pulmonary capillary
        mitral valve
        aortic semilunar valve
        tricuspid valve
        pulmonary vein
 12   aorta
        left ventricle
        right ventricle
        right atrium
        pulmonary semilunar valve
        left atrium
        pulmonary artery
1.                                                                        
2.                                                                        
3.                                                                        
4.                                                                        
5.                                                                        
6.                                                                        
7.                                                                        
8.                                                                        
9.                                                                        
10.                                                                        
11.                                                                        
12.   aorta                                 

D. Label the Figure — The Heart

Study figure 13.1 and label all structures of the heart, including the four valves. When finished, check your work with figure 13.11 in your text.

Figure 13.1

IV. Cardiac Cycle and Heart Sounds

The two atria fill with blood and then contract simultaneously. This is followed by simultaneous contraction of both ventricles, which sends blood through the pulmonary and systemic circulations. Contraction of the ventricles closes the AV valves and opens the semilunar valves; relaxation of the ventricles causes the semilunar valves to close. The closing of first the AV valves and then the semilunar valves produces the “lub-dub” sounds heard with a stethoscope.

A. Multiple Choice

1. The terms systole and diastole refer, respectively, to the

a.  contraction phase and relaxation phase of the atria.
b.  relaxation phase and contraction phase of the atria.
c.  contraction phase and relaxation phase of the ventricles.
d.  relaxation phase and contraction phase of the ventricles.
e.  the simultaneous contraction and relaxation phases of both the atria and the ventricles.

1. During normal ventricular contraction, what fraction of the end-diastolic volume is ejected as the stroke volume?

a.  one-fourth
b.  one-third
c.  one-half
d.  two-thirds
e.  three-fourths

1. At rest, each cardiac cycle lasts about 0.8 seconds; of which systole lasts ___ seconds, and diastole lasts ____ seconds.

a.  0.3; 0.5
b.  0.4; 0.4
c.  0.1; 0.7
d.  0.6; 0.2
e.  0.2; 0.6

1. During one cardiac cycle, the major difference between the left and the right halves of the heart is that the

a.  left heart pumps a greater volume of blood than the right heart.
b.  right heart contracts shortly before the left heart.
c.  right heart pumps blood with less force (at lower pressure) than the left heart.
d.  left heart has a shorter cardiac cycle duration than the right heart.

1. The first heart sound results from vibrations generated by the

a.  opening of the AV valves.
b.  closing of the AV valves.
c.  opening of the semilunar valves.
d.  closing of the semilunar valves.
e.  Both b and d are correct.

B. True or False/Edit

1. Normally, both atria contract at the same time, followed shortly by both ventricles contracting at the same time.
2. Venous blood returning to fill the heart (venous return) is greatest during systole.
3. The contraction of both atria is essential for life because it delivers about 80% of the total volume of blood to the ventricles for subsequent ejection.
4. During both isovolumetric contraction and isovolumetric relaxation phases, all four valves in the heart (2 AV and 2 semilunar) are closed.
5. During inhalation particularly, the first heart sound may be “split” into two separate sounds as the tricuspid and mitral heart valves close individually.
6. A streptococcus bacterial throat infection in susceptible persons may lead to rheumatic fever and rheumatic endocarditis, resulting in damage to the heart valves and detectable murmurs.

1.  
2. Simple septal defects are usually congenital (from birth), resulting in the flow of blood from the right side of the heart to the left side of the heart since the pressure is higher on the right side.

V. Electrical Activity of the Heart and Electrocardiogram

The pacemaker region of the heart (SA node) exhibits a spontaneous depolarization that causes action potentials, resulting in the automatic beating of the heart. Electrical impulses are conducted by myocardial cells in the atria and are transmitted to the ventricles by specialized conducting tissue. Electrocardiogram waves correspond to the electrical events in the heart as follows: P wave (depolarization of the atria); QRS wave (depolarization of the ventricles); and T wave (repolarization of the ventricles).

