Chapter Summary: The Cardiovascular System
The Cardiovascular System
CHAPTER SUMMARY
The importance of the cardiovascular system cannot be overstated. This is one system that students frequently know something about, at least from a plumbing viewpoint, but they often don’t completely understand the complexity of the system and the magnitude of its tasks. An essential component of presentation of the material is then to outline in detail the role of the cardiovascular system and its significance to all other body systems.
This chapter begins with the fundamental information about the heart by first discussing anatomy and then moving on to the more complex physiology. The section on anatomy covers the layers of the heart as well as its chambers, valves, and the vessels through which …show more content…
blood moves in and out of its various regions. A section on cardiac circulation explains the way the heart itself is supplied with oxygen-rich blood.
The structural and mechanical characteristics of the heart are followed by a discussion of its unique electrical intrinsic activity. The conduction system is outlined and relevant homeostatic imbalances are discussed. Concepts related to the electrical conduction system of the heart are always difficult to grasp, and key demonstrations and activities help solidify the students’ understanding.
Following the section on the heart itself is the portion of the chapter dealing with the blood vessels. Arteries, veins, and capillaries are compared for their structural and physiological similarities as well as their differences. Names of the major vessels are given, as the route of blood is traced from its point of exit from the heart through the aorta to all parts of the body and back to the heart via the superior and inferior venae cavae. A look into the various mechanisms involved in blood pressure precedes a discussion of the special circulatory routes that supply the brain, liver, and developing fetus. Finally, the developmental aspects of circulation are considered.
SUGGESTED LECTURE OUTLINE I. THE HEART (pp. 362–374) A. Anatomy of the Heart (pp. 362–368) 1. Location and Size 2. Coverings and Wall 3. Chambers and Associated Great Vessels a. Atria b. Ventricles c. Superior and Inferior Venae Cavae d. Pulmonary Arteries e. Pulmonary Veins f. Aorta 4. Valves a. Atrioventricular (AV) Valves b. Semilunar Valves 5. Cardiac Circulation 6. Homeostatic Imbalances a. Endocarditis b. Angina Pectoris c. Myocardial Infarction B. Physiology of the Heart (pp. 368–374) 1. Intrinsic Conduction System of the Heart: Setting the Basic Rhythm a. Intrinsic Conduction System b. Homeostatic Imbalances i. Heart Block ii. Ischemia iii. Fibrillation 2. Cardiac Cycle and Heart Sounds a. Mid-to-Late Diastole b. Ventricular Systole c. Early Diastole d. Homeostatic Imbalances i. Murmurs 3. Cardiac Output (CO) a. Regulation of Stroke Volume (SV) b. Factors Modifying Basic Heart Rate (HR) c. Neural (ANS) Controls d. Physical Factors e. Homeostatic Imbalanaces i. Congestive Heart Failure (CHF) ii. Pulmonary Edema II. BLOOD VESSELS (pp. 374–395) A. Microscopic Anatomy of Blood Vessels (pp. 374–377) 1. Tunics 2. Structural Differences between Arteries, Veins, and Capillaries 3. Homeostatic Imbalanaces a. Varicose Veins b. Thrombophlebitis c. Pulmonary Embolism B. Gross Anatomy of Blood Vessels (pp. 378–386) 1. Major Arteries of the Systemic Circulation (Figure 11.12) a. Arterial Branches of the Ascending Aorta i. Right and Left Coronary Arteries b. Arterial Branches of the Aortic Arch i. Brachiocephalic Trunk ii. Left Common Carotid Artery iii. Left Subclavian Artery c. Arterial Branches of the Thoracic Aorta i. Intercostal Arteries ii. Bronchial Arteries iii. Esophageal Arteries iv. Phrenic Arteries d. Arterial Branches of the Abdominal Aorta i. Celiac Trunk ii. Superior Mesenteric Artery iii. Renal Arteries iv. Gonadal Arteries v. Lumbar Arteries vi. Inferior Mesenteric Artery vii. Common Iliac Arteries 2. Major Veins of the Systemic Circulation (Figure 11.13) a. Veins Draining into the Superior Vena Cava i. Radial and Ulnar Veins ii. Cephalic Vein iii. Basilic Vein iv. Subclavian Vein v. Vertebral Vein vi. Internal Jugular Vein vii. Brachiocephalic Vein viii. Azygos Vein b. Veins Draining into the Inferior Vena Cava i. Anterior and Posterior Tibial Veins and Fibular Vein ii. Great Saphenous Veins iii. Common Iliac Veins iv. Gonadal Veins v. Renal Veins vi. Hepatic Portal Vein vii. Hepatic veins 3. Special Circulations (Figures 11.14–11.17) a. Arterial Supply of the Brain and the Circle of Willis b. Fetal Circulation c. Hepatic Portal Circulation C. Physiology of Circulation (pp. 387–395) 1. Arterial Pulse 2. Blood Pressure a. Blood Pressure Gradient b. Measuring Blood Pressure c. Effects of Various Factors on Blood Pressure i. Neural Factors: The Autonomic Nervous System ii. Renal Factors: The Kidneys iii. Temperature iv. Chemicals v. Diet d. Variations in Blood Pressure 3. Capillary Exchange of Gases and Nutrients 4. Fluid Movements at Capillary Beds III. DEVELOPMENTAL ASPECTS OF THE CARDIOVASCULAR SYSTEM (pp. 395, 397) A. Embryonic Development B. Congenital Heart Defects C. Exercise D. Coronary Artery Disease
KEY TERMS aorta aortic arch aortic semilunar valve arteries arterioles ascending aorta atria atrioventricular (AV) node bicuspid (mitral) valve blood pressure brachial vein bradycardia bundle branches cardiac output (CO) cardiac veins cardiovascular system chordae tendineae common carotid artery common hepatic artery coronary arteries coronary artery disease coronary sinus diastolic pressure ductus arteriosus ductus venosus endocardium epicardium femoral artery femoral vein pericardium gastric vein great saphenous vein heart rate (HR) heart sounds hepatic portal vein hepatic veins high blood pressure hypertension hypotension inferior vena cava internal carotid arteries internal jugular vein interstitial fluid (tissue fluid) marginal arteries median cubital vein mediastinum myocardium pacemaker pressure points pulmonary arteries pulmonary circulation pulmonary semilunar valve pulmonary veins pulse Purkinje fibers radial artery radial vein renal arteries renal veins right and left coronary arteries semilunar valves sinoatrial (SA) node subclavian artery subclavian vein superior vena cava systemic circulation systole systolic pressure tachycardia thoracic aorta tricuspid valve valves vascular system vasoconstriction veins ventricles vital signs
LECTURE HINTS 1. Descriptively present the cardiovascular system as the great transportation system of the body, similar to a mail delivery system, that not only carries the oxygen and carbon dioxide people usually relate to it, but also delivers nutrients, removes toxic wastes, conveys heat, and transports the myriad of hormones that are essential to all regulatory functions. Key point: Drawing an analogy between the cardiovascular system and a mail delivery system helps students conceptualize the work of this intricate system. 2. Although the left side of the heart generates more pressure than the right side, approximately the same volume of blood is ejected from each side per beat. Ask students to think about what would happen if this were not the case. Follow up with a discussion on congestive heart failure. Key point: In CHF, blood pumped to the lungs by the right ventricle does not keep pace with blood pumped around the system by the left ventricle. Fluid builds up in the lungs, leading to the predominant symptom of CHF, which is breathing difficulty. 3. Students may recall that the average blood volume of a healthy adult male is 5–6 liters. All blood generally circulates completely through the body in about one minute while at rest. Key point: 5–6 liters/minute is the average resting cardiac output for an average healthy adult male. 4. Compare the body’s self-regulating pacemaker, the SA node, to an artificial pacemaker in function and performance. Describe the 1,000,000 or more times each week that the heart’s pacemaker fires and causes it to pump blood around the system and back again to the heart. Key point: Students are usually quite surprised to learn that humans have a built-in pacemaker that is actually much more efficient, longer lasting, and more versatile than an artificial one. 5.
