\u00a0maintains\u00a0homeostasis<\/a>. It also helps prevent damage to the body. Wastes include by-products of metabolism<\/a> \u2014 some of which are toxic \u2014 and other non-useful materials, such as used up and broken down components. Some of the specific waste products that must be excreted from the body include carbon dioxide from\u00a0cellular respiration<\/a>, ammonia<\/a> and\u00a0urea<\/a><\/strong>\u00a0from\u00a0protein\u00a0catabolism, and\u00a0uric\u00a0acid<\/strong><\/a>\u00a0from\u00a0nucleic acid\u00a0catabolism.<\/p>\n\nExcretory Organs<\/h3>\n<\/div>\n
Organs of excretion include the skin<\/a>, liver<\/a>, large intestine<\/a>, lungs<\/a>, and kidneys<\/a> (see Figure 16.2.2). Together, these organs make up the excretory system<\/a><\/strong>.\u00a0They all\u00a0excrete wastes, but they don\u2019t work together in the same way that organs do in most other body systems. Each of the excretory organs \u201cdoes its own thing\u201d more-or-less independently of the others, but all are necessary to successfully excrete the full range of wastes from the\u00a0human body.<\/p>\n\n<\/div>\n<\/div>\n\nFigure 16.2.2 Internal organs of excretion are identified in this illustration. They include the skin, liver, large intestine, lungs, and kidneys.<\/em><\/p>\n<\/div>\nSkin<\/h2>\n![\"16.2.3](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/gym_room_fitness_equipment_cardiovascular_exercise_elliptical_bike_cardio_training_sports_equipment_bodybuilding-825364-1.jpg\")
Figure 16.2.3 The purpose of sweat production is mainly to cool the body and prevent overheating, but it also contributes to excretion.<\/em><\/figcaption><\/figure>\nThe skin<\/a> is part of the integumentary system, but it also plays a role in excretion through the production of sweat<\/a> by sweat glands in the dermis. Although the main role of sweat production is to cool the body and maintain temperature homeostasis<\/a>, sweating also eliminates excess water and salts, as well as a small amount of urea. When sweating is copious, as in Figure 16.2.3, ingestion of salts and water may be helpful to maintain homeostasis in the body.<\/p>\nLiver<\/h2>\n![\"16.2.4](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/liver-2934612_1280-1.png\")
Figure 16.2.4 The liver is an organ of excretion.<\/em><\/figcaption><\/figure>\nThe liver (shown in Figure 16.2.4) has numerous major functions, including secreting bile<\/a> for digestion of lipids, synthesizing many proteins and other compounds, storing glycogen and other substances, and secreting endocrine hormones. In addition to all of these functions, the liver is a very important organ of excretion. The liver breaks down many substances in the blood, including toxins. For example, the liver transforms ammonia<\/a> \u2014 a poisonous by-product of protein catabolism<\/a> \u2014 into urea<\/a>, which is filtered from the blood by the kidneys and excreted in urine. The liver also excretes in its bile the protein bilirubin<\/a>,<\/strong>\u00a0a byproduct of hemoglobin<\/a> catabolism<\/a> that forms when red\u00a0blood\u00a0cells\u00a0die. Bile travels to the\u00a0small intestine\u00a0and is then excreted in feces<\/a> by the\u00a0large intestine<\/a>.<\/p>\nLarge Intestine<\/h2>\n
The large intestine<\/a> is an important part of the digestive system and the final organ in the gastrointestinal tract. As an organ of excretion, its main function is to eliminate solid wastes that remain after the digestion of food and the extraction of water from indigestible matter in food waste. The large intestine also collects wastes from throughout the body. Bile<\/a> secreted into the gastrointestinal tract, for example, contains the waste product bilirubin<\/a> from the liver. Bilirubin is a brown pigment that gives human feces<\/a> its characteristic brown colour.<\/p>\nLungs<\/h2>\n
The lungs are part of the respiratory system (shown in Figure 16.2.5), but they are also important organs of excretion. They are responsible for the excretion of gaseous wastes from the body. The main waste gas excreted by the lungs is carbon dioxide, which is a waste product of cellular respiration<\/a> in cells throughout the body. Carbon dioxide is diffused from the blood into the air in the tiny air sacs called alveoli<\/a> in the lungs (shown in the inset diagram). By expelling carbon dioxide from the blood, the lungs help maintain acid-base homeostasis<\/a>. In fact, it is the pH of blood that controls the rate of breathing. Water vapor is also picked up from the lungs and other organs of the respiratory tract as the exhaled air passes over their moist linings, and the water vapor is excreted along with the carbon dioxide. Trace levels of some other waste gases are exhaled, as well.<\/p>\n![\"16.2.5](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/1024px-Respiratory_System_Illustration-1.png\")
Figure 16.2.5 The alveoli are the functional structures in the lungs where gaseous wastes enter the air from the blood.<\/figcaption><\/figure>\nKidneys<\/h2>\n