A. Multiple Choice

1. The sinoatrial (SA) node region of the right atrium is the normal pacemaker of the heart because this region

a.  demonstrates spontaneous electrical activity.
b.  depolarizes to threshold before other cardiac regions.
c.  has Ca2+ diffusing through Ca2+ channels into the cardiac fibers.
d.  develops pacemaker potentials during diastole.
e.  All of these statements are correct.

1. Action potentials in myocardial cells (not SA node fibers) have a characteristic plateau phase, which is caused primarily by the

a.  slow outward diffusion of Na+.
b.  fast inward diffusion of Na+.
c.  fast outward diffusion of Ca2+.
d.  slow inward diffusion of Ca2+.

1. Which statement about the normal electrocardiogram (ECG) tracing is false?

a.  Lead I is a recording from the right arm to the left arm.
b.  The unipolar leads are found only on the chest.
c.  There are a total of twelve standard ECG leads that “view” the changing pattern of the heart’s electrical activity.
d.  There are six unipolar chest leads.
e.  Lead III is a recording from the left arm to the left leg.

1. Which statement about the normal electrocardiogram (ECG) tracing is false?

a.  The T wave represents depolarization of the atria.
b.  The QRS wave represents depolarization of the ventricles.
c.  The repolarization of the atria is hidden by the QRS wave.
d.  The P wave occurs shortly before the QRS wave.
e.  All of these statements about the ECG are true.

1. The second heart sound (S2) is heard while the ECG is recording
2.                     the corresponding

a.  P wave.
b.  P-R interval.
c.  QRS wave.
d.  T wave.
e.  S-T segment.

B. True or False/Edit

1. Since a fibrous skeleton separates the atria from the ventricles of the heart, the electrical excitation and mechanical contraction of the ventricle is separate from that of the atria.
2. In the SA node region of the heart, spontaneous, automatic depolarization of the pacemaker fibers (diastolic depolarization) results from the more rapid entry of K+ ions down their electrochemical gradient.
3. As the pacemaker fibers of the atria depolarize to threshold, the inward current of Ca2+ produces not only the upward phase of the action potential but also the mechanical contraction that follows.

1.  
2. Diastolic depolarization occurs faster in response to epinephrine and norepinephrine (catecholamines) because stimulation of the β1-adrenergic receptors produces cAMP second messengers that keep the HCN channels open.
3. An ectopic pacemaker (or ectopic focus) is a cluster of myocardial cells located away from the SA node that take over and regulate the cardiac pace.
4. The rate of impulse conduction from the SA node is slowed as it passes through the AV node, causing a time delay before the ventricles are excited.
5. The electrical depolarization of myocardial cells during the cardiac cycle stimulates the opening of voltage-gated Ca2+ channels in the sarcolemma that allows calcium ions to diffuse down its concentration gradient and into the cells.
6. The excitation-contraction coupling in myocardial cells depends on the calcium-stimulated-calcium-release mechanism that releases stored Ca2+ from the sarcoplasmic reticulum, which joins the Ca2+ that has already entered from outside the cells in response to depolarization.
7. During the excitation of myocardial cells the rapid entry of Ca2+ into the cytoplasm stimulates contraction by binding directly to myosin filaments.
8. Unlike skeletal muscles, heart muscle cannot maintain a sustained maximal contraction (tetany).
9. The summation of myocardial cell contractions is prevented primarily by their relatively short refractory period.
10. The body is a good conductor of electricity because tissue fluids contain a high concentration of ions that move in response to changes in the membrane potential differences, thereby creating current.
11. The electrocardiogram (ECG) wave patterns that are designated P, QRS, and T represent recordings of single action potentials from specific regions in the heart.

1.  

C. Label the Figure — The Conduction System of the Heart

Study the drawing of the electrical conduction pathway of the heart in figure 13.2. Then write the words that best describe the conduction pathway structures indicated by the blank lines on the figure. Remember this is the pathway for electrical excitation — the mechanical contraction of cardiac muscle fibers will follow shortly. See figure 13.20 in the text to check your work.