Stress that the only function of the valves of the heart is to ensure the one-way flow of blood. Explore with the students the consequences of incompetent or stenotic valves. Key point: This provides an opportunity to differentiate between the various types of murmurs and their etiology. 6. Discuss the chordae tendineae, or “heart strings.” Explain their function as similar to the stays of an umbrella, designed to keep the heart valves from turning inside out under extreme pressure. Key point: The reference to something “tugging at their heart strings” gives students a concrete example of the way in which anatomy, particularly of the heart, has an established place in our language and literature. 7. Outline the remarkable engineering involved in the design of the blood vessels, which allows them to absorb the pressure emitted from the heart with each beat and to return blood back to the heart, usually on an uphill course against the constant pull of gravity. Key point: In differentiating between arteries, veins, and capillaries, emphasize that the structure of each type of vessel is related to the differing amounts of pressure they must each absorb from the heart, as well as their respective roles in blood …show more content…
transport. 8. A basic misconception students have is that arteries carry oxygenated blood and veins carry deoxygenated blood. While this is usually true, the heart is a notable exception. Remind students that arteries are defined as vessels that carry blood away from the heart and veins carry blood toward the heart. Key point: The pulmonary arteries carry deoxygenated blood from the right side of the heart to the lungs, and the pulmonary veins return oxygenated blood to the left side of the heart. 9. Veins are more superficial and are occluded when a phlebotomist applies a tourniquet that enables veins to rise as blood is still being pumped distally through arteries running underneath the tourniquet. Key point: Veins are low pressure vessels and need less strength, support, and elasticity than the arteries. 10. In discussing fetal circulation, point out that all fetuses have a “hole in their heart,” and in fact two holes, which allow circulation to be routed around the non-inflated lungs. Explain the fact that if these “holes” don’t close at or shortly after birth, then surgical closure is required, usually to correct a PDA (patent ductus arteriosus). Key point: Again, this is an example of a linguistic reference that has an actual anatomic basis, which students find fascinating. 11. Discuss the blood supply to the heart itself, pointing out that despite the fact that blood fills all the chambers of the heart, the heart cannot nourish itself from the inside. Explain coronary artery disease (CAD) and its common sequelae, the coronary artery bypass graft (known as CABG and pronounced “cabbage”). Key point: It is important for students to recognize that the heart must be infiltrated with its own vascular supply in order to receive the oxygen and nutrients necessary for its survival. Any blockage in the vascular flow will lead to tissue damage, resulting in a myocardial infarction or “heart attack.” Note the difference between open heart surgery (valve replacement, etc.) and open chest surgery (CABG). 12. Differentiate between atherosclerosis and arteriosclerosis, pointing out that “athero” means yellow, fatty plaque, and discuss the role of cholesterol in its development. Point out that there is no such thing as “good” and “bad” cholesterol, and that we actually need both types within our bodies for transportation purposes. Explain that it is simply a matter of ratio, or the proportion of low-density lipids to high. Key point: This is a good time to dispel the notion of good and bad cholesterol, and instead to help students understand that moderation is key to a healthy cardiovascular system. Point out that the lymphatic system dumps fats into the vena cavae immediately before blood returns to the heart. 13. Describe the various methods that can be used to treat atherosclerosis (e.g., stents, angioplasty). Key point: Students are generally familiar with the concept of blocked blood vessels, but are often unaware of treatments other than bypass surgery. 14. Discuss Olestra, the fat substitute, and its physiological effects on the body, including the blood vessels. Key point: Through advertising, students are usually quite familiar with nutritional substitutes, such as fat and sugar substitutes, but they often don’t understand the mechanisms at play and the potential side effects from the use of these substitutes. 15. Discuss smoking and its cardiovascular implications, including arteriovascular insufficiency, ischemia, intermittent claudication with concomitant leg pain and cramps, thrombus formation, and impotence. Key point: The impact of smoking on the cardiovascular system is so significant that it is important to incorporate a discussion of the smoking-related disorders into the class presentation. 16. Present information on deep vein thrombi (DVTs) and their incidence related to bed rest and/or a sedentary lifestyle. Explain their connection to long distance travel, birth control pills, and genetics. Point out the irony that the treatment for DVTs includes bed rest along with anticoagulant medication. Key point: This discussion helps students gain perspective on potential serious homeostatic imbalances of the venous system and their causes. 17. Discuss the correlation of Group A streptococcal infections such as “strep throat” to rheumatic fever and rheumatic heart disease, which can lead to mitral valve damage. Key point: Students are usually familiar with the illness described as “strep throat,” but often are unaware of its serious ramifications. 18. Explain the etiology and pathology associated with hypertension, along with methods of prevention and treatment options. Key point: Since hypertension is one of the major risk factors in coronary artery disease, stroke, congestive heart failure, and kidney failure, presentation of the causative factors and current thinking on prevention and treatment are important concepts for students to understand. Excessive salt in the diet retains more fluid within the vessels and thus increases blood pressure internally, as compared to external stressors that increase blood pressure externally. 19. Explain that the intrinsic electrical conduction can be picked by ECG electrodes placed anywhere on the external skin surface. Key point: Electrical activity goes from the body to the machine and heart paddles placed on an emergency patient are designed to stop the heart and hopefully enable normal autorhythmicity to take over. Explain that a rescuer would not want to give a patient just pulled out of a swimming pool several hundred joules of energy if the deck is not dry. 20. Differentiate between myocardial infarction, stroke, pulmonary embolism, and thrombi. Key point: Students often do not realize that these terms can all be related to one another since they refer to blockage of blood vessels in different parts of the body. 21. Explain the difference between an aneurysm and a ruptured aneurysm. Key point: The media often does not distinguish between these two terms, so students can get confused as to their effects and treatment. 22. Describe all of the different physical, chemical, and neurological factors that can modify heart rate. Key point: Explain to students that a wide variety of factors located all over the body can play a role in determining heart rate.
CLASSROOM DEMONSTRATIONS AND STUDENT ACTIVITIES
Classroom Demonstrations: 1. Film(s) or other media of choice. 2. Show a video of a beating heart, ideally with heart sounds. Stress that while the right side of the heart is a pulmonary pump and the left side a systemic pump, both atria contract at the same time and both ventricles contract at the same time. 3. Use a dissectible heart model to show heart structure. 4. Use a dissectible human torso model to point out the major arteries and veins of the body. 5. Show the chordae tendineae, the “heart strings,” on a dissected heart. 6. Show a chart of various types and grades of heart murmurs, explaining that some of them are considered nonpathological and are merely “functional” (related to low fluid volume, etc.). 7. Play a recording of normal and abnormal heart sounds to accompany your presentation of valve function and malfunction. (Interpreting Heart Sounds is available for loan from local chapters of the American Heart Association.) 8. Demonstrate the recording of an
ECG. 9. Bring in a test tube or show pictures of blood in a test tube containing high fat content. Point out that at times the fat content is so high, you can actually see floating clumps of fat in the specimen. 10. Have a guest speaker from the American Heart Association talk to the class about the risk factors and leading causes of heart disease. 11. Bring in an old mechanical pacemaker and show its placement on the chest wall under the skin. Compare the heart’s own pacemaker, the SA node, to the implanted mechanical device, explaining that artificial pacemakers keep a set pulse rate and are not regulated by increased or decreased activity. 12. Demonstrate the use of defibrillators, including AEDs, and explain their function in cardiac rescue. Also discuss CPR as it relates to heart function. 13. Show pictures of and describe “pitting” edema. Explain how fluid can fill the interstitial spaces to such a degree that an indentation will stay when the skin is pressed with the index finger. 14. Obtain synthetic bypass graft material and compare it in use and effectiveness to the preferred saphenous vein. 15. Describe the different symptoms of impending myocardial infarction (heart attack) in men and women. Provide statistics showing the increase in diagnosis of MI in women. 16. Show a video of a heart operation and the importance of a perfusionist, who assists the heart surgeon. 17. Have a phlebotomist speak to the class about locations to draw blood in children and in adults. Have the speaker explain the difficulties in drawing blood when the patient is obese or dehydrated, and the methods they use during those situations.