The paired kidneys are often considered the main organs of excretion. The primary function of the kidneys is the elimination of excess water and wastes from the bloodstream by the production of the\u00a0liquid\u00a0waste known as\u00a0urine<\/a><\/strong>. The main structural and functional units of the kidneys are tiny structures called nephrons.\u00a0Nephrons<\/a><\/strong> filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine. As shown in Figure 16.2.6, the kidneys are organs of the urinary system, which also includes the ureters, bladder, and urethra \u2014 organs that transport, store, and eliminate urine, respectively.<\/p>\n![\"16.2.6](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/512px-Urinary_System_Female-1.png\")
Figure 16.2.6 The urinary system consists of two kidneys and the structures that transport and store urine.<\/em><\/figcaption><\/figure>\nBy producing and excreting urine, the kidneys play vital roles in body-wide homeostasis<\/a>. They maintain the correct volume of extracellular fluid, which is all the fluid in the body outside of cells, including the blood and lymph. The kidneys also maintain the correct balance of salts and pH in extracellular fluid. In addition, the kidneys function as endocrine glands, secreting hormones into the blood that control other body processes. You can read much more about the kidneys in section 16.4 Kidneys<\/a>.<\/p>\n\n\n\n16.2 Summary<\/span><\/h1>\n<\/header>\n\n\n- Excretion<\/a> is the process of removing wastes and excess water from the body. It is an essential process in all living things and a major way the human body maintains homeostasis<\/a>.<\/li>\n
- Organs of excretion include the skin, liver, large intestine, lungs, and kidneys. All of them excrete wastes, and together they make up the excretory system<\/a>.<\/li>\n
- The skin<\/a> plays a role in excretion through the production of sweat by sweat glands. Sweating eliminates excess water and salts, as well as a small amount of urea<\/a>, a byproduct of\u00a0protein\u00a0catabolism.<\/li>\n
- The liver<\/a> is a very important organ of excretion. The liver breaks down many substances in the blood, including toxins. The liver also excretes bilirubin<\/a> \u2014 a waste product of hemoglobin<\/a> catabolism<\/a> \u2014 in bile. Bile then travels to the\u00a0small intestine<\/a>, and is eventually excreted in feces<\/a> by the large intestine<\/a>.<\/li>\n
- The main excretory function of the large intestine is to eliminate\u00a0solid waste that remains after food is digested and water is extracted from the indigestible matter. The large intestine also collects and excretes wastes from throughout the body, including bilirubin in bile<\/a>.<\/li>\n
- The lungs<\/a> are responsible for the excretion of gaseous wastes, primarily carbon dioxide from\u00a0cellular respiration<\/a>\u00a0in cells throughout the body. Exhaled air also contains water vapor and trace levels of some other waste gases.<\/li>\n
- The paired kidneys<\/a> are often considered the main organs of excretion. Their primary function is the elimination of excess water and wastes from the bloodstream by the production of urine. The kidneys contain tiny structures called nephrons<\/a>\u00a0that filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine<\/a>. The kidneys are part of the\u00a0urinary system, which also includes the\u00a0ureters, urinary bladder, and urethra.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n
\n16.2 Review Questions<\/span><\/h1>\n<\/header>\n\n\n- What is excretion, and what is its significance?<\/li>\n
- \n\n
Chapter Overview: Cardiovascular System<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\nIn this chapter, you will learn about the cardiovascular system, which transports substances throughout the body. Specifically, you will learn about:\r\n\r\n \t- The major components of the [pb_glossary id=\"5927\"]cardiovascular system[\/pb_glossary]: the heart, blood vessels, and blood.<\/li>\r\n \t
- The functions of the cardiovascular system, including transporting needed substances (such as oxygen and nutrients) to the cells of the body, and picking up waste products.<\/li>\r\n \t
- How blood is oxygenated through the pulmonary circulation, which transports blood between the heart and lungs.<\/li>\r\n \t
- How blood is circulated throughout the body through the systemic circulation.<\/li>\r\n \t
- The components of blood \u2014 including plasma, red blood cells, white blood cells, and platelets \u2014 and their specific functions.<\/li>\r\n \t
- Types of blood vessels \u2014 including arteries, veins, and capillaries \u2014 and their functions, similarities, and differences.<\/li>\r\n \t
- The structure of the heart, how it pumps blood, and how contractions of the heart are controlled.<\/li>\r\n \t
- What blood pressure is and how it is regulated.<\/li>\r\n \t
- Blood disorders, including anemia, HIV, and leukemia.<\/li>\r\n \t
- Cardiovascular diseases (including heart attack, stroke, and angina), and the risk factors and precursors \u2014 such as high blood pressure and atherosclerosis \u2014 that contribute to them.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n\r\n\r\nAs you read the chapter, think about the following questions:\r\n
