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HUMAN ANATOMY & PHYSIOLOGY CARDIOVASCULAR SYSTEM Chapter 15 Notes HOLE’S HA&P | CHAPTER FIFTEEN OBJECTIVES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Discuss the functions of the organs of the cardiovascular system. Distinguish between the various coverings of the heart and the layers that compose the wall of the heart. Identify and locate the major parts of the heart and discuss the function of each part. Trace the pathway of the blood through the heart and the vessels of coronary circulation. Describe the cardiac cycle and explain how heart sounds are produced. Identify the parts of a normal ECG pattern and discuss the significance of this pattern. Explain control of the cardiac cycle. Compare the structures and functions of the major types of blood vessels. Describe how substances are exchanged between blood in capillaries and the tissue fluid surrounding body cells. Explain how blood pressure is produced and controlled. Describe the mechanisms that aid in returning venous blood to the heart. Compare the pulmonary and systemic circuits of the cardiovascular system. Identify and locate the major arteries. PART ONE 15.1-15.2 General Characteristics of the Cardiovascular System Cardio Vascular CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 1 LOCATION OF THE HEART IN THE THORACIC CAVITY The heart is a cone-shaped organ approximately the size of a fist and is located within the mediastinum, or medial cavity, of the thorax. It is flanked laterally by the lungs, posteriorly by the vertebral column, and anteriorly by the sternum. Its more pointed apex extends slightly to the left and rests on the diaphragm, approximately at the level of the fifth intercostal space. Its broader base, from which the great vessels emerge, lies beneath the second rib and points toward the right shoulder. In situ, the right ventricle of the heart forms most of the anterior surface. 1. The drawing at the right shows the heart within the chest cavity. Color the following parts on the diagram. Pericardium-covered heart (A) Superior vena cava (B) Pulmonary trunk (C) Pulmonary artery (D) Pulmonary vein (E) Aortic arch (F) Thoracic aorta (G) Trachea (H) Esophagus (I) THE WALL OF THE HEART The heart is enclosed within a double – walled fibrous sac called the pericardium. The thin visceral pericardium, or epicardium, which is closely applied to the heart muscle, reflects downward at the base of the heart to form its companion serous membrane, the outer, loosely applied parietal pericardium, which is attached at the heart apex to the diaphragm. Serous fluid produced by these membranes allows the heart to beat in a relatively frictionless environment. The serous parietal pericardium lines the loosely fitting superficial fibrous pericardium composed of dense connective tissue. Inflammation of the pericardium, pericarditis, causes painful adhesions between the serous pericardial layers. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 2 These adhesions interfere with heart movements. The wall of the heart is composed primarily of cardiac muscle – the myocardium – which is reinforced internally by a dense fibrous connective tissue network. The endocardium is the thin, inner lining of the heart. It is composed of simple squamous epithelium and some connective tissue. The endocardium is continuous with the inner lining of the blood vessels. 2. The drawing at the right shows the wall of the heart and the pericardium. Color the following parts on the diagram. Endocardium (A) Myocardium (B) Visceral Pericardium (C) Pericardial cavity (D) Parietal pericardium (E) Fibrous pericardium (F) 3. What is the covering around the heart called? ___________________________ 4. What is the function of the fluid – filled sac surrounding the heart? _____________________________________________________________ 5. Identify the layer of the heart wall (EPIcardium, MYOcardium, or ENDOcardium) described below. ______ Outer layer ______ Thick muscular layer ______ Continuous with the inner lining of blood vessels ______ Innermost layer ______ Also called visceral pericardium ______ Middle layer ______ Composed of simple squamous epithelium & some connective tissue CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 3 HEART CHAMBERS & VALVES The heart is divided into four chambers; two superior atria and two inferior ventricles, each lined with a thin serous lining called the endocardium. The septum that divides the heart longitudinally is referred to as the interatrial or interventricular septum, depending on which chambers it separates. Functionally, the atria are receiving chambers and are relatively ineffective as pumps. Blood flows into the atria under low pressure from the veins of the body. The right atrium receives relatively oxygen-poor blood from the body via the superior and inferior vena cava. Four pulmonary veins deliver oxygen-rich blood from the lungs to the left atrium. The inferior thick – walled ventricles, which form the bulk of the heart, are the discharging chambers. They force blood out of the heart into the large arteries that emerge form its base. The right ventricle pumps blood into the pulmonary trunk, which routes flood to the lungs to be oxygenated. The left ventricle discharges blood into the aorta, from which all systemic arteries of the body diverge to supply the body tissues. Four valves enforce a one – way blood