Student Activities: 1. Demonstrate how apical and radial pulses are taken, and have students practice on each other. 2. Demonstrate the location of the radial, brachial, carotid, femoral, popliteal, and pedal pulses. Have students locate several of their own and compare their rate and rhythm. Discuss the clinical implications of weak or absent pulses in the extremities. 3. Demonstrate the auscultatory method of taking blood pressure and provide sphygmomanometers and stethoscopes for students to practice on each other. 4. Ask students to bring in a daily record of their blood pressure in the upright and supine positions for a specified period of time to chart and compare. 5. Provide simple drawings of a dissected heart and have the students follow the path of blood as it flows through the various chambers. Ask them to use red and blue pencils to differentiate between oxygenated and deoxygenated blood. Also ask them to label the chambers, valves, septa, and other distinguishing features. 6. Have students run in place or do jumping jacks for 3 minutes, then have them record their radial pulse (pointing out that a radial pulse is always thumb side). Have them continue to take their pulse every 30 seconds for 5 minutes, then graph the results. Point out that a steep decline in the first minute or so indicates rapid recovery by the heart. 7. Provide the students with a diagram of the major blood vessels for labeling. 8. Have students record their salt intake for one week. Provide them with a chart showing salt content in foods and also review the use of food labels. Have them graph their daily salt intake and compare it to the FDA limit. Discuss which foods, like milk products and pickles, are surprisingly high in salt content. 9. Encourage students to obtain CPR training and offer extra credit for documentation of certification during the semester. 10. Have students plan an investigation to learn more about heart rate and heart sounds. Have them select a problem, such as the relationship of age or weight, and determine its effect on heart rate and heart sounds. Have them formulate a testable hypothesis and list the steps for the investigation, including the selection of appropriate equipment and technology. They should implement the investigation, record the data in a chart, and draw conclusions from that data. 11. Have students plan an investigation to determine the effect of time of day on a selected vital sign. They should formulate a testable hypothesis and list the steps in the investigation to test this hypothesis, including the equipment and technology that would be used. With your approval, students should then implement their plan using their classmates as subjects. They should record the data and draw conclusions about the effect of time of day on the selected vital sign. 12. Have your students answer the following question to demonstrate their understanding of how to select appropriate equipment and technology: Mr. Wright is working in his garden. Suddenly he experiences tightness across his chest and knows this is not a good sign. He uses his cell phone to call 911, and rests until the ambulance arrives. The EMT will assess his condition and put electrodes across his chest to measure his heart action. What is the name of this medical equipment? A. Electrocardiograph* B. IV C. Thermometer D. Ophthalmoscope 13. Have a student perform an incremental stationary bicycle test and record heart rate and blood pressure from rest to exhaustion. Note how systolic blood pressure increases at higher exercise workloads and diastolic blood pressure remains nearly the same (important because diastole is when the heart is able to feed itself). 14. Where possible, bring students to a teaching hospital to observe open heart surgery and/or heart transplantation. 15. Have students dissect a cow’s heart both sagittally and transversely to observe the differences in valves, chambers, wall thickness, and right/left sides.
ANSWERS TO END OF CHAPTER REVIEW QUESTIONS
Questions appear on pp. 399–401
Multiple Choice 1. d (Figure 11.3) 2. b (p. 372) 3. d (p. 368; Figure 11.6) 4. a, c (pp. 369–371) 5. c (p. 370) 6. a, c (p. 371) 7. b (p. 362) 8. a, c (p. 374; Figure 11.9) 9. d (p. 378; Figure 11.12) 10. a (Figure 11.12) 11. b (p. 383) 12. a, c, d (pp. 378, 380) 13. b (pp. 392–393) 14. a, b, c (p. 397) 15. c (pp. 372–373) 16. b (p. 362) 17. d (pp. 365–366; Figure 11.2d) 18. b (p. 366; Figure 11.2d) 19. b (pp. 363–364; Figure 11.2b)
SHORT ANSWER ESSAY 20. See Figure 11.2. (pp. 363–364) 21. Right atrium to right ventricle to pulmonary trunk to right and left pulmonary arteries to pulmonary capillaries of the lungs to right and left pulmonary veins to left atrium of the heart. Pulmonary circuit or pulmonary circulation. (p. 365; Figure 11.3) 22. The pericardial (serous) fluid acts as a lubricant to decrease friction as the heart beats. (p. 363) 23. Systole: Period of contraction of the heart (usually refers to ventricular contraction). Diastole: Period of relaxation of the heart musculature. Stroke volume: The amount of blood pumped out by a ventricle with each contraction. Cardiac cycle: The time for one complete heartbeat, from the beginning of one systole to the beginning of the next. (pp. 369, 372) 24. The heart has an intrinsic ability to beat (contract), which is different from all other muscles in the body. Whereas the nervous system may increase or decrease its rate, the heart continues to beat even if all nervous connections are cut. (p. 368) 25. SA node (pacemaker), AV node, AV bundle (bundle of His), bundle branches, Purkinje fibers. (p. 368) 26. Activity of the sympathetic nervous system (as during physical or emotional stress), excess or lack of certain vital ions, increased temperature, hormones (epinephrine, thyroxine), sudden drop in blood volume, age, gender, and exercise. (p. 368) 27. Tunica intima: A single layer of squamous epithelium; provides a smooth, friction-reducing lining for the vessel. Tunica media: A middle layer, consisting of smooth muscle and connective tissue (primarily elastic fibers). The elastic fibers provide for stretching and then passive recoil of vessels close to the heart, which are subjected to pressure fluctuations; the smooth muscle is activated by the sympathetic nervous system when vasoconstriction (and increases in blood pressure) is desired. Tunica externa: The outermost layer, made of fibrous connective tissue; basically a protective and supporting layer. (pp. 374–376) 28. Capillary walls are essentially just the tunica intima (endothelium plus the basement membrane); thus, they are exceedingly thin. (p. 376) 29. Arteries are much closer to the pumping action of the heart and must be able to withstand the pressure fluctuations at such locations. Veins, on the distal side of the capillary beds of the tissues, are essentially low-pressure vessels that need less strength/support/ elasticity than do arteries. (p. 376) 30. The presence of valves, the milking action of skeletal muscles against the veins as the muscles contract, the respiratory pump (pressure changes in the thorax during breathing). (p. 376) 31. Pulmonary arteries carry oxygen-poor blood and pulmonary veins carry oxygen-rich blood. Umbilical arteries carry oxygen-poor blood from the fetus and the umbilical vein carries the most oxygen-rich blood to the fetus. (pp. 365, 383–384) 32. Right wrist: Left ventricle to ascending aorta to aortic arch to brachiocephalic artery to subclavian artery to axillary artery to brachial artery to radial (or ulnar) artery to capillary network of wrist to radial (or ulnar) vein to brachial vein to axillary vein to subclavian vein to right brachiocephalic vein to superior vena cava to right atrium of the heart. Right foot: Left ventricle to ascending aorta to aortic arch to descending aorta to right common iliac artery to external iliac artery to femoral artery to popliteal artery to anterior tibial artery to dorsalis pedis artery to capillary network to anterior tibial vein to popliteal vein to femoral vein to external iliac vein to common iliac vein to inferior vena cava to right atrium of the heart. (Alternatively, the sequence between the capillary network and external iliac vein could be stated as: dorsal venous arch to great saphenous vein.) (Figures 11.12–11.13) 33. The hepatic portal circulation carries nutrient-rich blood from the digestive viscera to the liver for processing before the blood enters the systemic circulation. A portal circulation involves a capillary bed that is both fed and drained by veins; the usual circulation has a capillary bed that is fed by arteries and drained by veins. (pp. 385–386) 34. In a fetus, both liver and lungs are nonfunctional (the liver relatively so). The ductus venosus bypasses the liver. The ductus arteriosus and the foramen ovale bypass the lungs. The umbilical vein carries nutrient-rich and oxygen-rich blood to the fetus through the umbilical cord. (pp. 383–385) 35. Pulse: The alternate expansion and recoil of an artery that occur with each heartbeat. (p. 387) 36. Front of the ear: Temporal artery. Back of knee: Popliteal artery. (p. 387; Figure 11.18) 37. Systolic pressure: Pressure exerted by blood on the arterial walls during ventricular contraction. Diastolic pressure: Pressure exerted by blood on the arterial walls when the ventricles are relaxing (that is, during diastole). (p. 388) 38. Cardiac output is increased by increased venous return and increased heart rate. Peripheral resistance is increased by decreased diameter of the blood vessels and increased blood viscosity. (Figure 11.21) 39. Blood pressure is normally highest in the recumbent position and lowest immediately after standing up; however, the sympathetic nervous system quickly compensates in a healthy individual. Very often an individual can become hypotensive after remaining still in the sitting position for an extended period. (pp. 389–390) 40. Intercellular clefts allow limited passage of solutes and fluid. Fenestrated capillaries allow very free passage of small solutes and fluids. Capillaries lacking these modifications are relatively impermeable. (p. 394) 41. Veins that have become twisted and dilated because of incompetent valves. Inactivity (lack of skeletal milking activity against the veins), which allows the blood to pool in the lower extremities; increased pressure that restricts venous return (as in pregnancy and obesity). (p. 377, 397) 42. Blood flow in arteries is pulsatile because it is under a greater amount of pressure compared to veins. Arteries are located closer to the ventricles, so their walls must be capable of expanding and contracting under the changes in pressure when the ventricles contract. When blood reaches the veins, the pressure is very low, and so instead of veins having a pulsatile ability to maintain pressure, they instead have valves to prevent backflow. (pp. 387–388) 43. The greater the cross-sectional area in a blood vessel, the faster that blood can flow through that vessel. Smaller vessels, like capillaries, are only one cell thick in diameter, which slows down blood flow and allows nutrient and gas exchange to occur. (p. 374) 44. Arterioles are the blood vessels that are most important in regulating vascular resistance. These vessels can constrict as a result of activity from the sympathetic nervous system, which alters blood pressure. Atherosclerosis in these vessels also causes narrowing due to plaque deposits, which also affects blood pressure. (p. 388)