Figure 13.2    The conduction system of the heart.

VI. Blood Vessels

The thick muscle layer of arteries allows them to transmit blood ejected from the heart under high pressure, and the elastic recoil of the large arteries further contributes to blood flow. The thinner muscle layer of veins allows them to distend when an increased amount of blood enters them, and their one-way valves ensure that blood flows back to the heart. Capillaries are composed of only one layer of endothelium, which facilitates the rapid exchange of materials between the blood and tissue fluid.

A. Multiple Choice

1. ___   78.    The blood vessel layer composed primarily of smooth muscle is called the tunica _______.

a.  externa
b.  media
c.  interna
d.  endothelium

1. ___   79.    Which of the following statements about arteries and veins is false?

a.  Arteries have more smooth muscle than comparable veins.
b.  Arteries carry blood under higher pressure.
c.  Veins have one‑way valves, promoting flow in only one direction.
d.  Veins collapse thereby providing the greatest resistance to blood flow in the circulatory system.
e.  All of these statements regarding arteries and veins are true.

1. ___   80.    The “business ends” of the circulatory system in which the exchanges of gases and nutrients occur, are important blood vessels known as

a.  arteries.
b.  arterioles.
c.  capillaries.
d.  venules.
e.  veins.

1. ___   81.    In the central nervous system (CNS), the type of capillary that lacks intercellular channels and helps form the blood-brain barrier, is called a

a.  continuous capillary.
b.  discontinuous capillary.
c.  fenestrated capillary.

1. ___   82.    Which of the following mechanisms does not play an important role in the normal return of venous blood to the heart?

a.  the inhalation (inspiratory) phase of normal breathing
b.  large skeletal muscle contractions (pump)
c.  the higher average hydrostatic pressure in the veins than that found in the heart
d.  standing upright, perfectly still

B. True or False/Edit

1. ___   83.    Compared to larger arteries, smaller arteries and arterioles are less elastic and have a thicker layer of smooth muscle for their diameters.
2. ___   84.    In skeletal muscle at rest, the relatively high resistance to blood flow in the small arteries and arterioles reduces capillary blood flow to about 5%-10% of its maximum capacity.
3. ___   85.    Fenestrated capillaries of the kidneys, endocrine glands, and intestines have wide intercellular pores or “windows” which are covered by a mucoprotein layer that restricts the passage of certain molecules (especially proteins) that might otherwise pass through the large capillary pores.
4. ___   86.    Exposed to cytokines such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF), new blood vessels can form from pre-existing blood vessels – a process known as angiogenesis.
5. ___   87.    Varicose veins can result from extra blood accumulating in large veins over a long period of time, thereby stretching these vessels and making venous valves less efficient — no longer able to ensure the one-way flow of blood to the heart.

VII. Atherosclerosis and Cardiac Arrhythmias

Atherosclerosis is a disease process that can lead to obstruction of coronary blood flow. As a result, the electrical properties of the heart and its ability to function as a pump may be seriously compromised. Abnormal cardiac rhythms, or arrhythmias, can be detected by the abnormal electrocardiogram patterns they produce.

A. Multiple Choice

1. ___   88.    Which of the following events is not considered part of the progression that occurs during the development of long-term atherosclerosis?

a.  Monocytes, attracted to the tunica intima region of the damaged endothelium, engulf lipids and take on a “foamy cells” appearance.
b.  Gray-white “fatty streaks” formed by lipid-filled macrophages, protrude into the lumen of arteries and thus reduce blood flow.
c.  White blood cells (phagocytes) attempt to attack and reject the developing atheroma as a foreign substance.
d.  Fibrous plaques may form, composed of accumulated lipids, white blood cells, and debris, covered by a cap of connective tissue and smooth muscle cells.
e.  All of these events are part of the long-term progression in atherosclerosis.