flow through the heart chambers. The atrioventricular (AV) valves, located between the atrial and ventricular chambers on each side, prevent backflow into the atria when the ventricles are contracting. The left atrioventricular valve, also called the mitral or bicuspid valve, consists of two cusps, or flaps, of endocardium. The right atrioventricular valve, the tricuspid valve, has three cusps. Tiny white collagenous cords called the chordae tendineae (literally, heart strings) anchor the cusps to the ventricular walls. The chordae tendineae originate from small bundles of cardiac muscle, called papillary muscles, project from the myocardial wall. When blood is flowing passively into the atria and then into the ventricles during diastole (the period of ventricular relaxation), the atrioventricular valve flaps hang limply in the ventricular chambers and then are carried passively toward the atria by the accumulating blood. When the ventricles contract (systole) and compress the blood in their chambers, the intraventricular blood pressure rises causing the valve flaps to be reflected superiorly, which closes the AV valves. The chordate tendineae, pulled taut by the contracting papillary muscles, anchor the flaps in a closed position preventing backflow into the atria during ventricular contraction. If unanchored, the flaps would blow upward into the atria rather like an umbrella being turned inside out by a strong wind. The second set of valves, the pulmonary and aortic semilunar valves, each composed of three pocket-like cusps, guards the bases of the two large arteries leaving the ventricular chambers. The valve cusps are forced open and flatten against the walls of the artery as the ventricles discharge their blood into the large arteries during systole. However, when the ventricles relax, blood flows backward toward the heart and the cusps fill with blood, closing the semilunar valves and preventing arterial blood form reentering the heart. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 4 6. The drawing below shows the internal structures of the heart and the great vessels attached to the heart. Color the following parts on the diagram. 7. What is the function of the valves inside the heart? _____________________________________________________________ _____________________________________________________________ 8. Complete the following by filling in the blanks with the correct heart valve. The _________________________ prevents backflow of blood from the right ventricle into the right atrium. The _________________________ prevents back flow of blood from the left ventricle into the left atrium. The _________________________ prevents back flow of blood from the aorta into the left ventricle. The _________________________ prevents back flow of blood from the pulmonary trunk into the right ventricle. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 5 9. Describe what happens during: a. Diastole.________________________________________________ _______________________________________________________ b. Systole._________________________________________________ ________________________________________________________ 10. Identify the parts on the following diagrams. 1. __________________________ 2. __________________________ 3. __________________________ 4. __________________________ 5. __________________________ 6. __________________________ 7. __________________________ 8. __________________________ 9. __________________________ 10.__________________________ 11.__________________________ 12.__________________________ CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 6 11. Identify the parts on the following diagrams. 1. __________________________ 2. __________________________ 3. __________________________ 4. __________________________ 5. __________________________ 6. __________________________ 7. __________________________ 8. __________________________ 9. __________________________ 10.__________________________ 11.__________________________ 12.__________________________ 13.__________________________ 14.__________________________ CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 7 12. Color the following parts on the diagram below. Deoxygenated blood (A) Capillary blood (B) Oxygenated blood (C) Systemic circulation (D) Pulmonary circulation (E) The heart functions as a double pump. The right side serves as the pulmonary circulation pump, shunting the carbon dioxide – rich blood entering its chambers to the lungs to unload carbon dioxide and pick up oxygen, and then back to the left side of the heart. The function of this circuit is strictly to provide for gas exchange. The second circuit, which carries oxygen – rich blood from the left heart through the body tissues and back to the right heart is called the systemic circulation. It supplies the functional blood supply to all body tissues. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 8 13. Trace the path of blood through the heart by coloring the arrows on the diagram below. The shaded arrows show the path of deoxygenated blood. Use blue to color the shaded arrows. The other arrows show the path of oxygenated blood. Use red to color these arrows. 