ANSWERS TO CRITICAL THINKING AND CLINICAL APPLICATION QUESTIONS 45. Hypertension: abnormally elevated or high blood pressure (generally described as systolic pressure consistently over 140 mm Hg and diastolic pressure consistently over 90 mm Hg in younger adults). (pp. 391, 394) Arteriosclerosis: “hardening of the arteries,” the result of deposit of fatty-cholesterol substances and calcium salts onto the inner walls of the blood vessels. Arteriosclerosis can be a direct cause of hypertension because it decreases the elasticity of the arteries (thereby increasing peripheral resistance). (p. 393) Hypertension is often called the “silent killer” because it progresses initially (and often over a prolonged period) without obvious symptoms. Three lifestyle habits that might help prevent cardiovascular disease are regular exercise, a diet low in saturated fats and salt, and a decrease in stress. (Quitting smoking would also help.) 46. She has pulmonary edema. The right side of the heart is still sending blood to the lungs, but the left side of the heart, the systemic pump, is not pumping blood entering its chamber (from the pulmonary circuit) to the systemic circulation. As the pressure increases in the pulmonary vessels, they become leaky, and fluid enters the tissue spaces of the lungs. (p. 374) 47. Incompetence (not stenosis) of the pulmonary semilunar valve. Incompetent valves produce swishing sounds, and the pulmonary semilunar valve is heard at the superior left corner of the heart, as indicated in this question. (pp. 371–372) 48. The compensatory mechanisms of Mrs. Johnson include an increase in heart rate and an intense vasoconstriction, which allows blood in various blood reservoirs to be rapidly added to the major circulatory channels. (pp. 388–391; Figure 11.21) 49. The left atrium and the posterior portion of the left ventricle. (p. 367; Figure 11.2) 50. Chronically elevated due to increased blood volume. ADH promotes retention of water by the kidneys. (pp. 390–391; Figure 11.21) 51. Blood flow is increased to areas of need and decreased to areas of non-need due to constriction and dilation of arterioles as blood will flow down pathway of least resistance. Competition for blood flow between the GI tract, which needs more blood circulation for absorption, and the skeletal muscles, which simultaneously need more blood for exercise, will cause indigestion much more quickly than muscle cramping. (pp. 385, 389–390) 52. Standing erect for prolonged periods enables gravity to pool blood in lower extremities, particularly in the absence of muscle pump activity which increases venous return during movement. Reduction in venous return causes reductions in stroke volume, causing lightheadedness as blood flow to brain is reduced. Standing in a hot environment will also produce sweating, vasodilation, and a reduction of blood plasma, which further decreases stroke volume. (p. 376)
CLASSROOM DEMONSTRATIONS AND STUDENT ACTIVITIES
Classroom Demonstrations: 1. Film(s) or other media of choice. 2. Show a video of a beating heart, ideally with heart sounds. Stress that while the right side of the heart is a pulmonary pump and the left side a systemic pump, both atria contract at the same time and both ventricles contract at the same time. 3. Use a dissectible heart model to show heart structure. 4. Use a dissectible human torso model to point out the major arteries and veins of the body. 5. Show the chordae tendineae, the “heart strings,” on a dissected heart. 6. Show a chart of various types and grades of heart murmurs, explaining that some of them are considered nonpathological and are merely “functional” (related to low fluid volume, etc.). 7. Play a recording of normal and abnormal heart sounds to accompany your presentation of valve function and malfunction. (Interpreting Heart Sounds is available for loan from local chapters of the American Heart Association.) 8. Demonstrate the recording of an ECG. 9. Bring in a test tube or show pictures of blood in a test tube containing high fat content. Point out that at times the fat content is so high, you can actually see floating clumps of fat in the specimen. 10. Have a guest speaker from the American Heart Association talk to the class about the risk factors and leading causes of heart disease. 11. Bring in an old mechanical pacemaker and show its placement on the chest wall under the skin. Compare the heart’s own pacemaker, the SA node, to the implanted mechanical device, explaining that artificial pacemakers keep a set pulse rate and are not regulated by increased or decreased activity. 12. Demonstrate the use of defibrillators, including AEDs, and explain their function in cardiac rescue. Also discuss CPR as it relates to heart function. 13. Show pictures of and describe “pitting” edema. Explain how fluid can fill the interstitial spaces to such a degree that an indentation will stay when the skin is pressed with the index finger. 14. Obtain synthetic bypass graft material and compare it in use and effectiveness to the preferred saphenous vein. 15. Describe the different symptoms of impending myocardial infarction (heart attack) in men and women. Provide statistics showing the increase in diagnosis of MI in women. 16. Show a video of a heart operation and the importance of a perfusionist, who assists the heart surgeon. 17. Have a phlebotomist speak to the class about locations to draw blood in children and in adults. Have the speaker explain the difficulties in drawing blood when the patient is obese or dehydrated, and the methods they use during those situations.
Student Activities: 1. Demonstrate how apical and radial pulses are taken, and have students practice on each other. 2. Demonstrate the location of the radial, brachial, carotid, femoral, popliteal, and pedal pulses. Have students locate several of their own and compare their rate and rhythm. Discuss the clinical implications of weak or absent pulses in the extremities. 3. Demonstrate the auscultatory method of taking blood pressure and provide sphygmomanometers and stethoscopes for students to practice on each other. 4. Ask students to bring in a daily record of their blood pressure in the upright and supine positions for a specified period of time to chart and compare. 5. Provide simple drawings of a dissected heart and have the students follow the path of blood as it flows through the various chambers. Ask them to use red and blue pencils to differentiate between oxygenated and deoxygenated blood. Also ask them to label the chambers, valves, septa, and other distinguishing features. 6. Have students run in place or do jumping jacks for 3 minutes, then have them record their radial pulse (pointing out that a radial pulse is always thumb side). Have them continue to take their pulse every 30 seconds for 5 minutes, then graph the results. Point out that a steep decline in the first minute or so indicates rapid recovery by the heart. 7. Provide the students with a diagram of the major blood vessels for labeling. 8. Have students record their salt intake for one week. Provide them with a chart showing salt content in foods and also review the use of food labels. Have them graph their daily salt intake and compare it to the FDA limit. Discuss which foods, like milk products and pickles, are surprisingly high in salt content. 9. Encourage students to obtain CPR training and offer extra credit for documentation of certification during the semester. 10. Have students plan an investigation to learn more about heart rate and heart sounds. Have them select a problem, such as the relationship of age or weight, and determine its effect on heart rate and heart sounds. Have them formulate a testable hypothesis and list the steps for the investigation, including the selection of appropriate equipment and technology. They should implement the investigation, record the data in a chart, and draw conclusions from that data. 11. Have students plan an investigation to determine the effect of time of day on a selected vital sign. They should formulate a testable hypothesis and list the steps in the investigation to test this hypothesis, including the equipment and technology that would be used. With your approval, students should then implement their plan using their classmates as subjects. They should record the data and draw conclusions about the effect of time of day on the selected vital sign. 12. Have your students answer the following question to demonstrate their understanding of how to select appropriate equipment and technology: Mr. Wright is working in his garden. Suddenly he experiences tightness across his chest and knows this is not a good sign. He uses his cell phone to call 911, and rests until the ambulance arrives. The EMT will assess his condition and put electrodes across his chest to measure his heart action. What is the name of this medical equipment? A. Electrocardiograph* B. IV C. Thermometer D. Ophthalmoscope 13. Have a student perform an incremental stationary bicycle test and record heart rate and blood pressure from rest to exhaustion. Note how systolic blood pressure increases at higher exercise workloads and diastolic blood pressure remains nearly the same (important because diastole is when the heart is able to feed itself). 14. Where possible, bring students to a teaching hospital to observe open heart surgery and/or heart transplantation. 15. Have students dissect a cow’s heart both sagittally and transversely to observe the differences in valves, chambers, wall thickness, and right/left sides.