\r\n \t- What is heart failure?Why\u00a0do you think it increases the risk of DVT?<\/li>\r\n \t
- What is a blood clot? What are possible health consequences of blood clots?<\/li>\r\n \t
- Why do you think sitting for long periods of time increases the risk of DVT? Why does walking and exercising the legs help reduce this risk?<\/li>\r\n<\/ol>\r\n<\/div>\r\n
Attribution<\/h2>\r\nFigure 14.1.1<\/strong>\r\n\r\naircraft-1583871_1920<\/a> [photo] by olivier89<\/a> from Pixabay<\/a> is used under the Pixabay License<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).","rendered":" <\/p>\nFigure 14.1.1 Got to keep that blood moving!<\/em><\/figcaption><\/figure>\n\nCase Study: Flight Risk<\/h1>\n<\/div>\n
Nineteen-year-old Malcolm is about to take his first plane flight. Shortly after he boards the plane and sits down, a man in his late sixties sits next to him in the aisle seat. About half an hour after the plane takes off, the pilot announces that she is turning the seat belt light off, and that it is safe to move around the cabin.<\/p>\n
The man in the aisle seat \u2014 who has introduced himself to Malcolm as Willie \u2014 immediately unbuckles his seat belt and paces up and down the aisle a few times before returning to his seat. After about 45 minutes, Willie gets up again, walks some more, then sits back down and does some foot and leg exercises. After the third time Willie gets up and paces the aisles, Malcolm asks him whether he is walking so much to accumulate steps on a pedometer or fitness tracking device. Willie laughs and says no. He is actually trying to do something even more important for his health \u2014 prevent a blood clot from forming in his legs.<\/p>\n
Willie explains that he has a chronic condition: heart failure<\/a>. Although it sounds scary, his condition is currently well-managed, and he is able to lead a relatively normal lifestyle. However, it does<\/em> put him at risk of developing other serious health conditions, such as deep vein thrombosis (DVT), which is when a blood clot occurs in the deep veins, usually in the legs. Air travel \u2014\u00a0and\u00a0other situations where a person has to sit for a long period of time \u2014 increases the risk of DVT. Willie\u2019s doctor said that he is healthy enough to fly, but that he should walk frequently and do leg exercises to help avoid a blood clot.<\/p>\nAs you read this chapter, you will learn about the heart, blood vessels, and blood that make up the cardiovascular system, as well as disorders of the cardiovascular system, such as heart failure. At the end of the chapter you will learn more about why DVT occurs, why Willie has to take extra precautions when he flies, and what can be done to lower the risk of DVT and its potentially deadly consequences.<\/p>\n
\n\nChapter Overview: Cardiovascular System<\/span><\/h1>\n<\/header>\n\nIn this chapter, you will learn about the cardiovascular system, which transports substances throughout the body. Specifically, you will learn about:<\/p>\n
\n- The major components of the cardiovascular system<\/a>: the heart, blood vessels, and blood.<\/li>\n
- The functions of the cardiovascular system, including transporting needed substances (such as oxygen and nutrients) to the cells of the body, and picking up waste products.<\/li>\n
- How blood is oxygenated through the pulmonary circulation, which transports blood between the heart and lungs.<\/li>\n
- How blood is circulated throughout the body through the systemic circulation.<\/li>\n
- The components of blood \u2014 including plasma, red blood cells, white blood cells, and platelets \u2014 and their specific functions.<\/li>\n
- Types of blood vessels \u2014 including arteries, veins, and capillaries \u2014 and their functions, similarities, and differences.<\/li>\n
- The structure of the heart, how it pumps blood, and how contractions of the heart are controlled.<\/li>\n
- What blood pressure is and how it is regulated.<\/li>\n
- Blood disorders, including anemia, HIV, and leukemia.<\/li>\n
- Cardiovascular diseases (including heart attack, stroke, and angina), and the risk factors and precursors \u2014 such as high blood pressure and atherosclerosis \u2014 that contribute to them.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n
As you read the chapter, think about the following questions:<\/p>\n
\n- What is heart failure?Why\u00a0do you think it increases the risk of DVT?<\/li>\n
- What is a blood clot? What are possible health consequences of blood clots?<\/li>\n
- Why do you think sitting for long periods of time increases the risk of DVT? Why does walking and exercising the legs help reduce this risk?<\/li>\n<\/ol>\n<\/div>\n
Attribution<\/h2>\n
Figure 14.1.1<\/strong><\/p>\naircraft-1583871_1920<\/a> [photo] by olivier89<\/a> from Pixabay<\/a> is used under the Pixabay License<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).<\/p>\ndefinition<\/span>Created by CK-12 Foundation\/Adapted by Christine Miller<\/p>\nFigure 16.2.1 Chimney view.<\/em><\/figcaption><\/figure>\n\nGetting Rid of Wastes<\/h1>\n<\/div>\n