14. Identify the type of blood (Oxygenated or Deoxygenated) carried or pumped by each of the following structures. Use the drawing in the previous question for help. ______ Aorta ______ Inferior vena cava ______ Left atrium ______ Left ventricle ______ Pulmonary trunk/arteries ______ Pulmonary veins ______ Right atrium ______ Right ventricle ______ Superior vena cava CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 9 15. Identify the heart chambers represented by the numbers in the drawing from the previous question. 1.________________________ 3.__________________________ 2.________________________ 4.__________________________ 16. Use the word list below to complete the following. Aorta Inferior vena cava (IVC) Left atrium Left ventricle Pulmonary arteries Pulmonary veins Right atrium Right ventricle Superior vena cava (SVC) The _______________ and ______________ carry blood into the right atrium. The _________________________ pumps blood into the right ventricle. The _________________________ pumps blood into the pulmonary trunk. The _________________________ carry blood to the lungs. The _________________________ carry blood to the left atrium. The _________________________ pumps blood into the left ventricle. The _________________________ pumps blood into the aorta. The _________________________ carries blood to the body. 17. What is an ―Auricle? 18. Strong, fibrous strings that attach to the cusps of the tricuspid valve are called: CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 10 PART TWO 15.4 BLOOD VESSELS Closed circuit… Misc. Arteries Arterioles Capillaries Venules CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 11 Veins 19. Trace a drop of blood through the body and heart! a. Aortic Valve b. Arteries c. Arterioles d. Bicuspid valve e. Capillaries f. Left Atrium g. Left Ventricle h. Lung i. Pulmonary Trunk (arteries) j. Pulmonary Valve k. Pulmonary Veins l. Right Atrium m. Right Ventricle n. Tricuspid Valve o. Veins p. Vena Cavas q. Venules CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 12 BLOOD SUPPLY TO THE HEART ITSELF It is a muscle… and all muscles need a blood supply! Coronary Arteries Thrombus or Embolus Myocardial Infarction (MI) RETURN OF VENOUS BLOOD TO THE HEART A SMALL PRESSURE GRADIENT DRIVES BLOOD TOWARD THE HEART Blood flows from regions where its mechanical energy is high to regions where it is low. When we are in a recumbent position, most of this energy is in the form of pressure. As blood passes through the narrow arterioles and capillaries, the pressure falls substantially. In many venules, blood pressure is around 15 mm Hg. In the atria, the average pressure is close to 0 mm Hg. It follows that there is a small but definite pressure gradient available to force blood back to the heart. The fact that this small gradient (approximately 15 mm Hg) is sufficient to drive large volumes of blood demonstrates the low resistance of the venous pathway. Even veins that appear to be collapsed have a low resistance because the apparent ―creases‖ in the vessel are never really flat; they always leave some space that can be easily traversed by circulating blood. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 13 1. The diagram below shows the pressure gradient discussed in the above paragraph. Color the following diagram. Use Blue for A, Red for C, and Purple for D. 2. What happens to the pressure as blood moves from the arteries into the capillaries? 3. What happens to the pressure as blood moves form through the capillaries and into the veins? 4. Explain how the small pressure gradient between aids in the return of blood to the heart. MUSCLE CONTRACTION PUSHES VENOUS BLOOD In addition to pressure gradients, there are other mechanisms that aid venous return of blood to the heart. These include ―pumping actions‖ of noncardiac muscles as well as movements of the heart itself, and they depend on the valves in the veins, which point in the direction of the heart. This orientation ensures a forward flow toward the heart: blood flowing forward forces the valves open; backflow snaps them shut. The picture below shows this action in a vein lodged between two skeletal muscles. When the muscles are relaxed, blood flows forward because of the pressure gradient described above, and the vein fills with blood. The contracting muscles squeeze on the vein and force blood in all directions. Blood flowing backward closes the bottom valve, but forward-flowing blood keeps the upper valve open so that blood spurts in the forward direction. When the muscle relaxes, there is no longer any external force pushing on the venous walls: the pressure gradient from below (farthest from the heart) forces blood flow in the forward direction, opening the lower valve and reestablishing the initial condition. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 14 Thus, each time the muscle contracts and relaxes a spurt of venous blood is sent toward the heart. This action is called the muscle pump. A good illustration of the importance of the muscle pump in exercise is provided when a runner remains motionless just after finishing a strenuous race. His cardiac output is still high and his capillaries and small blood vessels are still dilated in response to the exercise. Without the muscle pump the veins are quickly drained, venous return to the heart decreases, and the cardiac output may falter sufficiently to compromise the blood supply to the brain. Fainting can be avoided if the runner continues mild exercise for a few minutes. 5. What causes the valves in the veins to open? 6. What causes the valves in the veins to close? 7. Describe how the muscle pump works. 