CHAPTER SUMMARY
The importance of the cardiovascular system cannot be overstated. This is one system that students frequently know something about, at least from a plumbing viewpoint, but they often don’t completely understand the complexity of the system and the magnitude of its tasks. An essential component of presentation of the material is then to outline in detail the role of the cardiovascular system and its significance to all other body systems.
This chapter begins with the fundamental information about the heart by first discussing anatomy and then moving on to the more complex physiology. The section on anatomy covers the layers of the heart as well as its chambers, valves, and the vessels through which …show more content…
blood moves in and out of its various regions. A section on cardiac circulation explains the way the heart itself is supplied with oxygen-rich blood.
The structural and mechanical characteristics of the heart are followed by a discussion of its unique electrical intrinsic activity. The conduction system is outlined and relevant homeostatic imbalances are discussed. Concepts related to the electrical conduction system of the heart are always difficult to grasp, and key demonstrations and activities help solidify the students’ understanding.
Following the section on the heart itself is the portion of the chapter dealing with the blood vessels. Arteries, veins, and capillaries are compared for their structural and physiological similarities as well as their differences. Names of the major vessels are given, as the route of blood is traced from its point of exit from the heart through the aorta to all parts of the body and back to the heart via the superior and inferior venae cavae. A look into the various mechanisms involved in blood pressure precedes a discussion of the special circulatory routes that supply the brain, liver, and developing fetus. Finally, the developmental aspects of circulation are considered.
SUGGESTED LECTURE OUTLINE I. THE HEART (pp. 362–374) A. Anatomy of the Heart (pp. 362–368) 1. Location and Size 2. Coverings and Wall 3. Chambers and Associated Great Vessels a. Atria b. Ventricles c. Superior and Inferior Venae Cavae d. Pulmonary Arteries e. Pulmonary Veins f. Aorta 4. Valves a. Atrioventricular (AV) Valves b. Semilunar Valves 5. Cardiac Circulation 6. Homeostatic Imbalances a. Endocarditis b. Angina Pectoris c. Myocardial Infarction B. Physiology of the Heart (pp. 368–374) 1. Intrinsic Conduction System of the Heart: Setting the Basic Rhythm a. Intrinsic Conduction System b. Homeostatic Imbalances i. Heart Block ii. Ischemia iii. Fibrillation 2. Cardiac Cycle and Heart Sounds a. Mid-to-Late Diastole b. Ventricular Systole c. Early Diastole d. Homeostatic Imbalances i. Murmurs 3. Cardiac Output (CO) a. Regulation of Stroke Volume (SV) b. Factors Modifying Basic Heart Rate (HR) c. Neural (ANS) Controls d. Physical Factors e. Homeostatic Imbalanaces i. Congestive Heart Failure (CHF) ii. Pulmonary Edema II. BLOOD VESSELS (pp. 374–395) A. Microscopic Anatomy of Blood Vessels (pp. 374–377) 1. Tunics 2. Structural Differences between Arteries, Veins, and Capillaries 3. Homeostatic Imbalanaces a. Varicose Veins b. Thrombophlebitis c. Pulmonary Embolism B. Gross Anatomy of Blood Vessels (pp. 378–386) 1. Major Arteries of the Systemic Circulation (Figure 11.12) a. Arterial Branches of the Ascending Aorta i. Right and Left Coronary Arteries b. Arterial Branches of the Aortic Arch i. Brachiocephalic Trunk ii. Left Common Carotid Artery iii. Left Subclavian Artery c. Arterial Branches of the Thoracic Aorta i. Intercostal Arteries ii. Bronchial Arteries iii. Esophageal Arteries iv. Phrenic Arteries d. Arterial Branches of the Abdominal Aorta i. Celiac Trunk ii. Superior Mesenteric Artery iii. Renal Arteries iv. Gonadal Arteries v. Lumbar Arteries vi. Inferior Mesenteric Artery vii. Common Iliac Arteries 2. Major Veins of the Systemic Circulation (Figure 11.13) a. Veins Draining into the Superior Vena Cava i. Radial and Ulnar Veins ii. Cephalic Vein iii. Basilic Vein iv. Subclavian Vein v. Vertebral Vein vi. Internal Jugular Vein vii. Brachiocephalic Vein viii. Azygos Vein b. Veins Draining into the Inferior Vena Cava i. Anterior and Posterior Tibial Veins and Fibular Vein ii. Great Saphenous Veins iii. Common Iliac Veins iv. Gonadal Veins v. Renal Veins vi. Hepatic Portal Vein vii. Hepatic veins 3. Special Circulations (Figures 11.14–11.17) a. Arterial Supply of the Brain and the Circle of Willis b. Fetal Circulation c. Hepatic Portal Circulation C. Physiology of Circulation (pp. 387–395) 1. Arterial Pulse 2. Blood Pressure a. Blood Pressure Gradient b. Measuring Blood Pressure c. Effects of Various Factors on Blood Pressure i. Neural Factors: The Autonomic Nervous System ii. Renal Factors: The Kidneys iii. Temperature iv. Chemicals v. Diet d. Variations in Blood Pressure 3. Capillary Exchange of Gases and Nutrients 4. Fluid Movements at Capillary Beds III. DEVELOPMENTAL ASPECTS OF THE CARDIOVASCULAR SYSTEM (pp. 395, 397) A. Embryonic Development B. Congenital Heart Defects C. Exercise D. Coronary Artery Disease
KEY TERMS aorta aortic arch aortic semilunar valve arteries arterioles ascending aorta atria atrioventricular (AV) node bicuspid (mitral) valve blood pressure brachial vein bradycardia bundle branches cardiac output (CO) cardiac veins cardiovascular system chordae tendineae common carotid artery common hepatic artery coronary arteries coronary artery disease coronary sinus diastolic pressure ductus arteriosus ductus venosus endocardium epicardium femoral artery femoral vein pericardium gastric vein great saphenous vein heart rate (HR) heart sounds hepatic portal vein hepatic veins high blood pressure hypertension hypotension inferior vena cava internal carotid arteries internal jugular vein interstitial fluid (tissue fluid) marginal arteries median cubital vein mediastinum myocardium pacemaker pressure points pulmonary arteries pulmonary circulation pulmonary semilunar valve pulmonary veins pulse Purkinje fibers radial artery radial vein renal arteries renal veins right and left coronary arteries semilunar valves sinoatrial (SA) node subclavian artery subclavian vein superior vena cava systemic circulation systole systolic pressure tachycardia thoracic aorta tricuspid valve valves vascular system vasoconstriction veins ventricles vital signs
LECTURE HINTS 1. Descriptively present the cardiovascular system as the great transportation system of the body, similar to a mail delivery system, that not only carries the oxygen and carbon dioxide people usually relate to it, but also delivers nutrients, removes toxic wastes, conveys heat, and transports the myriad of hormones that are essential to all regulatory functions. Key point: Drawing an analogy between the cardiovascular system and a mail delivery system helps students conceptualize the work of this intricate system. 2. Although the left side of the heart generates more pressure than the right side, approximately the same volume of blood is ejected from each side per beat. Ask students to think about what would happen if this were not the case. Follow up with a discussion on congestive heart failure. Key point: In CHF, blood pumped to the lungs by the right ventricle does not keep pace with blood pumped around the system by the left ventricle. Fluid builds up in the lungs, leading to the predominant symptom of CHF, which is breathing difficulty. 3. Students may recall that the average blood volume of a healthy adult male is 5–6 liters. All blood generally circulates completely through the body in about one minute while at rest. Key point: 5–6 liters/minute is the average resting cardiac output for an average healthy adult male. 4. Compare the body’s self-regulating pacemaker, the SA node, to an artificial pacemaker in function and performance. Describe the 1,000,000 or more times each week that the heart’s pacemaker fires and causes it to pump blood around the system and back again to the heart. Key point: Students are usually quite surprised to learn that humans have a built-in pacemaker that is actually much more efficient, longer lasting, and more versatile than an artificial one. 5.