The many chimneys on these houses are one way that the inhabitants of the home get rid of the wastes they produce. The chimneys expel waste gases that are created when they burn fuel in their furnace or fireplace. Think about the other wastes that people create in their homes and how we dispose of them. Solid trash and recyclables may go to the curb in a trash can, or in a recycling bin for pick up and transport to a landfill or recycling centre. Wastewater from sinks, showers, toilets, and the washing machine goes into a main sewer pipe and out of the house to join the community\u2019s sanitary sewer system.<\/p>\n
Like a busy home, your body also produces a lot of wastes that must be eliminated. Like a home,\u00a0the way\u00a0your body gets rid of wastes depends on the nature of the waste products. Some\u00a0human body\u00a0wastes are gases, some are solids, and some are in a\u00a0liquid\u00a0state. Getting rid of body wastes is called excretion, and there are a number of different\u00a0organs of excretion in the human body.<\/p>\n
\nExcretion<\/h3>\n<\/div>\n
Excretion<\/a><\/strong>\u00a0is the process of removing wastes and excess\u00a0water\u00a0from the body. It is an essential process in all living things, and it is one of the major ways the\u00a0human body\u00a0maintains\u00a0homeostasis<\/a>. It also helps prevent damage to the body. Wastes include by-products of metabolism<\/a> \u2014 some of which are toxic \u2014 and other non-useful materials, such as used up and broken down components. Some of the specific waste products that must be excreted from the body include carbon dioxide from\u00a0cellular respiration<\/a>, ammonia<\/a> and\u00a0urea<\/a><\/strong>\u00a0from\u00a0protein\u00a0catabolism, and\u00a0uric\u00a0acid<\/strong><\/a>\u00a0from\u00a0nucleic acid\u00a0catabolism.<\/p>\n\nExcretory Organs<\/h3>\n<\/div>\n
Organs of excretion include the skin<\/a>, liver<\/a>, large intestine<\/a>, lungs<\/a>, and kidneys<\/a> (see Figure 16.2.2). Together, these organs make up the excretory system<\/a><\/strong>.\u00a0They all\u00a0excrete wastes, but they don\u2019t work together in the same way that organs do in most other body systems. Each of the excretory organs \u201cdoes its own thing\u201d more-or-less independently of the others, but all are necessary to successfully excrete the full range of wastes from the\u00a0human body.<\/p>\n\n<\/div>\n<\/div>\n\nFigure 16.2.2 Internal organs of excretion are identified in this illustration. They include the skin, liver, large intestine, lungs, and kidneys.<\/em><\/p>\n<\/div>\nSkin<\/h2>\nFigure 16.2.3 The purpose of sweat production is mainly to cool the body and prevent overheating, but it also contributes to excretion.<\/em><\/figcaption><\/figure>\nThe skin<\/a> is part of the integumentary system, but it also plays a role in excretion through the production of sweat<\/a> by sweat glands in the dermis. Although the main role of sweat production is to cool the body and maintain temperature homeostasis<\/a>, sweating also eliminates excess water and salts, as well as a small amount of urea. When sweating is copious, as in Figure 16.2.3, ingestion of salts and water may be helpful to maintain homeostasis in the body.<\/p>\nLiver<\/h2>\nFigure 16.2.4 The liver is an organ of excretion.<\/em><\/figcaption><\/figure>\nThe liver (shown in Figure 16.2.4) has numerous major functions, including secreting bile<\/a> for digestion of lipids, synthesizing many proteins and other compounds, storing glycogen and other substances, and secreting endocrine hormones. In addition to all of these functions, the liver is a very important organ of excretion. The liver breaks down many substances in the blood, including toxins. For example, the liver transforms ammonia<\/a> \u2014 a poisonous by-product of protein catabolism<\/a> \u2014 into urea<\/a>, which is filtered from the blood by the kidneys and excreted in urine. The liver also excretes in its bile the protein bilirubin<\/a>,<\/strong>\u00a0a byproduct of hemoglobin<\/a> catabolism<\/a> that forms when red\u00a0blood\u00a0cells\u00a0die. Bile travels to the\u00a0small intestine\u00a0and is then excreted in feces<\/a> by the\u00a0large intestine<\/a>.<\/p>\nLarge Intestine<\/h2>\n
The large intestine<\/a> is an important part of the digestive system and the final organ in the gastrointestinal tract. As an organ of excretion, its main function is to eliminate solid wastes that remain after the digestion of food and the extraction of water from indigestible matter in food waste. The large intestine also collects wastes from throughout the body. Bile<\/a> secreted into the gastrointestinal tract, for example, contains the waste product bilirubin<\/a> from the liver. Bilirubin is a brown pigment that gives human feces<\/a> its characteristic brown colour.<\/p>\nLungs<\/h2>\n
