Circulation Chapter 23

Cardiovascular System 4/23/2017 Cardiovascular System Accepts oxygen, nutrients, and other substances from the respiratory and digestive systems and delivers them to cells Accepts carbon dioxide and wastes from cells and delivers them to respiratory and urinary systems for disposal

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Chambers of heart RIGHT ATRIUM RIGHT VENTRICLE LEFT ATRIUM 4/23/2017 Chambers of heart RIGHT ATRIUM RIGHT VENTRICLE LEFT ATRIUM LEFT VENTRICLE

4/23/2017 Basic overview

CO2 O2 CO2 CO2 Lung Lung O2 O2 Heart O2-rich blood O2 O2-poor blood 4/23/2017 CO2 O2 CO2 CO2 Lung Lung O2 O2 Heart Figure 23.2 Double circulation O2-rich blood O2 O2-poor blood CO2 (a) Pulmonary circuit (b) Systemic circuit Figure 23.2

Animation: Path of Blood in Mammals 4/23/2017 One complete trip through the human cardiovascular system: Takes about one minute Requires two passes through the heart Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection). Animation: Path of Blood in Mammals

Capillaries of head, chest, and arms Superior vena cava Pulmonary 4/23/2017 Capillaries of head, chest, and arms Superior vena cava Pulmonary artery Pulmonary artery Aorta Capillaries of lung Capillaries of lung Pulmonary vein Pulmonary vein Right atrium Left atrium Figure 23.3 A trip through the human cardiovascular system (Step 11) Right ventricle Left ventricle Inferior vena cava Capillaries of abdominal region and legs O2-rich blood O2-poor blood Figure 23.3-11

To body O2-rich blood From body O2-poor blood Right lung Left lung 4/23/2017 To body O2-rich blood From body O2-poor blood Right lung Left lung Right atrium Left atrium Valves Valves Figure 23.4 Path of blood flow through the human heart Right ventricle Left ventricle From body Figure 23.4

Blast Animation: Cardiac Cycle Overview 4/23/2017 The Cardiac Cycle The heart relaxes and contracts throughout our lives. Diastole is the relaxation phase of the heart cycle. Systole is the contraction phase. Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection). Blast Animation: Cardiac Cycle Overview

Figure 23.5-3 Atria contract. Blood is forced into ventricles. 4/23/2017 Atria contract. Blood is forced into ventricles. Heart is relaxed. Blood flows in. 0.1 sec Diastole 0.8 sec 0.3 sec Systole 0.4 sec Figure 23.5 The cardiac cycle (Step 3) Ventricles contract. Blood is pumped out. Figure 23.5-3

The Pacemaker and the Control of Heart Rate 4/23/2017 The Pacemaker and the Control of Heart Rate The pacemaker, or SA (sinoatrial) node: Sets the tempo of the heartbeat Is composed of specialized muscle tissue in the wall of the right atrium Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection). Blast Animation: Electrical Coordination of the Cardiac Cycle

Figure 23.6 Wire leading to SA node Heart Artificial pacemaker 4/23/2017 Wire leading to SA node Heart Artificial pacemaker Pacemaker (SA node) AV node Right atrium Right ventricle Pacemaker generates electrical impulses. Impulses spread through atria. Impulses reach ventricles. Figure 23.6 Pacemakers (a) The heart’s natural pacemaker (b) Artificial pacemaker Figure 23.6

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4/23/2017 Blood Vessels If the heart is the body’s “pump,” then the “plumbing” is the system of arteries, veins, and capillaries. Arteries carry blood away from the heart. Veins carry blood toward the heart. Capillaries allow for exchange between the bloodstream and tissue cells. Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection).

Blood Flow through Arteries 4/23/2017 Blood Flow through Arteries The force that blood exerts against the walls of blood vessels is blood pressure. Blood pressure is the main force driving the blood from the heart to the capillary beds. A pulse is the rhythmic stretching of the arteries caused by the pressure of blood forced into the arteries during systole. Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection).