Stress that the only function of the valves of the heart is to ensure the one-way flow of blood. Explore with the students the consequences of incompetent or stenotic valves. Key point: This provides an opportunity to differentiate between the various types of murmurs and their etiology. 6. Discuss the chordae tendineae, or “heart strings.” Explain their function as similar to the stays of an umbrella, designed to keep the heart valves from turning inside out under extreme pressure. Key point: The reference to something “tugging at their heart strings” gives students a concrete example of the way in which anatomy, particularly of the heart, has an established place in our language and literature. 7. Outline the remarkable engineering involved in the design of the blood vessels, which allows them to absorb the pressure emitted from the heart with each beat and to return blood back to the heart, usually on an uphill course against the constant pull of gravity. Key point: In differentiating between arteries, veins, and capillaries, emphasize that the structure of each type of vessel is related to the differing amounts of pressure they must each absorb from the heart, as well as their respective roles in blood …show more content…
transport. 8. A basic misconception students have is that arteries carry oxygenated blood and veins carry deoxygenated blood. While this is usually true, the heart is a notable exception. Remind students that arteries are defined as vessels that carry blood away from the heart and veins carry blood toward the heart. Key point: The pulmonary arteries carry deoxygenated blood from the right side of the heart to the lungs, and the pulmonary veins return oxygenated blood to the left side of the heart. 9. Veins are more superficial and are occluded when a phlebotomist applies a tourniquet that enables veins to rise as blood is still being pumped distally through arteries running underneath the tourniquet. Key point: Veins are low pressure vessels and need less strength, support, and elasticity than the arteries. 10. In discussing fetal circulation, point out that all fetuses have a “hole in their heart,” and in fact two holes, which allow circulation to be routed around the non-inflated lungs. Explain the fact that if these “holes” don’t close at or shortly after birth, then surgical closure is required, usually to correct a PDA (patent ductus arteriosus). Key point: Again, this is an example of a linguistic reference that has an actual anatomic basis, which students find fascinating. 11. Discuss the blood supply to the heart itself, pointing out that despite the fact that blood fills all the chambers of the heart, the heart cannot nourish itself from the inside. Explain coronary artery disease (CAD) and its common sequelae, the coronary artery bypass graft (known as CABG and pronounced “cabbage”). Key point: It is important for students to recognize that the heart must be infiltrated with its own vascular supply in order to receive the oxygen and nutrients necessary for its survival. Any blockage in the vascular flow will lead to tissue damage, resulting in a myocardial infarction or “heart attack.” Note the difference between open heart surgery (valve replacement, etc.) and open chest surgery (CABG). 12. Differentiate between atherosclerosis and arteriosclerosis, pointing out that “athero” means yellow, fatty plaque, and discuss the role of cholesterol in its development. Point out that there is no such thing as “good” and “bad” cholesterol, and that we actually need both types within our bodies for transportation purposes. Explain that it is simply a matter of ratio, or the proportion of low-density lipids to high. Key point: This is a good time to dispel the notion of good and bad cholesterol, and instead to help students understand that moderation is key to a healthy cardiovascular system. Point out that the lymphatic system dumps fats into the vena cavae immediately before blood returns to the heart. 13. Describe the various methods that can be used to treat atherosclerosis (e.g., stents, angioplasty). Key point: Students are generally familiar with the concept of blocked blood vessels, but are often unaware of treatments other than bypass surgery. 14. Discuss Olestra, the fat substitute, and its physiological effects on the body, including the blood vessels. Key point: Through advertising, students are usually quite familiar with nutritional substitutes, such as fat and sugar substitutes, but they often don’t understand the mechanisms at play and the potential side effects from the use of these substitutes. 15. Discuss smoking and its cardiovascular implications, including arteriovascular insufficiency, ischemia, intermittent claudication with concomitant leg pain and cramps, thrombus formation, and impotence. Key point: The impact of smoking on the cardiovascular system is so significant that it is important to incorporate a discussion of the smoking-related disorders into the class presentation. 16. Present information on deep vein thrombi (DVTs) and their incidence related to bed rest and/or a sedentary lifestyle. Explain their connection to long distance travel, birth control pills, and genetics. Point out the irony that the treatment for DVTs includes bed rest along with anticoagulant medication. Key point: This discussion helps students gain perspective on potential serious homeostatic imbalances of the venous system and their causes. 17. Discuss the correlation of Group A streptococcal infections such as “strep throat” to rheumatic fever and rheumatic heart disease, which can lead to mitral valve damage. Key point: Students are usually familiar with the illness described as “strep throat,” but often are unaware of its serious ramifications. 18. Explain the etiology and pathology associated with hypertension, along with methods of prevention and treatment options. Key point: Since hypertension is one of the major risk factors in coronary artery disease, stroke, congestive heart failure, and kidney failure, presentation of the causative factors and current thinking on prevention and treatment are important concepts for students to understand. Excessive salt in the diet retains more fluid within the vessels and thus increases blood pressure internally, as compared to external stressors that increase blood pressure externally. 19. Explain that the intrinsic electrical conduction can be picked by ECG electrodes placed anywhere on the external skin surface. Key point: Electrical activity goes from the body to the machine and heart paddles placed on an emergency patient are designed to stop the heart and hopefully enable normal autorhythmicity to take over. Explain that a rescuer would not want to give a patient just pulled out of a swimming pool several hundred joules of energy if the deck is not dry. 20. Differentiate between myocardial infarction, stroke, pulmonary embolism, and thrombi. Key point: Students often do not realize that these terms can all be related to one another since they refer to blockage of blood vessels in different parts of the body. 21. Explain the difference between an aneurysm and a ruptured aneurysm. Key point: The media often does not distinguish between these two terms, so students can get confused as to their effects and treatment. 22. Describe all of the different physical, chemical, and neurological factors that can modify heart rate. Key point: Explain to students that a wide variety of factors located all over the body can play a role in determining heart rate.
CLASSROOM DEMONSTRATIONS AND STUDENT ACTIVITIES
Classroom Demonstrations: 1. Film(s) or other media of choice. 2. Show a video of a beating heart, ideally with heart sounds. Stress that while the right side of the heart is a pulmonary pump and the left side a systemic pump, both atria contract at the same time and both ventricles contract at the same time. 3. Use a dissectible heart model to show heart structure. 4. Use a dissectible human torso model to point out the major arteries and veins of the body. 5. Show the chordae tendineae, the “heart strings,” on a dissected heart. 6. Show a chart of various types and grades of heart murmurs, explaining that some of them are considered nonpathological and are merely “functional” (related to low fluid volume, etc.). 7. Play a recording of normal and abnormal heart sounds to accompany your presentation of valve function and malfunction. (Interpreting Heart Sounds is available for loan from local chapters of the American Heart Association.) 8. Demonstrate the recording of an
ECG. 9. Bring in a test tube or show pictures of blood in a test tube containing high fat content. Point out that at times the fat content is so high, you can actually see floating clumps of fat in the specimen. 10. Have a guest speaker from the American Heart Association talk to the class about the risk factors and leading causes of heart disease. 11. Bring in an old mechanical pacemaker and show its placement on the chest wall under the skin. Compare the heart’s own pacemaker, the SA node, to the implanted mechanical device, explaining that artificial pacemakers keep a set pulse rate and are not regulated by increased or decreased activity. 12. Demonstrate the use of defibrillators, including AEDs, and explain their function in cardiac rescue. Also discuss CPR as it relates to heart function. 13. Show pictures of and describe “pitting” edema. Explain how fluid can fill the interstitial spaces to such a degree that an indentation will stay when the skin is pressed with the index finger. 14. Obtain synthetic bypass graft material and compare it in use and effectiveness to the preferred saphenous vein. 15. Describe the different symptoms of impending myocardial infarction (heart attack) in men and women. Provide statistics showing the increase in diagnosis of MI in women. 16. Show a video of a heart operation and the importance of a perfusionist, who assists the heart surgeon. 17. Have a phlebotomist speak to the class about locations to draw blood in children and in adults. Have the speaker explain the difficulties in drawing blood when the patient is obese or dehydrated, and the methods they use during those situations.