The lungs are part of the respiratory system (shown in Figure 16.2.5), but they are also important organs of excretion. They are responsible for the excretion of gaseous wastes from the body. The main waste gas excreted by the lungs is carbon dioxide, which is a waste product of cellular respiration<\/a> in cells throughout the body. Carbon dioxide is diffused from the blood into the air in the tiny air sacs called alveoli<\/a> in the lungs (shown in the inset diagram). By expelling carbon dioxide from the blood, the lungs help maintain acid-base homeostasis<\/a>. In fact, it is the pH of blood that controls the rate of breathing. Water vapor is also picked up from the lungs and other organs of the respiratory tract as the exhaled air passes over their moist linings, and the water vapor is excreted along with the carbon dioxide. Trace levels of some other waste gases are exhaled, as well.<\/p>\nFigure 16.2.5 The alveoli are the functional structures in the lungs where gaseous wastes enter the air from the blood.<\/figcaption><\/figure>\nKidneys<\/h2>\n
The paired kidneys are often considered the main organs of excretion. The primary function of the kidneys is the elimination of excess water and wastes from the bloodstream by the production of the\u00a0liquid\u00a0waste known as\u00a0urine<\/a><\/strong>. The main structural and functional units of the kidneys are tiny structures called nephrons.\u00a0Nephrons<\/a><\/strong> filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine. As shown in Figure 16.2.6, the kidneys are organs of the urinary system, which also includes the ureters, bladder, and urethra \u2014 organs that transport, store, and eliminate urine, respectively.<\/p>\nFigure 16.2.6 The urinary system consists of two kidneys and the structures that transport and store urine.<\/em><\/figcaption><\/figure>\nBy producing and excreting urine, the kidneys play vital roles in body-wide homeostasis<\/a>. They maintain the correct volume of extracellular fluid, which is all the fluid in the body outside of cells, including the blood and lymph. The kidneys also maintain the correct balance of salts and pH in extracellular fluid. In addition, the kidneys function as endocrine glands, secreting hormones into the blood that control other body processes. You can read much more about the kidneys in section 16.4 Kidneys<\/a>.<\/p>\n\n\n\n16.2 Summary<\/span><\/h1>\n<\/header>\n\n\n- Excretion<\/a> is the process of removing wastes and excess water from the body. It is an essential process in all living things and a major way the human body maintains homeostasis<\/a>.<\/li>\n
- Organs of excretion include the skin, liver, large intestine, lungs, and kidneys. All of them excrete wastes, and together they make up the excretory system<\/a>.<\/li>\n
- The skin<\/a> plays a role in excretion through the production of sweat by sweat glands. Sweating eliminates excess water and salts, as well as a small amount of urea<\/a>, a byproduct of\u00a0protein\u00a0catabolism.<\/li>\n
- The liver<\/a> is a very important organ of excretion. The liver breaks down many substances in the blood, including toxins. The liver also excretes bilirubin<\/a> \u2014 a waste product of hemoglobin<\/a> catabolism<\/a> \u2014 in bile. Bile then travels to the\u00a0small intestine<\/a>, and is eventually excreted in feces<\/a> by the large intestine<\/a>.<\/li>\n
- The main excretory function of the large intestine is to eliminate\u00a0solid waste that remains after food is digested and water is extracted from the indigestible matter. The large intestine also collects and excretes wastes from throughout the body, including bilirubin in bile<\/a>.<\/li>\n
- The lungs<\/a> are responsible for the excretion of gaseous wastes, primarily carbon dioxide from\u00a0cellular respiration<\/a>\u00a0in cells throughout the body. Exhaled air also contains water vapor and trace levels of some other waste gases.<\/li>\n
- The paired kidneys<\/a> are often considered the main organs of excretion. Their primary function is the elimination of excess water and wastes from the bloodstream by the production of urine. The kidneys contain tiny structures called nephrons<\/a>\u00a0that filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine<\/a>. The kidneys are part of the\u00a0urinary system, which also includes the\u00a0ureters, urinary bladder, and urethra.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n
\n16.2 Review Questions<\/span><\/h1>\n<\/header>\n\n\n- What is excretion, and what is its significance?<\/li>\n
- \n\n
- \r\n \t
- The major components of the [pb_glossary id=\"5927\"]cardiovascular system[\/pb_glossary]: the heart, blood vessels, and blood.<\/li>\r\n \t
- The functions of the cardiovascular system, including transporting needed substances (such as oxygen and nutrients) to the cells of the body, and picking up waste products.<\/li>\r\n \t
- How blood is oxygenated through the pulmonary circulation, which transports blood between the heart and lungs.<\/li>\r\n \t
- How blood is circulated throughout the body through the systemic circulation.<\/li>\r\n \t
- The components of blood \u2014 including plasma, red blood cells, white blood cells, and platelets \u2014 and their specific functions.<\/li>\r\n \t
- Types of blood vessels \u2014 including arteries, veins, and capillaries \u2014 and their functions, similarities, and differences.<\/li>\r\n \t
- The structure of the heart, how it pumps blood, and how contractions of the heart are controlled.<\/li>\r\n \t