From heart To heart Epithelium Valve Epithelium Epithelium Smooth 4/23/2017 From heart To heart Epithelium Valve Epithelium Epithelium Smooth muscle Smooth muscle Connective tissue Connective tissue Artery Vein Figure 23.8 The structure of blood vessels Arteriole Venule Capillary Figure 23.8

Figure 23.9 Capillary Tissue cell Red blood cell Diffusion of 4/23/2017 Capillary Tissue cell Red blood cell Diffusion of O2 and nutrients out of capillary and into tissue cells Diffusion of CO2 and wastes out of tissue cells and into capillary From artery To vein Interstitial fluid Figure 23.9 Chemical exchange between the blood and tissue cells LM To vein (a) Capillaries (b) Chemical exchange Figure 23.9

Blood Flow through Capillary Beds 4/23/2017 Blood Flow through Capillary Beds At any given time, only about 5–10% of the capillaries have a steady flow of blood. The regulation of blood flow through capillaries Is controlled by muscles Reflects shifting demands by organs of the body Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection).

Capillaries The walls of capillaries are thin and leaky. 4/23/2017 Capillaries The walls of capillaries are thin and leaky. At the arterial end of the capillary, blood pressure pushes fluid rich in oxygen, nutrients, and other substances into the interstitial fluid. At the venous end of the capillary CO2 and other wastes diffuse from tissue cells into the capillary bloodstream. Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection).

Blood Flow in Capillary

Blood moves back towards the heart because of: 4/23/2017 Blood moves back towards the heart because of: Surrounding skeletal muscles that compress the veins One-way valves that permit blood flow only toward the heart Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection).

Blood An adult human has about 5 L (11 pints) of blood. 4/23/2017 Blood An adult human has about 5 L (11 pints) of blood. By volume, blood is about: 45% cells and 55% plasma, consisting of about: 90% water 10% dissolved salts, proteins, and other molecules Student Misconceptions and Concerns 1. Students often develop an incorrect “mental model” of how atherosclerosis occurs. In a home, drainpipes grow narrower as materials accumulate on the inside surface. However, in atherosclerosis, the blood vessels narrow by an accumulation of materials within the walls. 2. Students often do not make the connection between iron in blood and iron used to build ships, automobiles, and buildings. Some of this confusion results from other similar names that indeed are not the same material (lead in pencils is not lead!). So, be sure to note that iron in blood is the same iron that forms rust on our cars and buildings in our cities. 3. Students often expect that the blood flowing through the heart supplies the heart muscle with oxygen. The need for coronary arteries and veins is not clear. The thickness of the walls of the heart do not permit efficient diffusion. Further, the oxygen content of blood in the right atrium and right ventricle is unlikely to meet this need. 4. Students often struggle to explain how blood is propelled up their legs to return to their hearts (perhaps as they sit during class). Frequently, students will suggest that the heart itself provides sufficient force to move blood completely around the body. However, if such pressures were generated, delicate capillaries would be destroyed. Other student hypotheses might include a negative, siphoning effect of the heart. (Although this can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thought and motivation to learn the answer. After completing the explanation, you might also note that it has been suggested that students will be more alert in class if they wiggle their legs. Challenge students to explain why this might work and why “locking the knees” when standing might have the opposite effect. Teaching Tips 1. When discussing mammalian and avian blood flow through four-chambered hearts, it is helpful to remind students that the heart is essentially two pumps. The right side collects from the body and propels to the lungs; the left side propels from the lungs out to the body. Reminding them that the sequence is right to left helps them to recall the correct atrial and ventricular sequences. 2. You may point out that in artwork, it is common to identify blood vessels in the arterial system as red and blood vessels in the venous system as blue. As biologists, such expectations can be so routine that we forget that we might need to point this out to our students. 3. Students often benefit from a quick connection between abstract ideas and a concrete example. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class. Simply counting the beats in 15 seconds and multiplying by four will help them relate the lecture directly to themselves. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 4. If you had the students take their own pulses, this might be a good time to stimulate their curiosity. Students could be encouraged to learn more about how their heart rates vary during a day by comparing their pulse upon arrival to class versus in the middle of class (to compare the effects of exercise) and, if they consume caffeinated beverages, before and after consumption. 5. Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen poor blood, the pulmonary artery transports low oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or towards the heart). The structure of arteries better resists the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant. 6. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty, simply by lifting up the hands to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students. 7. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand”, students might better understand the propulsive forces moving venous blood back to the heart. 8. Students might wonder why they are discouraged from swimming soon after eating a meal. As the authors point out, blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming on a full stomach is that even a small amount of vomit could clog an air passageway. 9. If you have a small fiber-optic lamp available, it is interesting to shine the light on your fingertips in a darkened room and see your fingers glow red. It is a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies. 10. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, consider consulting human anatomy and physiology textbooks. Searching the American Heart Association website at www.americanheart.org and using the key word aspirin will generate many current and related articles. 11. Cardiovascular disease does not only affect the blood vessels of the heart and brain. Many of the same risk factors that promote cardiovascular disease are associated with erectile dysfunction (the inability to get and keep an erection).