Student Activities: 1. Demonstrate how apical and radial pulses are taken, and have students practice on each other. 2. Demonstrate the location of the radial, brachial, carotid, femoral, popliteal, and pedal pulses. Have students locate several of their own and compare their rate and rhythm. Discuss the clinical implications of weak or absent pulses in the extremities. 3. Demonstrate the auscultatory method of taking blood pressure and provide sphygmomanometers and stethoscopes for students to practice on each other. 4. Ask students to bring in a daily record of their blood pressure in the upright and supine positions for a specified period of time to chart and compare. 5. Provide simple drawings of a dissected heart and have the students follow the path of blood as it flows through the various chambers. Ask them to use red and blue pencils to differentiate between oxygenated and deoxygenated blood. Also ask them to label the chambers, valves, septa, and other distinguishing features. 6. Have students run in place or do jumping jacks for 3 minutes, then have them record their radial pulse (pointing out that a radial pulse is always thumb side). Have them continue to take their pulse every 30 seconds for 5 minutes, then graph the results. Point out that a steep decline in the first minute or so indicates rapid recovery by the heart. 7. Provide the students with a diagram of the major blood vessels for labeling. 8. Have students record their salt intake for one week. Provide them with a chart showing salt content in foods and also review the use of food labels. Have them graph their daily salt intake and compare it to the FDA limit. Discuss which foods, like milk products and pickles, are surprisingly high in salt content. 9. Encourage students to obtain CPR training and offer extra credit for documentation of certification during the semester. 10. Have students plan an investigation to learn more about heart rate and heart sounds. Have them select a problem, such as the relationship of age or weight, and determine its effect on heart rate and heart sounds. Have them formulate a testable hypothesis and list the steps for the investigation, including the selection of appropriate equipment and technology. They should implement the investigation, record the data in a chart, and draw conclusions from that data. 11. Have students plan an investigation to determine the effect of time of day on a selected vital sign. They should formulate a testable hypothesis and list the steps in the investigation to test this hypothesis, including the equipment and technology that would be used. With your approval, students should then implement their plan using their classmates as subjects. They should record the data and draw conclusions about the effect of time of day on the selected vital sign. 12. Have your students answer the following question to demonstrate their understanding of how to select appropriate equipment and technology: Mr. Wright is working in his garden. Suddenly he experiences tightness across his chest and knows this is not a good sign. He uses his cell phone to call 911, and rests until the ambulance arrives. The EMT will assess his condition and put electrodes across his chest to measure his heart action. What is the name of this medical equipment? A. Electrocardiograph* B. IV C. Thermometer D. Ophthalmoscope 13. Have a student perform an incremental stationary bicycle test and record heart rate and blood pressure from rest to exhaustion. Note how systolic blood pressure increases at higher exercise workloads and diastolic blood pressure remains nearly the same (important because diastole is when the heart is able to feed itself). 14. Where possible, bring students to a teaching hospital to observe open heart surgery and/or heart transplantation. 15. Have students dissect a cow’s heart both sagittally and transversely to observe the differences in valves, chambers, wall thickness, and right/left sides.
ANSWERS TO END OF CHAPTER REVIEW QUESTIONS
Questions appear on pp. 399–401
Multiple Choice 1. d (Figure 11.3) 2. b (p. 372) 3. d (p. 368; Figure 11.6) 4. a, c (pp. 369–371) 5. c (p. 370) 6. a, c (p. 371) 7. b (p. 362) 8. a, c (p. 374; Figure 11.9) 9. d (p. 378; Figure 11.12) 10. a (Figure 11.12) 11. b (p. 383) 12. a, c, d (pp. 378, 380) 13. b (pp. 392–393) 14. a, b, c (p. 397) 15. c (pp. 372–373) 16. b (p. 362) 17. d (pp. 365–366; Figure 11.2d) 18. b (p. 366; Figure 11.2d) 19. b (pp. 363–364; Figure 11.2b)
SHORT ANSWER ESSAY 20. See Figure 11.2. (pp. 363–364) 21. Right atrium to right ventricle to pulmonary trunk to right and left pulmonary arteries to pulmonary capillaries of the lungs to right and left pulmonary veins to left atrium of the heart. Pulmonary circuit or pulmonary circulation. (p. 365; Figure 11.3) 22. The pericardial (serous) fluid acts as a lubricant to decrease friction as the heart beats. (p. 363) 23. Systole: Period of contraction of the heart (usually refers to ventricular contraction). Diastole: Period of relaxation of the heart musculature. Stroke volume: The amount of blood pumped out by a ventricle with each contraction. Cardiac cycle: The time for one complete heartbeat, from the beginning of one systole to the beginning of the next. (pp. 369, 372) 24. The heart has an intrinsic ability to beat (contract), which is different from all other muscles in the body. Whereas the nervous system may increase or decrease its rate, the heart continues to beat even if all nervous connections are cut. (p. 368) 25. SA node (pacemaker), AV node, AV bundle (bundle of His), bundle branches, Purkinje fibers. (p. 368) 26. Activity of the sympathetic nervous system (as during physical or emotional stress), excess or lack of certain vital ions, increased temperature, hormones (epinephrine, thyroxine), sudden drop in blood volume, age, gender, and exercise. (p. 368) 27. Tunica intima: A single layer of squamous epithelium; provides a smooth, friction-reducing lining for the vessel. Tunica media: A middle layer, consisting of smooth muscle and connective tissue (primarily elastic fibers). The elastic fibers provide for stretching and then passive recoil of vessels close to the heart, which are subjected to pressure fluctuations; the smooth muscle is activated by the sympathetic nervous system when vasoconstriction (and increases in blood pressure) is desired. Tunica externa: The outermost layer, made of fibrous connective tissue; basically a protective and supporting layer. (pp. 374–376) 28. Capillary walls are essentially just the tunica intima (endothelium plus the basement membrane); thus, they are exceedingly thin. (p. 376) 29. Arteries are much closer to the pumping action of the heart and must be able to withstand the pressure fluctuations at such locations. Veins, on the distal side of the capillary beds of the tissues, are essentially low-pressure vessels that need less strength/support/ elasticity than do arteries. (p. 376) 30. The presence of valves, the milking action of skeletal muscles against the veins as the muscles contract, the respiratory pump (pressure changes in the thorax during breathing). (p. 376) 31. Pulmonary arteries carry oxygen-poor blood and pulmonary veins carry oxygen-rich blood. Umbilical arteries carry oxygen-poor blood from the fetus and the umbilical vein carries the most oxygen-rich blood to the fetus. (pp. 365, 383–384) 32. Right wrist: Left ventricle to ascending aorta to aortic arch to brachiocephalic artery to subclavian artery to axillary artery to brachial artery to radial (or ulnar) artery to capillary network of wrist to radial (or ulnar) vein to brachial vein to axillary vein to subclavian vein to right brachiocephalic vein to superior vena cava to right atrium of the heart. Right foot: Left ventricle to ascending aorta to aortic arch to descending aorta to right common iliac artery to external iliac artery to femoral artery to popliteal artery to anterior tibial artery to dorsalis pedis artery to capillary network to anterior tibial vein to popliteal vein to femoral vein to external iliac vein to common iliac vein to inferior vena cava to right atrium of the heart. (Alternatively, the sequence between the capillary network and external iliac vein could be stated as: dorsal venous arch to great saphenous vein.) (Figures 11.12–11.13) 33. The hepatic portal circulation carries nutrient-rich blood from the digestive viscera to the liver for processing before the blood enters the systemic circulation. A portal circulation involves a capillary bed that is both fed and drained by veins; the usual circulation has a capillary bed that is fed by arteries and drained by veins. (pp. 385–386) 34. In a fetus, both liver and lungs are nonfunctional (the liver relatively so). The ductus venosus bypasses the liver. The ductus arteriosus and the foramen ovale bypass the lungs. The umbilical vein carries nutrient-rich and oxygen-rich blood to the fetus through the umbilical cord. (pp. 383–385) 35. Pulse: The alternate expansion and recoil of an artery that occur with each heartbeat. (p. 387) 36. Front of the ear: Temporal artery. Back of knee: Popliteal artery. (p. 387; Figure 11.18) 37. Systolic pressure: Pressure exerted by blood on the arterial walls during ventricular contraction. Diastolic pressure: Pressure exerted by blood on the arterial walls when the ventricles are relaxing (that is, during diastole). (p. 388) 38. Cardiac output is increased by increased venous return and increased heart rate. Peripheral resistance is increased by decreased diameter of the blood vessels and increased blood viscosity. (Figure 11.21) 39. Blood pressure is normally highest in the recumbent position and lowest immediately after standing up; however, the sympathetic nervous system quickly compensates in a healthy individual. Very often an individual can become hypotensive after remaining still in the sitting position for an extended period. (pp. 389–390) 40. Intercellular clefts allow limited passage of solutes and fluid. Fenestrated capillaries allow very free passage of small solutes and fluids. Capillaries lacking these modifications are relatively impermeable. (p. 394) 41. Veins that have become twisted and dilated because of incompetent valves. Inactivity (lack of skeletal milking activity against the veins), which allows the blood to pool in the lower extremities; increased pressure that restricts venous return (as in pregnancy and obesity). (p. 377, 397) 42. Blood flow in arteries is pulsatile because it is under a greater amount of pressure compared to veins. Arteries are located closer to the ventricles, so their walls must be capable of expanding and contracting under the changes in pressure when the ventricles contract. When blood reaches the veins, the pressure is very low, and so instead of veins having a pulsatile ability to maintain pressure, they instead have valves to prevent backflow. (pp. 387–388) 43. The greater the cross-sectional area in a blood vessel, the faster that blood can flow through that vessel. Smaller vessels, like capillaries, are only one cell thick in diameter, which slows down blood flow and allows nutrient and gas exchange to occur. (p. 374) 44. Arterioles are the blood vessels that are most important in regulating vascular resistance. These vessels can constrict as a result of activity from the sympathetic nervous system, which alters blood pressure. Atherosclerosis in these vessels also causes narrowing due to plaque deposits, which also affects blood pressure. (p. 388)