- What blood pressure is and how it is regulated.<\/li>\r\n \t
- Blood disorders, including anemia, HIV, and leukemia.<\/li>\r\n \t
- Cardiovascular diseases (including heart attack, stroke, and angina), and the risk factors and precursors \u2014 such as high blood pressure and atherosclerosis \u2014 that contribute to them.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n\r\n\r\nAs you read the chapter, think about the following questions:\r\n
- \r\n \t
- What is heart failure?Why\u00a0do you think it increases the risk of DVT?<\/li>\r\n \t
- What is a blood clot? What are possible health consequences of blood clots?<\/li>\r\n \t
- Why do you think sitting for long periods of time increases the risk of DVT? Why does walking and exercising the legs help reduce this risk?<\/li>\r\n<\/ol>\r\n<\/div>\r\n
Attribution<\/h2>\r\nFigure 14.1.1<\/strong>\r\n\r\naircraft-1583871_1920<\/a> [photo] by olivier89<\/a> from Pixabay<\/a> is used under the Pixabay License<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).","rendered":"
<\/p>\n
Figure 14.1.1 Got to keep that blood moving!<\/em><\/figcaption><\/figure>\n \nCase Study: Flight Risk<\/h1>\n<\/div>\n
Nineteen-year-old Malcolm is about to take his first plane flight. Shortly after he boards the plane and sits down, a man in his late sixties sits next to him in the aisle seat. About half an hour after the plane takes off, the pilot announces that she is turning the seat belt light off, and that it is safe to move around the cabin.<\/p>\n
The man in the aisle seat \u2014 who has introduced himself to Malcolm as Willie \u2014 immediately unbuckles his seat belt and paces up and down the aisle a few times before returning to his seat. After about 45 minutes, Willie gets up again, walks some more, then sits back down and does some foot and leg exercises. After the third time Willie gets up and paces the aisles, Malcolm asks him whether he is walking so much to accumulate steps on a pedometer or fitness tracking device. Willie laughs and says no. He is actually trying to do something even more important for his health \u2014 prevent a blood clot from forming in his legs.<\/p>\n
Willie explains that he has a chronic condition: heart failure<\/a>. Although it sounds scary, his condition is currently well-managed, and he is able to lead a relatively normal lifestyle. However, it does<\/em> put him at risk of developing other serious health conditions, such as deep vein thrombosis (DVT), which is when a blood clot occurs in the deep veins, usually in the legs. Air travel \u2014\u00a0and\u00a0other situations where a person has to sit for a long period of time \u2014 increases the risk of DVT. Willie\u2019s doctor said that he is healthy enough to fly, but that he should walk frequently and do leg exercises to help avoid a blood clot.<\/p>\n
As you read this chapter, you will learn about the heart, blood vessels, and blood that make up the cardiovascular system, as well as disorders of the cardiovascular system, such as heart failure. At the end of the chapter you will learn more about why DVT occurs, why Willie has to take extra precautions when he flies, and what can be done to lower the risk of DVT and its potentially deadly consequences.<\/p>\n
\n\n Chapter Overview: Cardiovascular System<\/span><\/h1>\n<\/header>\n
\nIn this chapter, you will learn about the cardiovascular system, which transports substances throughout the body. Specifically, you will learn about:<\/p>\n
- \n
- The major components of the cardiovascular system<\/a>: the heart, blood vessels, and blood.<\/li>\n
- The functions of the cardiovascular system, including transporting needed substances (such as oxygen and nutrients) to the cells of the body, and picking up waste products.<\/li>\n
- How blood is oxygenated through the pulmonary circulation, which transports blood between the heart and lungs.<\/li>\n
- How blood is circulated throughout the body through the systemic circulation.<\/li>\n
- The components of blood \u2014 including plasma, red blood cells, white blood cells, and platelets \u2014 and their specific functions.<\/li>\n
- Types of blood vessels \u2014 including arteries, veins, and capillaries \u2014 and their functions, similarities, and differences.<\/li>\n
- The structure of the heart, how it pumps blood, and how contractions of the heart are controlled.<\/li>\n
- What blood pressure is and how it is regulated.<\/li>\n
- Blood disorders, including anemia, HIV, and leukemia.<\/li>\n
- Cardiovascular diseases (including heart attack, stroke, and angina), and the risk factors and precursors \u2014 such as high blood pressure and atherosclerosis \u2014 that contribute to them.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n
\nAs you read the chapter, think about the following questions:<\/p>\n
- \n
- What is heart failure?Why\u00a0do you think it increases the risk of DVT?<\/li>\n
- What is a blood clot? What are possible health consequences of blood clots?<\/li>\n
- Why do you think sitting for long periods of time increases the risk of DVT? Why does walking and exercising the legs help reduce this risk?<\/li>\n<\/ol>\n<\/div>\n