1. ___   89.    Which of the following is not considered a risk factor in the development of atherosclerosis?

a.  advanced age
b.  smoking
c.  high blood HDL — cholesterol
d.  hypertension
e.  high blood LDL — cholesterol

1. ___   90.    Which of the following statements about low-density lipoproteins (LDLs) is false?

a.  In the liver, LDL consists of droplets of cholesterol, neutral fat, free fatty acids, and phospholipids surrounded by an outer layer of protein molecules.
b.  LDL levels are typically higher in females and in exercising males than in those who are inactive.
c.  The apolipoproteins molecules in LDLs are recognized by specific receptors located on various body cells resulting in attachment and ingestion of the LDLs by receptor-mediated endocytosis.
d.  Persons with high blood LDL levels usually have a low number of LDL receptors in their livers.
e.  LDL blood levels rise in persons with high cholesterol, in those eating high-fat diets, and in people with familial hypercholesteremia.

1. ___   91.    Which of the following statements about myocardial infarction (MI) is false?

a.  An MI is commonly referred to by the general public as a “heart attack.”
b.  An MI may be detected by changes in the S‑T segment of the ECG.
c.  Since myocardial cells are adapted to respire anaerobically for several hours, an MI takes time to develop.
d.  An MI can be diagnosed by the abnormal release of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) enzymes released from the infarcted cells.
e.  All of these statements regarding an MI are true.

1. ___  92.     Which of the following arrhythmias is best diagnosed by following changes in the P-R interval of the electrocardiogram (ECG)?

a.  flutter
b.  fibrillation
c.  tachycardia
d.  bradycardia
e.  AV node block

B. True or False/Edit

1. ___   93.    Atherosclerosis, accompanied by heart disease and stroke, is responsible for about 50% of the deaths in the United States, Europe, and Japan.
2. ___   94.    “Fatty streaks” are gray‑white areas that protrude from the tunica intima into the lumen of arteries; and are even present in children to a small degree in the aorta and coronary arteries of children aged 10 to 14.

1.  
2. ___   95.    During the progression of atherosclerosis, lymphocytes may engulf lipids while passing through the endothelium of arteries, developing into “foamy cells.”
3. ___   96.    The measurement of C-reactive protein levels in the blood appears to be a stronger predictor of atherosclerotic heart disease than the blood LDL cholesterol level..
4. ___   97.    People who eat a diet high in cholesterol and saturated fat, and people with familial hypercholesterolemia, have a high blood HDL concentration because their livers have a low number of HDL receptors.
5. ___   98.    Drugs known as statins can lower the blood levels of LDL-cholesterol because they function as inhibitors of the enzyme HMG-Coenzyme A reductase, resulting in a decrease in the synthesis of cholesterol by the liver.
6. ___   99.    The antioxidant property of vitamins C, E, and beta-carotene as well as the drug probucol appear important due to the ability of these substances to inhibit the oxidation of LDL that contributes to the progression of atherosclerosis.
7. ___ 100.    Persons having higher plasma LDL-cholesterol concentrations and lower plasma HDL-cholesterol concentrations appear to have a lower risk of developing atherosclerosis.
8. ___ 101.    About 40%-50% of the calories eaten in a typical fast‑food meal are derived from the ingestion of fat; whereas eating one meal of oily fish such as salmon a week can significantly reduce the risk of myocardial infarction.
9. ___ 102.    Ischemia is an inadequate flow of blood (and an inadequate supply of oxygen)             to any tissue, including the myocardium.
10. ___ 103.    Myocardial infarction (MI) resulting from occlusion of the coronary arteries is the leading cause of death in the western world.
11. ___ 104.    Following coronary bypass surgery and restoration of coronary blood flow, dead myocardial cells (necrosis) can be replaced by mitosis of neighboring healthy cells.
12. ___ 105.    The very serious, even lethal heart rhythm characterized by circus rhythms in which electrical waves are recycled around continuously changing pathways in the heart, best describes third degree, or complete, AV node block.