ANSWERS TO CRITICAL THINKING AND CLINICAL APPLICATION QUESTIONS 45. Hypertension: abnormally elevated or high blood pressure (generally described as systolic pressure consistently over 140 mm Hg and diastolic pressure consistently over 90 mm Hg in younger adults). (pp. 391, 394) Arteriosclerosis: “hardening of the arteries,” the result of deposit of fatty-cholesterol substances and calcium salts onto the inner walls of the blood vessels. Arteriosclerosis can be a direct cause of hypertension because it decreases the elasticity of the arteries (thereby increasing peripheral resistance). (p. 393) Hypertension is often called the “silent killer” because it progresses initially (and often over a prolonged period) without obvious symptoms. Three lifestyle habits that might help prevent cardiovascular disease are regular exercise, a diet low in saturated fats and salt, and a decrease in stress. (Quitting smoking would also help.) 46. She has pulmonary edema. The right side of the heart is still sending blood to the lungs, but the left side of the heart, the systemic pump, is not pumping blood entering its chamber (from the pulmonary circuit) to the systemic circulation. As the pressure increases in the pulmonary vessels, they become leaky, and fluid enters the tissue spaces of the lungs. (p. 374) 47. Incompetence (not stenosis) of the pulmonary semilunar valve. Incompetent valves produce swishing sounds, and the pulmonary semilunar valve is heard at the superior left corner of the heart, as indicated in this question. (pp. 371–372) 48. The compensatory mechanisms of Mrs. Johnson include an increase in heart rate and an intense vasoconstriction, which allows blood in various blood reservoirs to be rapidly added to the major circulatory channels. (pp. 388–391; Figure 11.21) 49. The left atrium and the posterior portion of the left ventricle. (p. 367; Figure 11.2) 50. Chronically elevated due to increased blood volume. ADH promotes retention of water by the kidneys. (pp. 390–391; Figure 11.21) 51. Blood flow is increased to areas of need and decreased to areas of non-need due to constriction and dilation of arterioles as blood will flow down pathway of least resistance. Competition for blood flow between the GI tract, which needs more blood circulation for absorption, and the skeletal muscles, which simultaneously need more blood for exercise, will cause indigestion much more quickly than muscle cramping. (pp. 385, 389–390) 52. Standing erect for prolonged periods enables gravity to pool blood in lower extremities, particularly in the absence of muscle pump activity which increases venous return during movement. Reduction in venous return causes reductions in stroke volume, causing lightheadedness as blood flow to brain is reduced. Standing in a hot environment will also produce sweating, vasodilation, and a reduction of blood plasma, which further decreases stroke volume. (p. 376)
CLASSROOM DEMONSTRATIONS AND STUDENT ACTIVITIES
Classroom Demonstrations: 1. Film(s) or other media of choice. 2. Show a video of a beating heart, ideally with heart sounds. Stress that while the right side of the heart is a pulmonary pump and the left side a systemic pump, both atria contract at the same time and both ventricles contract at the same time. 3. Use a dissectible heart model to show heart structure. 4. Use a dissectible human torso model to point out the major arteries and veins of the body. 5. Show the chordae tendineae, the “heart strings,” on a dissected heart. 6. Show a chart of various types and grades of heart murmurs, explaining that some of them are considered nonpathological and are merely “functional” (related to low fluid volume, etc.). 7. Play a recording of normal and abnormal heart sounds to accompany your presentation of valve function and malfunction. (Interpreting Heart Sounds is available for loan from local chapters of the American Heart Association.) 8. Demonstrate the recording of an ECG. 9. Bring in a test tube or show pictures of blood in a test tube containing high fat content. Point out that at times the fat content is so high, you can actually see floating clumps of fat in the specimen. 10. Have a guest speaker from the American Heart Association talk to the class about the risk factors and leading causes of heart disease. 11. Bring in an old mechanical pacemaker and show its placement on the chest wall under the skin. Compare the heart’s own pacemaker, the SA node, to the implanted mechanical device, explaining that artificial pacemakers keep a set pulse rate and are not regulated by increased or decreased activity. 12. Demonstrate the use of defibrillators, including AEDs, and explain their function in cardiac rescue. Also discuss CPR as it relates to heart function. 13. Show pictures of and describe “pitting” edema. Explain how fluid can fill the interstitial spaces to such a degree that an indentation will stay when the skin is pressed with the index finger. 14. Obtain synthetic bypass graft material and compare it in use and effectiveness to the preferred saphenous vein. 15. Describe the different symptoms of impending myocardial infarction (heart attack) in men and women. Provide statistics showing the increase in diagnosis of MI in women. 16. Show a video of a heart operation and the importance of a perfusionist, who assists the heart surgeon. 17. Have a phlebotomist speak to the class about locations to draw blood in children and in adults. Have the speaker explain the difficulties in drawing blood when the patient is obese or dehydrated, and the methods they use during those situations.
Student Activities: 1. Demonstrate how apical and radial pulses are taken, and have students practice on each other. 2. Demonstrate the location of the radial, brachial, carotid, femoral, popliteal, and pedal pulses. Have students locate several of their own and compare their rate and rhythm. Discuss the clinical implications of weak or absent pulses in the extremities. 3. Demonstrate the auscultatory method of taking blood pressure and provide sphygmomanometers and stethoscopes for students to practice on each other. 4. Ask students to bring in a daily record of their blood pressure in the upright and supine positions for a specified period of time to chart and compare. 5. Provide simple drawings of a dissected heart and have the students follow the path of blood as it flows through the various chambers. Ask them to use red and blue pencils to differentiate between oxygenated and deoxygenated blood. Also ask them to label the chambers, valves, septa, and other distinguishing features. 6. Have students run in place or do jumping jacks for 3 minutes, then have them record their radial pulse (pointing out that a radial pulse is always thumb side). Have them continue to take their pulse every 30 seconds for 5 minutes, then graph the results. Point out that a steep decline in the first minute or so indicates rapid recovery by the heart. 7. Provide the students with a diagram of the major blood vessels for labeling. 8. Have students record their salt intake for one week. Provide them with a chart showing salt content in foods and also review the use of food labels. Have them graph their daily salt intake and compare it to the FDA limit. Discuss which foods, like milk products and pickles, are surprisingly high in salt content. 9. Encourage students to obtain CPR training and offer extra credit for documentation of certification during the semester. 10. Have students plan an investigation to learn more about heart rate and heart sounds. Have them select a problem, such as the relationship of age or weight, and determine its effect on heart rate and heart sounds. Have them formulate a testable hypothesis and list the steps for the investigation, including the selection of appropriate equipment and technology. They should implement the investigation, record the data in a chart, and draw conclusions from that data. 11. Have students plan an investigation to determine the effect of time of day on a selected vital sign. They should formulate a testable hypothesis and list the steps in the investigation to test this hypothesis, including the equipment and technology that would be used. With your approval, students should then implement their plan using their classmates as subjects. They should record the data and draw conclusions about the effect of time of day on the selected vital sign. 12. Have your students answer the following question to demonstrate their understanding of how to select appropriate equipment and technology: Mr. Wright is working in his garden. Suddenly he experiences tightness across his chest and knows this is not a good sign. He uses his cell phone to call 911, and rests until the ambulance arrives. The EMT will assess his condition and put electrodes across his chest to measure his heart action. What is the name of this medical equipment? A. Electrocardiograph* B. IV C. Thermometer D. Ophthalmoscope 13. Have a student perform an incremental stationary bicycle test and record heart rate and blood pressure from rest to exhaustion. Note how systolic blood pressure increases at higher exercise workloads and diastolic blood pressure remains nearly the same (important because diastole is when the heart is able to feed itself). 14. Where possible, bring students to a teaching hospital to observe open heart surgery and/or heart transplantation. 15. Have students dissect a cow’s heart both sagittally and transversely to observe the differences in valves, chambers, wall thickness, and right/left sides.