Attribution<\/h2>\n
Figure 14.1.1<\/strong><\/p>\n
aircraft-1583871_1920<\/a> [photo] by olivier89<\/a> from Pixabay<\/a> is used under the Pixabay License<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).<\/p>\n
definition<\/span>Created by CK-12 Foundation\/Adapted by Christine Miller<\/p>\n
Figure 16.2.1 Chimney view.<\/em><\/figcaption><\/figure>\n \nGetting Rid of Wastes<\/h1>\n<\/div>\n
The many chimneys on these houses are one way that the inhabitants of the home get rid of the wastes they produce. The chimneys expel waste gases that are created when they burn fuel in their furnace or fireplace. Think about the other wastes that people create in their homes and how we dispose of them. Solid trash and recyclables may go to the curb in a trash can, or in a recycling bin for pick up and transport to a landfill or recycling centre. Wastewater from sinks, showers, toilets, and the washing machine goes into a main sewer pipe and out of the house to join the community\u2019s sanitary sewer system.<\/p>\n
Like a busy home, your body also produces a lot of wastes that must be eliminated. Like a home,\u00a0the way\u00a0your body gets rid of wastes depends on the nature of the waste products. Some\u00a0human body\u00a0wastes are gases, some are solids, and some are in a\u00a0liquid\u00a0state. Getting rid of body wastes is called excretion, and there are a number of different\u00a0organs of excretion in the human body.<\/p>\n
\nExcretion<\/h3>\n<\/div>\n
Excretion<\/a><\/strong>\u00a0is the process of removing wastes and excess\u00a0water\u00a0from the body. It is an essential process in all living things, and it is one of the major ways the\u00a0human body\u00a0maintains\u00a0homeostasis<\/a>. It also helps prevent damage to the body. Wastes include by-products of metabolism<\/a> \u2014 some of which are toxic \u2014 and other non-useful materials, such as used up and broken down components. Some of the specific waste products that must be excreted from the body include carbon dioxide from\u00a0cellular respiration<\/a>, ammonia<\/a> and\u00a0urea<\/a><\/strong>\u00a0from\u00a0protein\u00a0catabolism, and\u00a0uric\u00a0acid<\/strong><\/a>\u00a0from\u00a0nucleic acid\u00a0catabolism.<\/p>\n
\nExcretory Organs<\/h3>\n<\/div>\n
Organs of excretion include the skin<\/a>, liver<\/a>, large intestine<\/a>, lungs<\/a>, and kidneys<\/a> (see Figure 16.2.2). Together, these organs make up the excretory system<\/a><\/strong>.\u00a0They all\u00a0excrete wastes, but they don\u2019t work together in the same way that organs do in most other body systems. Each of the excretory organs \u201cdoes its own thing\u201d more-or-less independently of the others, but all are necessary to successfully excrete the full range of wastes from the\u00a0human body.<\/p>\n
\n<\/div>\n<\/div>\n\nFigure 16.2.2 Internal organs of excretion are identified in this illustration. They include the skin, liver, large intestine, lungs, and kidneys.<\/em><\/p>\n<\/div>\n
Skin<\/h2>\n
Figure 16.2.3 The purpose of sweat production is mainly to cool the body and prevent overheating, but it also contributes to excretion.<\/em><\/figcaption><\/figure>\n The skin<\/a> is part of the integumentary system, but it also plays a role in excretion through the production of sweat<\/a> by sweat glands in the dermis. Although the main role of sweat production is to cool the body and maintain temperature homeostasis<\/a>, sweating also eliminates excess water and salts, as well as a small amount of urea. When sweating is copious, as in Figure 16.2.3, ingestion of salts and water may be helpful to maintain homeostasis in the body.<\/p>\n
Liver<\/h2>\n
Figure 16.2.4 The liver is an organ of excretion.<\/em><\/figcaption><\/figure>\n The liver (shown in Figure 16.2.4) has numerous major functions, including secreting bile<\/a> for digestion of lipids, synthesizing many proteins and other compounds, storing glycogen and other substances, and secreting endocrine hormones. In addition to all of these functions, the liver is a very important organ of excretion. The liver breaks down many substances in the blood, including toxins. For example, the liver transforms ammonia<\/a> \u2014 a poisonous by-product of protein catabolism<\/a> \u2014 into urea<\/a>, which is filtered from the blood by the kidneys and excreted in urine. The liver also excretes in its bile the protein bilirubin<\/a>,<\/strong>\u00a0a byproduct of hemoglobin<\/a> catabolism<\/a> that forms when red\u00a0blood\u00a0cells\u00a0die. Bile travels to the\u00a0small intestine\u00a0and is then excreted in feces<\/a> by the\u00a0large intestine<\/a>.<\/p>\n
Large Intestine<\/h2>\n
The large intestine<\/a> is an important part of the digestive system and the final organ in the gastrointestinal tract. As an organ of excretion, its main function is to eliminate solid wastes that remain after the digestion of food and the extraction of water from indigestible matter in food waste. The large intestine also collects wastes from throughout the body. Bile<\/a> secreted into the gastrointestinal tract, for example, contains the waste product bilirubin<\/a> from the liver. Bilirubin is a brown pigment that gives human feces<\/a> its characteristic brown colour.<\/p>\n