8. A runner who remains motionless after completing a strenuous race may faint. Why? 9. Color the following parts on the diagram below. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 15 10. Examine the cross section of an artery and vein at the right. Which letter represents the artery?_____ How do you know this is an artery? ____________________________ Which letter represents the vein?_____ How do you know this is the vein? ____________________________ 11. Use the key below to identify the blood vessel being described. A. Arteries B. Arterioles C. Capillaries D. Venules E. Veins ______ Efferent blood vessels ______ Carry blood away from ______ Walls consist of 3 layers ______ Walls 1 cell layer thick ______ Have valves ______ Branch to form arterioles ______ Converge to form veins ______ Provide large surface area for exchange of materials ______ Afferent blood vessels ______ Carry blood to the heart heart ______ Have the thickest walls ______ Walls consist of only endothelium ______ Branch to form capillaries ______ Converge to form venules ______ Smallest, most numerous b.v.s ______ Site of diffusion 12.What factors are involved in the movement of blood to the heart? 13.What is the role of valves in the veins? 14.Explain what goes wrong when varicose veins appear on legs. 15.How can you tell by simple observation whether bleeding is arterial or venous? CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 16 16. Match the artery with the correct letter from the diagram. ______ Abdominal aorta ______ Aorta ______ Brachiocephalic ______ Left axillary artery ______ Left common carotid artery ______ Left common iliac artery ______ Left external iliac artery ______ Left subclavian artery ______ Right axillary artery ______ Right common carotid artery ______ Right common iliac artery ______ Right external iliac artery ______ Right subclavian artery ______ Thoracic aorta 17. Match the vein with the correct letter from the diagram. ______ Brachiocephalic vein ______ Inferior vena cava ______ Left common iliac vein ______ Left external iliac vein ______ Left subclavian vein ______ Right common iliac vein ______ Right external iliac vein ______ Right external jugular vein ______ Right subclavian vein ______ Superior vena cava CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 17 18. Match the artery or vein with the correct letter from the diagram. ______ Abdominal aorta ______ Aorta ______ Common carotid artery ______ Common iliac artery ______ Common iliac vein ______ External iliac artery ______ External iliac vein ______ External jugular vein ______ Inferior vena cava ______ Subclavian artery ______ Subclavian vein ______ Superior vena cava ______ Thoracic aorta CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 18 PART THREE 15.3 HEART ACTIONS Cardiac Cycle Systole Diastole CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 19 THE FIVE PERIODS OF THE CARDIAC CYCLE ATRIAL CONTRACTION Atrial contraction is signaled by the P wave of the ECG. As atrial pressure rises, blood is thrust into the ventricles through the open AV valves. These valves are open (as they have been throughout the diastole) because pressure in the atrium is higher than pressure in the quiescent ventricle. Blood enters the ventricle but cannot leave because the aortic valves are closed (pressure in the aorta is greater than the pressure in the ventricle). Note that the resulting volume increase on the ventricular volume curve appears as a small ―bump.‖ The atrium serves as a ―booster‖ pump, but its contribution to ventricular filling is small; most of the ventricular filling occurred earlier, when both atrium and ventricle were at rest. When the heart rate goes up, as in exercise, there is less time between beats for filling, and the atrial contribution becomes more significant. ISOVOLUMETRIC VENTRICULAR CONTRACTION Now the impulse invades the ventricles (QRS in the ECG), and, after a short delay, they begin to contract. This is the beginning of systole. Ventricular pressure builds up steeply and quickly exceeds atrial pressure. The AV valves snap shut, producing the first heart sound – ―Lupp or Lub.‖ Following closure of the AV valves, ventricular pressure continues to rise steeply until it exceeds aortic pressure. Pressure rises rapidly because both sets of heart valves are closed. The heart continues to contract, but there is no place for the blood to go to relieve the ascending pressure. (Contraction of the heart during this period is similar to an isometric contraction in skeletal muscle.) During this period, the ventricular volume cannot change – note the flat horizontal trace on the ventricular volume curve. The constant ventricular volume is the reason for naming this period ―isovolumetric ventricular contraction.