Ch 13 Summary Cardiovascular System PDF

CHAPTER 13 The Cardiovascular System: Cardiac Function 421 CHAPTER REVIEW SUMMARY 13.1 An Overview of the Cardiovascular System, p. 390 • The cardiovascular system includes the heart, blood vessels, and blood. • The heart is a muscular organ possessing four chambers: the left and right atria, w...

CHAPTER 13 The Cardiovascular System: Cardiac Function 421 CHAPTER REVIEW SUMMARY 13.1 An Overview of the Cardiovascular System, p. 390 • The cardiovascular system includes the heart, blood vessels, and blood. • The heart is a muscular organ possessing four chambers: the left and right atria, which receive blood as it returns to the heart from the vasculature, and the left and right ventricles, which pump blood away from the heart through the vasculature. • The blood vessels (arteries, arterioles, capillaries, venules, and veins) function as conduits for blood flow. • Blood consists of a liquid (plasma) in which the other components (erythrocytes, leukocytes, and platelets) are suspended. • Blood acts as a medium that carries oxygen and nutrients to the body’s cells while it carries away carbon dioxide and other waste products. Cardiovascular, Anatomy Review: Blood Vessels Cardio vascular, Anatomy Review: The Heart Cardiovascular, Cardiac Action Potential Cardiovascular, Cardiac Cycle 13.2 The Path of Blood Flow Through the Heart and Vasculature, p. 392 • The vasculature is divided into a pul- atrium, where the blood then enters the right ventricle. • In contrast to the series flow of blood through the right and left sides of the heart, blood flow through the systemic circuit takes the form of parallel flow, with different arteries supplying fresh blood to different organs. • The branching of blood vessels ensures that each capillary bed receives fresh blood. into the cells is important in triggering heart muscle contractions. • The heart’s electrical activity can be recorded using electrodes placed on the skin surface, yielding an electrocardiogram (ECG), which consists of three phases: a P wave, corresponding to atrial depolarization; a QRS complex, corresponding to ventricular depolarization; and a T wave, corresponding to ventricular repolarization. Cardiovascular, Anatomy Review: The Heart Cardiovascular, Cardiac Action Potential Pathway of Blood Through the Heart Action Potentials in Autorhythmic Cells Intrinsic Conduction System of the Heart 13.3 Anatomy of the Heart, p. 395 • The heart is located in the thoracic cavity Generation of the Action Potential and is surrounded by a peri-cardial sac. • The heart wall is made up of the epicardium, the myocardium, and the endothelium; most of the heart consists of the myocardium. • Valves in the heart ensure unidirectional flow of blood. Atrioventricular valves allow blood to flow from atrium to ventricle, whereas semilunar valves allow blood to flow from ventricle to artery (left ventricle to aorta and right ventricle to pulmonary trunk). 13.4 Electrical Activity of the Heart, p. 397 Propagation and Velocity of the Action Potential 13.5 The Cardiac Cycle, p. 407 • The cardiac cycle is divided into two • distinct periods: diastole (ventricular relaxation), during which ventricular filling occurs, and systole (ventricular contraction), during which the exit of blood from the ventricles (ejection) occurs. Aortic pressure varies throughout the cardiac cycle; it rises to a maximum (systolic pressure, SP) during systole and falls to a minimum (diastolic pressure, DP) during diastole. The average pressure throughout the cycle, which represents the driving force for blood flow through the systemic circuit, is the mean arterial pressure (MAP). Ventricular volume falls to a minimum at the end of systole (end-systolic volume, ESV) and rises to a maximum at the end of diastole (end-diastolic volume, EDV). The difference between these volumes is the stroke volume (SV), the volume pumped by each ventricle in a single heartbeat. The pressure-volume curve provides information about how well the heart is functioning. Copyright © 2017. Pearson Education, Limited. All rights reserved. • The heart muscle fibers that make monary circuit, which supplies blood to up the heart’s conduction system are • the lungs, and a systemic circuit, which specialized to initiate action potentials supplies blood to all other organs and and conduct them rapidly through the tissues of the body. myocardium. • In the pulmonary circuit, blood be• Contractions of the heart are trig• comes oxygenated and gives up carbon gered on a regular basis by action dioxide; in the systemic circuit, it bepotentials initiated by pacemaker cells comes deoxygenated and picks up carconcentrated in certain regions of the bon dioxide. myocardium. • Blood is ejected from the right ventricle • Normally the heartbeat is driven by • through the pulmonary semilunar valve pacemakers in the sinoatrial (SA) node, into the pulmonary trunk, which divides located in the upper right atrium. into left and right pulmonary arteries, • Following each action potential, pacecarrying deoxygenated blood to the lungs. maker cells exhibit slow, spontaneous • • The pulmonary veins carry blood away depolarizations (pacemaker potentials) from the lungs and deliver it to the left that eventually depolarize the mematrium, where the blood then moves into brane to threshold and trigger the next Cardiovascular, Cardiac Cycle the left ventricle. action potential. Cardiovascular, Factors That • The left ventricle pumps blood into the • In most cardiac contractile cells, action Affect Blood Pressure aorta, which delivers it to the systemic potentials are characterized by a broad Cardiovascular, Cardiac Output organs and tissues. plateau phase that largely results from • Blood returns to the heart by way of the an increase in the cell membrane’s calCardiovascular, Intrinsic which carry it to the right Stanfield, Cindy. Principles venae of Humancavae, Physiology, Global Edition, Pearson Education, Limited, 2017. ProQuest Ebook Central,the http://ebookcentral.proquest.com/lib/mqu/detail.action?docID=5187887. cium permeability; flow of calcium Conduction System Created from mqu on 2023-08-09 00:38:07. 