VIII. Lymphatic System

Lymphatic vessels absorb excess tissue fluid and transport this fluid — now called lymph — to ducts that drain into veins. Lymph nodes, and lymphoid tissue in the thymus, spleen, and tonsils produce lymphocytes, which are white blood cells involved in immunity.

A. Multiple Choice

1. ___ 106.    Which of the following is not a basic function of the lymphatic system?
2. a.  transport interstitial (tissue) fluid back to the blood
3. b.  transport lymph via thoracic ducts to the right and left subclavian veins
4. c.  transport fat absorbed from the small intestine to the blood
5. d.  help in the immunological defense against disease‑causing agents
6. e.  All of these are lymphatic system functions.
7. ___ 107.    Due to the unique structure of lymph capillaries, lymph contains all of the following substances, except
8. a.  interstitial proteins.
9. b.  interstitial microorganisms.
10. c.  interstitial RBCs and WBCs.
11. d.  interstitial fluid.
12. e.  absorbed fat.
13. ___ 108.    Lymph fluid from around the body eventually flows into lymphatics that merge and drain directly into the
14. a.  right and left subclavian veins.
15. b.  superior and inferior vena cavae.
16. c.  aorta.
17. d.  right atrium.
18. e.  right and left pulmonary veins.

1.  
2. ___ 109.    Which of the following is not considered a lymphoid organ since it does not contain phagocytic cells and germinal centers for the production of lymphocytes?
3. a.  the thymus gland
4. b.  the thyroid gland
5. c.  the tonsils
6. d.  the spleen
7. e.  All of these are considered lymphoid organs.

B. True or False/Edit

1. ___ 110.    Like veins, lymphatic vessels have the same three vessel layers and one-way valves to prevent the backward flow of lymph.
2. ___ 111.    Lymph is formed by the filtration of blood plasma from capillaries, forming filtrate that ultimately returns to the blood to complete the cycle.
3. ___ 112.    Lymph nodes germinal centers contain phagocytic cells that help to remove pathogens from lymph.
4. ___ 113.    The lymphatic system may contribute to the spread of cancer (metastasis) since cancer cells can enter and later exit the porous lymphatic capillaries.

Chapter Review

B. Essay

Essay Tutorial

This essay tutorial will answer the first essay question found in the “Review Activities” section of your Human Physiology textbook. Please read Essay Question 1 in the “Test Your Understanding of Concepts and Principles” section located at the end of chapter 13 and let me guide you through one possible answer. Watch for key terms in boldface type, helpful tips and general suggestions on writing the essay or short‑answer questions. Enjoy!
114.  Describe how the pacemaker cells produce a spontaneous diastolic depolarization, and how this leads to the production of action potentials.
Answer. During the resting period (diastole) of the heart, the fibers of the sinoatrial (SA) node region of the right atrium have unique channels that open in response to membrane hyperpolarization (approaching –60 mV) left over from the previous action potential.  Since these channels are permeable to both Na+ and K+, the predominate entry of Na+ results in the net depolarization of these pacemaker cells producing spontaneous diastolic depolarization. Once threshold is reached, voltage-gated Ca2+ channels in the plasma membrane open resulting in the influx of Ca2+ that produces the upward phase of the action potential tracing and also results in contraction of these myocardial cells.  After the spike, voltage-gated K+ channels open and the outward diffusion of K+ produces repolarization of the membranes that once again approach –60 mV with hyperpolarization that follows to repeat the cycle. The term “spontaneous” refers to the inherent property of myocardial pacemaker cells to beat automatically and on their own without the assistance of nerves or hormones. This property is known as automaticity.

OK, now that wasn’t so hard was it? Here are some more.
115.  Draw and label two consecutive heart beats as recorded on the electrocardiogram (ECG). In sequence describe what occurs in the heart to create each electrical event. (Hint: This is a favorite test question!)

116.  In three columns compare and contrast the structure and related functions of (a) arteries, (b) veins, and (c) lymph vessels. (Hint: Use a table format here, OK?)