‖ VENTRICULAR EJECTION As soon as the ventricular pressure exceeds aortic pressure, the aortic valves are thrust open, and blood is ejected into the aorta. Pressure in the aorta begins to rise because blood is entering from the ventricles faster than it can leave through the smaller arteries. Prior to this time, pressure in the aorta had been falling because the aortic valves were closed; blood continued to leave the aorta through smaller arteries, but none could enter from the ventricle. Blood entering the ventricles is reflected in the ventricular volume curve, which drops precipitously as soon as ejection begins. Soon afterward, the contractile force of the ventricle wanes; the ventricular pressure ascent slows and begins to reverse while the initial rapid change in ventricular volume begins to level off. As the ventricles begin to repolarize (T wave of the ECG) and relax, the ventricular pressure curve crosses the aortic curve and goes below it. Shortly thereafter, the aortic valve snaps shut, producing a sharp ―Dup‖ sound (the second heart sound) and bringing the ventricular ejection period, as well as the period of systole, to an end. It also produces a bump notch on the aortic pressure curve. The aortic valve closure is not simultaneous with the crossover of the ventricular and aortic pressure curves because the blood flowing through the valves has an appreciable momentum (mass X velocity) in the direction of forward flow. Applying a force (pressure difference) in the opposite direction requires a small amount of time to stop or reverse the motion. (Imagine trying to stop a rolling automobile with a hand push in the opposite direction.) Notice that not all of the blood contained within the ventricle is ejected with each beat. The residual blood is almost equal to the amount ejected. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 20 ISOVOLUMETRIC VENTRICULAR RELAXATION Now, as in isovolumetric contraction, both valves are closed, and blood cannot enter or leave the ventricles. This time, however, the ventricular muscles relax; it is the beginning of diastole. Pressure falls precipitously, but ventricular volume does not change. Soon the ventricular pressure falls below atrial pressure, the AV valves open, and isovolumetric relaxation ends. VENTRICULAR FILLING In this period, atrial pressure is higher than ventricular pressure because blood continues to flow into the atrium from the pulmonary veins. Blood flows through the open AV valve from atrium to ventricle. Ventricle filling continues throughout diastole, not just when the atrium contracts. The ventricular volume curve during diastole shows that early ventricular filling is not prominent and that contraction of the atrium contributes only a minor portion to the ventricular contents. Toward the end of this period, atrial contraction ensues, and this period, as well as diastole, ends with closure of the AV valves. DIRECTIONS FOR COLORING THE DIAGRAM ON NEXT PAGE… 1. Pick colors for each item listed in the key below. Use red for Blood (F). o Left atrium (A) o AV valve (B) o Left ventricle (C) o Aortic valve (D) o Aorta (E) o Blood (F) use red 2. Using the key in #1: a. Color the titles for 1 – 5 and all the labeled structures in each heart diagram. Color the heart sounds and the sound bars surrounding the relevant valve. b. Color the pressure graph and refer to the relevant period in the cardiac cycle shown at the top. c. Color the volume graph and refer to the relevant period in the cardiac cycle shown at the top. 3. Pick a color, one not used in the key, to color the ECG graph. 4. Pick a color, one not used in the key, to color the bottom numbers representing the time intervals. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 21 CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 22 CARDIAC CONDUCTION SYSTEM SA Node Atrial Syncytium Junctional Fibers AV Node AV Bundle Bundle Branches Purkinje Fibers Ventricular Syncytium CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 23 HEART SOUNDS Lub Dup ELECTROCARDIOGRAPHY (ECG/ EKG) General Description P Q R S T Heart Rate CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 24 15.5 BLOOD PRESSURE Arteriole Blood Pressure Factors affecting arterial blood pressure Heart Action Blood Volume Peripheral Resistance Viscosity Control of Blood Pressure… p. 585-587 BP = CO x PR (recall: CO = SV x HR) & (SV = EDV-ESV) Mechanical—Frank -Starling law of the heart: Increased stretch (preload) = increased strength of contraction Neural—Increased sympathetic innervation increases the force of contraction which increases the percentage of EDV pumped out in a single beat. Chemical—Epinephrine increases heart rate. Carbon Dioxide, Oxygen, H+ ions, Nitric Oxide, Angiotensin, Bradykinin Fear, anger, physical exercise, rise in external temperature CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 25 Questions 1. Match the description with the correct conduction system component. Use the key provided to indicate your answers. A. SA node B. AV node C. AV bundle & branches D. Purkinje fibers ______ Sinoatrial node ______ Located in the right atrium inferior to the entrance of the sup. vena cava ______ Atrioventricular node ______ Located in the lower atrial septum at the junction of atria and ventricles ______ Located within the interventricular septum ______ Located within the walls of the ventricles ______ Pacemaker ______ Provides the stimulus for contraction ______ Sets the rate of depolarization for heart as whole ______ Delays conduction of the impulse 2. Listed below are the events that cause the heart to contract. Put the steps in the correct order. ______ Depolarization of the SA node ______ Impulse passes along the Purkinje fibers ______ Impulse spreads throughout the atria ______ AV node receives impulse ______ Impulse passes through the AV bundle ______ AV node delays conduction of the impulse for approximately 0.1 sec. ______ Atria contract ______ Impulse passes through the bundle branches ______ Ventricles contract 3. Identify the ECG wave (P, QRS, or T) described in each of the following: ______ Atrial depolarization ______ Depolarization wave travels from the SA node to the AV node ______ Depolarization travels along AV bundle, bundle branches, Purkinje fibers ______ Ventricular depolarization ______ Ventricular repolarization ______ Causes atria to contract ______ Causes ventricles to contract ______ Atria empty ______ Ventricles empty CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 26 ______ Atria fill ______ Ventricles fill 4. Match the ECG component and event with the correct letter from the diagram at the right. ______ T wave ______ P wave ______ QRS complex ______ Depolarization of ventricles ______ Repolarization of ventricles ______ Depolarization of atria ______ Causes contraction of atria ______ Causes contraction of ventricles ______ Ventricles empty ______ Ventricles fill ______ Atria empty ______ Atria fill 5. How is the pressure on in the right side of the heart different from the pressure in the left side of the heart? _____________________________________________________________ Why does this difference exist? ____________________________________ _____________________________________________________________ 6. The opening and closing of the valves results from the changes in pressure within the heart. Match the event with the correct cause. A. AV valves close B. AV valves open C. Semilunar valves open D. Semilunar valves close ______ Pressure inside the ventricles is higher than the pressure inside the atria ______ Pressure inside the larger arteries is higher than the pressure inside the ventricles ______ Pressure inside the large arteries is lower than the pressure inside the ventricles ______ Pressure inside the ventricles is lower than the pressure inside the atria CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 27 7. Identify the period of the cardiac cycle during which each of the following events occur. Use the key below to indicate your answers. 1. 2. 3. 4. 5. Atrial contraction Isovolumetric ventricular contraction Ventricular ejection Isovolumetric ventricular relaxation Ventricular filling ______ Signaled by the P wave of the ECG ______ Atria contract forcing blood into the ventricles ______ Signaled by the QRS complex of the ECG ______ Ventricles begin to contract ______ Systole begins ______ Pressure inside the ventricles increases until the pressure in the ventricles exceeds the pressure inside the atria ______ Pressure inside the ventricles is lower than the pressure inside the aorta ______ AV valves close ______ Lupp (Lub) heart sound produced ______ Ventricular volume cannot change ______ Pressure inside ventricles exceeds pressure inside the aorta ______ Semilunar valves (aortic) open ______ Contraction of the ventricles forces blood out of the ventricles into the aorta ______ Volume in the ventricles decreases ______ Semilunar valves snap shut ______ Dup heart sound produced ______ Ventricles relax ______ Diastole begins ______ Pressure in the ventricles decreases ______ AV valves open ______ Pressure in the atria is higher than the pressure in the ventricles ______ Blood flows from the atria into the ventricles ______ Ventricular volume increases CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 28 8. Indicate if each of the following events occurs during Systole or Diastole. ______ Ventricles contract and empty ______ Ventricles relax and fill ______ Atria contract and empty ______ Atria relax and fill ______ AV valves close ______ Semilunar valves close 9. What would happen if the length of the quiescent (ventricular relaxation) period decreased? _____________________________________________________________ _____________________________________________________________ 10. Identify the heart sound (Lub or Dup) described in each of the following. ______ First heart sound ______ Second heart sound ______ Longer, louder sound ______ Shorter, sharper sound ______ Associated with closure of the AV valves ______ Associated with closure of the semilunar valves 11. Define cardiac output. _____________________________________________________________ _____________________________________________________________ 12. What two factors determine cardiac output? _____________________________________________________________ _____________________________________________________________ CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 29 13. Complete the following equation by filling in the missing parts. 14. What is the average heart rate for an adult at rest? ____________________ 15. What does ―bpm‖ represent? ______________________________________ 16. Define stroke volume. _____________________________________________________________ 17. What is the average stroke volume for an adult at rest? _________________ 18. Explain the three primary factors regulating Stroke Volume. (p. 585-586) Mechanical: Neural: Chemical: 19. An increase in venous blood returning to the heart will __________________ heart rate. 20. In general, more blood entering the ventricles causes an _______________ in ventricular contraction resulting in an ______________ in cardiac output. 21. Stimulation of parasympathetic neurons causes the release of _________________________ which _________________ heart rate. 22. Stimulation of sympathetic neurons causes the release of _________________________ and ______________________ which _________________________ heart rate. CARDIOVASCULAR SYSTEM | HA&P Notes Chapter 15 page 30