Lungs<\/h2>\n
The lungs are part of the respiratory system (shown in Figure 16.2.5), but they are also important organs of excretion. They are responsible for the excretion of gaseous wastes from the body. The main waste gas excreted by the lungs is carbon dioxide, which is a waste product of cellular respiration<\/a> in cells throughout the body. Carbon dioxide is diffused from the blood into the air in the tiny air sacs called alveoli<\/a> in the lungs (shown in the inset diagram). By expelling carbon dioxide from the blood, the lungs help maintain acid-base homeostasis<\/a>. In fact, it is the pH of blood that controls the rate of breathing. Water vapor is also picked up from the lungs and other organs of the respiratory tract as the exhaled air passes over their moist linings, and the water vapor is excreted along with the carbon dioxide. Trace levels of some other waste gases are exhaled, as well.<\/p>\n
Figure 16.2.5 The alveoli are the functional structures in the lungs where gaseous wastes enter the air from the blood.<\/figcaption><\/figure>\n Kidneys<\/h2>\n
The paired kidneys are often considered the main organs of excretion. The primary function of the kidneys is the elimination of excess water and wastes from the bloodstream by the production of the\u00a0liquid\u00a0waste known as\u00a0urine<\/a><\/strong>. The main structural and functional units of the kidneys are tiny structures called nephrons.\u00a0Nephrons<\/a><\/strong> filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine. As shown in Figure 16.2.6, the kidneys are organs of the urinary system, which also includes the ureters, bladder, and urethra \u2014 organs that transport, store, and eliminate urine, respectively.<\/p>\n
Figure 16.2.6 The urinary system consists of two kidneys and the structures that transport and store urine.<\/em><\/figcaption><\/figure>\n By producing and excreting urine, the kidneys play vital roles in body-wide homeostasis<\/a>. They maintain the correct volume of extracellular fluid, which is all the fluid in the body outside of cells, including the blood and lymph. The kidneys also maintain the correct balance of salts and pH in extracellular fluid. In addition, the kidneys function as endocrine glands, secreting hormones into the blood that control other body processes. You can read much more about the kidneys in section 16.4 Kidneys<\/a>.<\/p>\n
\n\n\n 16.2 Summary<\/span><\/h1>\n<\/header>\n
\n- \n
- Excretion<\/a> is the process of removing wastes and excess water from the body. It is an essential process in all living things and a major way the human body maintains homeostasis<\/a>.<\/li>\n
- Organs of excretion include the skin, liver, large intestine, lungs, and kidneys. All of them excrete wastes, and together they make up the excretory system<\/a>.<\/li>\n
- The skin<\/a> plays a role in excretion through the production of sweat by sweat glands. Sweating eliminates excess water and salts, as well as a small amount of urea<\/a>, a byproduct of\u00a0protein\u00a0catabolism.<\/li>\n
- The liver<\/a> is a very important organ of excretion. The liver breaks down many substances in the blood, including toxins. The liver also excretes bilirubin<\/a> \u2014 a waste product of hemoglobin<\/a> catabolism<\/a> \u2014 in bile. Bile then travels to the\u00a0small intestine<\/a>, and is eventually excreted in feces<\/a> by the large intestine<\/a>.<\/li>\n
- The main excretory function of the large intestine is to eliminate\u00a0solid waste that remains after food is digested and water is extracted from the indigestible matter. The large intestine also collects and excretes wastes from throughout the body, including bilirubin in bile<\/a>.<\/li>\n
- The lungs<\/a> are responsible for the excretion of gaseous wastes, primarily carbon dioxide from\u00a0cellular respiration<\/a>\u00a0in cells throughout the body. Exhaled air also contains water vapor and trace levels of some other waste gases.<\/li>\n
- The paired kidneys<\/a> are often considered the main organs of excretion. Their primary function is the elimination of excess water and wastes from the bloodstream by the production of urine. The kidneys contain tiny structures called nephrons<\/a>\u00a0that filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine<\/a>. The kidneys are part of the\u00a0urinary system, which also includes the\u00a0ureters, urinary bladder, and urethra.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n
\n\n 16.2 Review Questions<\/span><\/h1>\n<\/header>\n
\n- \n
- What is excretion, and what is its significance?<\/li>\n
- \n\n
- Organs of excretion include the skin, liver, large intestine, lungs, and kidneys. All of them excrete wastes, and together they make up the excretory system<\/a>.<\/li>\n
- Excretion<\/a> is the process of removing wastes and excess water from the body. It is an essential process in all living things and a major way the human body maintains homeostasis<\/a>.<\/li>\n
- The major components of the cardiovascular system<\/a>: the heart, blood vessels, and blood.<\/li>\n