Figure 23.11 Plasma (55%) Cellular elements (45%) Red blood cells 4/23/2017 Plasma (55%) Cellular elements (45%) Red blood cells (erythrocytes) Water (90% of plasma) Proteins Blood Dissolved salts (such as sodium, potassium, calcium) White blood cells (leukocytes) Figure 23.11 The composition of human blood Substances being transported (such as O2, CO2, nutrients, wastes, hormones) Platelets Figure 23.11

Blood Cells Red blood cells (erythrocytes) Contain hemoglobin Rapidly transport oxygen (and carbon dioxide) Have no nucleus when mature White blood cells (leukocytes) Tissue maintenance and repair Defenses against pathogens

Red Blood Cells ABOUT 99% OF ALL BLOOD CELLS 4/23/2017 Red Blood Cells ABOUT 99% OF ALL BLOOD CELLS FUNCTION TO TRANSPORT OXYGEN AND CARBON DIOXIDE PICK UP IN LUNGS DELIVER TO ALL CELLS CONTAIN IRON RICH PROTEIN HEMOGLOBIN MADE IN BONE MARROW CONTINUOUSLY Fig. 34.6, p. 558

Red Blood Cells CIRCULATE FOR ABOUT 120 DAYS THEN ARE BROKEN DOWN 4/23/2017 Red Blood Cells CIRCULATE FOR ABOUT 120 DAYS THEN ARE BROKEN DOWN CAN’T REPLICATE - THEY HAVE NO NUCLEUS ARE MADE IN THE BONE MARROW RBC in capillary

Platelets Platelets function in blood clotting Platelets and all blood cells arise from stem cells in bone marrow

White Blood Cells LEUKOCYTES - 1% OF BLOOD CELLS 4/23/2017 White Blood Cells LEUKOCYTES - 1% OF BLOOD CELLS NORMAL BLOOD -ABOUT 10,000 CELLS/MM3 MAKE IN THE BONE MARROW ARE NUCLEATED HELP BODY DEFEND AGAINST INVADERS LEUKEMIA CANCER OF WHITE BLOOD CELLS

WBC 5 KINDS OF WHITE BLOOD CELLS 4/23/2017 WBC 5 KINDS OF WHITE BLOOD CELLS NEUTROPHILS-PHAGOCYTOSIS AND PROCESSING LYMPHOCYTES- IMMUNITY MONOCYTES-GIVE RISE TO MACROPHAGES EOSINOPILS- ASSOCIATED WITH ALLERGIES BASOPHILS-INTENSIFY INFLAMMATION

Blood Platelets FRAGMENTS OF CELLS FUNCTION IN CONTROLLING BLEEDING 4/23/2017 Blood Platelets FRAGMENTS OF CELLS FUNCTION IN CONTROLLING BLEEDING FORMED IN THE BONE MARROW

(bits of membrane-enclosed cytoplasm that aid clotting) 4/23/2017 Platelets (bits of membrane-enclosed cytoplasm that aid clotting) Colorized SEM Fibrin Figure 23.12c The three cellular components of blood: platelets Colorized SEM Red blood cell Figure 23.12c

ABO Blood Typing Helps match blood of donors and recipients to avoid blood transfusion problems (agglutination)

Rh Blood Typing Helps prevent problems that may arise when maternal and fetal Rh blood types differ

Circulatory System Disorders Atherosclerosis, hypertension (chronic high blood pressure), heart attacks, strokes, certain arrhythmias Regular exercise, maintaining normal body weight, and not smoking lower risk for these disorders

Artery partially blocked by plaque 4/23/2017 Plaque Connective tissue Smooth muscle Epithelium Figure 23.14 A normal artery and an artery showing atherosclerosis Normal artery Artery partially blocked by plaque Figure 23.14

Aorta Coronary artery (supplies oxygen to the heart muscle) 4/23/2017 Aorta Coronary artery (supplies oxygen to the heart muscle) Figure 23.13 Blockage of a coronary artery, resulting in a heart attack Dead muscle tissue Blockage Figure 23.13