422 CHAPTER 13 The Cardiovascular System: Cardiac Function 13.6 Cardiac Output and Its Control, p. 412 • The volume of blood pumped by each ventricle per minute is the cardiac output (CO), which depends on the heart rate (HR) and stroke volume: CO = HR * SV. • The heart is regulated by sympathetic and parasympathetic neurons and hormones (extrinsic control) as well as by factors operating entirely within the heart (intrinsic control). • Heart rate, which is determined by the • End-diastolic volume is primarily de- firing frequency of the SA node, is entirely under extrinsic control. • Stroke volume is under extrinsic and intrinsic control and is affected by three major factors: ventricular contractility, end-diastolic volume, and afterload. • The influence of end-diastolic volume on stroke volume is the basis of Starling’s law of the heart, an example of intrinsic control of cardiac function. termined by end-diastolic pressure (preload). Cardiovascular, Cardiac Output Cardiovascular, Blood Pressure Regulation Regulation of Cardiac Output EXERCISES Multiple-Choice Questions 1. 2. Copyright © 2017. Pearson Education, Limited. All rights reserved. 3. 4. 5. 6. Minimum aortic pressure during the cardiac cycle is attained a) Immediately after closure of the aortic semilunar valve. b) Immediately before opening of the aortic semilunar valve. c) Immediately before opening of the atrioventricular valves. d) In mid-diastole. e) At the end of systole. The first heart sound occurs when the atrioventricular valves close; thus it marks a) The end of the ejection period. b) The beginning of the ejection period. c) The beginning of systole. d) The beginning of isovolumetric contraction. e) Both c and d are true. If you know end-diastolic volume, the only other thing you need to know to determine stroke volume is a) Afterload. b) Ventricular contractility. c) End-systolic volume. d) Heart rate. e) Cardiac output. As a result of Starling’s law, stroke volume should increase following an increase in a) Mean arterial pressure. b) Heart rate. c) Sympathetic activity. d) Afterload. e) Preload. c) Mitral and pulmonary valves. d) Mitral and tricuspid valves. e) Pulmonary and tricuspid valves. 7. Which of the following structures contributes to the pumping action of the heart? a) Epicardium b) Myocardium c) Endocardium d) Both a and c e) None of the above 8. The second heart sound occurs when the semilunar valves close; thus it marks a) The end of the ejection period. b) The beginning of the ejection period. c) The beginning of systole. d) The beginning of isovolumetric contraction. e) Both c and d are true. 9. The QRS complex of the ECG is due to a) Atrial depolarization. b) Atrial repolarization. c) Ventricular depolarization. d) Ventricular repolarization. e) Opening of the AV valves. 10. To trigger a heartbeat, an impulse travels from the a) Left atrium to the SA node. b) Right atrium to the SA node. c) AV node to the SA node. d) AV node through the bundle of His. e) Bundle of His to the left atrium. Sympathetic and parasympathetic input to the SA node influences a) Ventricular filling time. b) Ventricular contractility. c) Afterload. d) Atrial contractility. e) All of the above. 11. Which of the following is most likely to cause a decrease in the stroke volume of the left ventricle? a) An increase in mean arterial pressure b) An increase in end-diastolic pressure c) An increase in end-diastolic volume d) An increase in the activity of sympathetic nerves to the heart e) An increase in central venous pressure The atrioventricular valves of the heart include the a) Aortic and pulmonary valves. b) Aortic and tricuspid valves. 12. Left ventricular pressure and aortic pressure are virtually identical during a) Isovolumetric contraction. b) Isovolumetric relaxation. c) Diastole. d) Systole. e) The ejection period. Objective Questions 13. Heart rate is normally determined by the action potential frequency in the (SA/AV) node. 14. According to Starling’s law, stroke volume should increase if end-diastolic volume (increases/decreases). 15. Heart rate is determined entirely by the inherent action potential frequency in cells of the SA node, with no external influences. (true/false) 16. The pulmonary arteries carry (deoxygenated/oxygenated) blood to the lungs. 17. An estimate of the time of conduction through the (SA/AV) node is determined by the P-R interval. 18. (Isovolumetric contraction/Ejection) occurs immediately after diastole. 19. The maximum aortic pressure during the cardiac cycle is called (diastolic/systolic) pressure. 20. The papillary muscles relax during ventricular contraction. (true/false) 21. Stroke volume and termine cardiac output. completely de- 22. If end-diastolic volume does not change but end-systolic volume decreases, stroke volume (increases/decreases). 23. If end-diastolic volume does not change but end-systolic volume decreases, ejection fraction (increases/decreases). 24. If sympathetic and parasympathetic inputs are constant and end-diastolic volume increases, contractility of the ventricular myocardium increases. (true/false) 25. The red color of erythrocytes is due to the presence of . Stanfield, Cindy. Principles of Human Physiology, Global Edition, Pearson Education, Limited, 2017. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/mqu/detail.action?docID=5187887. Created from mqu on 2023-08-09 00:38:07.