117.  Describe the first two events that occur when blood begins to clot starting from both the intrinsic pathway and the extrinsic pathway. State the important differences in these two pathways. Then, write the final two enzymatic steps in the formation of a fibrin clot (notice that these last steps are the same for both pathways).

118.  Trace the recycling pathway of plasma fluid from capillary blood, through the extracellular (interstitial) spaces, its conversion to lymph fluid, and transport through lymph vessels to become part of blood once again. Name all structures involved and the forces (or pressures) that keep the fluids moving continuously. (Hint: Work slowly, this is difficult, but the result will give you an excellent overview of the lymphatic system.)

119.  Describe the ABO blood typing system — including the genotypes responsible, the synthesis of A and B antigens from the DNA code, and the differences between the antibodies which are found in the plasma and the A and B antigens which are found on the red blood cell membrane.

Answers — Chapter 13

1. Functions and Components of the Circulatory System
2. 1. a, 2. c, 3. b, 4. c,
3. 5. T, 6. T, 7. F—Replace “excretory” with “circulatory”
4. Composition of the Blood
5. 8. c, 9. b, 10. b, 11. d, 12. c, 13. a, 14. d,
6. 15. e, 16. b, 17. e, 18. e, 19. b, 20. b,
   21. c, 22. a, 23. d,
7. 24. F—Replace “venous” with “arterial” and “blue” with “red,” 25. T, 26. T, 27. F—Only gamma globulins are antibodies; alphas and betas transport lipids 28. T, 29. F—Replace “lymphocyte” with “neutrophil,” 30. F—Replace “monocytes” with “lymphocytes,” 31.F—Leukemia represents abnormal WBCs, 32. T, 33. T, 34. T, 35. T, 36. F—Replace “thromboxane As” with “prostacyclin,” 37. T, 38. F—Switch “plasma” and “serum,” 39. T
8. Structure of the Heart
9. 40. a, 41. c, 42. d
10. 43. T, 44. T, 45. F—Switch “right” and “left,” 46. T
11. 47. 6, 9, 11, 2, 7, 12, 10, 3, 1, 4, 8, 5
12. Label the Figure — The Heart; See figure 13.11 in the text.
13. Cardiac Cycle and Heart Sounds
14. 48. c, 49. d, 50. a 51. c, 52. b
15. 53. T, 54. F—Replace “systole” with “diastole,” 55. F—Atrial contraction is not essential for life, 56. T, 57. T, 58. T, 59. F—Switch “right” and “left;” replace “higher” with “lower”
16. Electrical Activity of the Heart and the Electrocardiogram
17. 60. e, 61. d, 62. b, 63. a, 64. d
18. 65. F-Excitation-contraction starts in the atria; spreads by gap junctions to the ventricles, 66. F—Replace K with Na, 67. T, 68. T, 69. T, 70. T, 71. T, 72. T, 73. F—Replace “myosin” with “troponin,” 74. T
    75. F—Replace “short” with “long,”
    76. T, 77. F—The ECG represents total potential changes of all myocardial cells in the heart
19. Label the Figure—The Conduction System of the Heart; See figure 13.20 in the text.
20. Blood Vessels
21. 78. b, 79. d, 80. c, 81. a, 82. d
22. 83. T, 84. T, 85. T, 86. T, 87. T
23. Atherosclerosis and Cardiac Arrhythmias
24. 88. c, 89. c, 90. b, 91. c, 92. e
25. 93. T, 94. T, 95. F—Replace “lymphocytes” with “monocytes,” 96. T, 97. F—Replace “HDL” with “LDL” (twice), 98. T, 99. T, 100. F—Switch “LDL” and “HDL”
26. 101. T, 102. T, 103. T, 104. F—myocardial necrosis is permanent, 105. F—Replace “third-degree, or complete AV block” with “ventricular fibrillation”
27. Lymphatic System
28. 106. e, 107. c, 108. a, 109. b
29. 110. T, 111. T, 112. F—Germinal centers produce lymphocytes, 113. T