Chapter 18: The Heart – Flashcards
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The inner lining of the heart
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Endocardium.
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Heart muscle
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Myocardium.
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Serous layer covering the heart muscle.
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Epicardium.
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The outermost layer of the serous pericardium.
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Parietal layer.
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The pacemaker of the heart.
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SA node.
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Found in the interventricular septum.
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AV bundle.
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Network found in the ventricular myocardium.
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Purkinje fibers.
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The point in the conduction system of the heart where the impulse is temporarily delayed.
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AV node.
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Prevents backflow into the left ventricle.
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Aortic valve.
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Prevents backflow into the right atrium.
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Mitral valve.
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Prevents backflow into the right ventricle.
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Pulmonary valves.
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AV valve with two flaps.
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Mitral valve.
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AV valve with three flaps.
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Tricuspid valve.
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Heart muscle is deprived of oxygen.
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Ischemia.
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Death of heart muscle cells.
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Infraction.
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A condition of rapid and irregular or out-of-phase contraction of heart muscle cells.
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Fibrillation.
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An abnormal pacemaker.
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Ectopic focus.
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Total heart relaxation.
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Quiescent period.
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Normal heart sounds are caused by what?
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Closure of the heart valves.
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What does NOT occur when the semilunar valves are open?
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Ventricles are in diastole.
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Hemorrhage with a large loss of blood causes
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a lowering of blood pressure due to change in cardiac output.
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The left ventricular wall of the heart is thicker than the right wall in order to
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pump blood with greater pressure.
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Damage to what node is referred to as heart block?
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AV node.
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The P wave of a normal electrocardiogram indicates
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atrial depolarization.
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Blood within the pulmonary veins returns to the
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left atrium.
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Small muscle masses attached to the chordae tendineae are the
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papillary muscles.
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The term for pain associated with deficient blood delivery to the heart that may be caused by the transient spasm of coronary arteries is
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angina pectoris.
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To auscultate the aortic semilunar valve, you would place your stethoscope in the
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second intercostal space to the right of the sternum.
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The source of blood carried to capillaries in the myocardium would be the
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coronary arteries.
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The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it
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pumps blood against a greater resistance.
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Which of the following factors does NOT influence heart rate?
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Skin color.
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Which of the following is NOT an age-related change affecting the heart?
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Thinning of the valve flaps.
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If cardiac muscle is deprived of its normal blood supply, damage would primarily result from
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decreased delivery of oxygen.
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If the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells
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tetanic contractions might occur, which would stop the hearts pumping action.
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Norepinephrine acts on the heart by
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causing threshold to be reached more quickly.
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If the vagal nerves to the heart were cut, the result would be that
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the heart rate would be increased by about 25 beats per minute.
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Foramen ovale
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the two atria in the fetal heart.
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Which vessel of the heart receives blood during right ventricular systole?
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Pulmonary trunk.
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Which of these vessels receives blood during ventricular systole?
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Both the aorta and pulmonary trunk.
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Which is NOT part of conduction system of the heart?
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AV valve.
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The tricuspid valve is closed
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when the ventricle is in systole.
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When viewing a dissected heart, it is easy to visually discern the right and left ventricles by
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noticing the thickness of the ventricle walls.
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Select the correct statement about the heart valves.
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the AV valves are supported by chordae tendineae so that regurgitation of blood into the atria during ventricular contraction does not occur.
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Select the correct statement about the function of myocardial cells.
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The entire heart contracts as a unit or it does not contract at all.
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Select the correct statement about the structure of the heart wall.
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The myocardium is the layer of the heart that actually contracts.
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Compared to skeletal muscle, cardiac muscle
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has gap junctions that allow it to act as a functional syncytium.
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During the period of ventricular filling
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blood flows passively through the atria and the open AV valves into the ventricles.
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The second heart sound is heard during which phase of the cardiac cycle?
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Isovolumetric relaxation.
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The time of day most hazardous for heart attacks is
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morning.
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If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid,
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threshold is reached more quickly and heart rate would increase.
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Select the correct statement about cardiac output.
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A slow heart rate increases end diastolic volume, stroke volume, and force of contraction.
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During contraction of heart muscle cells..
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some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores.
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Isovolumetric contraction
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refers to the short period during ventricular systole when the ventricles are completely closed chambers.
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Commotio cordis is heart failure due to what?
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A relatively mild blow to the chest that occurs during a vulnerable interval (2 ms) when the heart is repolarizing.
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The enlarged coronary vessel outside the heart that empties blood into the right atrium is the
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coronary sinus.
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What structure in the fetal heart allows blood to flow from the right atrium directly to the left atrium?
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Foramen ovale.
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The ECG T wave interval represents
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ventricular repolarization.
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Cardiac output (CO)=
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Heart rate (HR) * sv
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What layer of the serous pericardium membrane covers the heart?
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Visceral layer.
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What valve of the heart has three valves with chordae tendineae?
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Tricuspid valve.
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What valves of the heart have NO chordae tendineae attached?
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Aortic and pulmonary valves.
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The myocardium receives its blood supply from the coronary arteries.
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True.
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Anastomoses among coronary arterial branches provide collateral routes for blood delivery to the heart muscle.
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True.
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Congestive heart failure means that the pumping efficiency of the heart is depressed so that there is inadequate delivery of blood to body tissues.
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True.
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Tissues damaged by myocardial infarction are replaced by connective tissue.
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True.
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The left side of the heart pumps the same volume of blood as the right.
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True.
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Chronic release of excess thyroxine can cause a sustained increase in heart rate and a weakened heart.
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True.
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Trabeculae carneae are found in the ventricles and never the atria.
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True.
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As pressure in the aorta rises due to atherosclerosis, more ventricular pressure is required to open the aortic valve.
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True.
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Proxysmal atrial tachycardia is characterized by bursts of atrial contractions with little pause between them.
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True.
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A 14-year-old girl undergoing a physical examination prior to being admitted to summer camp was found to have a loud heart diastolic murmur at the second intercostal space to the left side of the sternum. Explain the reason for the loud heart murmur associated with this girl's condition.
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The heart murmur is due to incomplete closing of the pulmonary valve.
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A man enters the hospital complaining of chest pain. His history includes smoking, a stressful job, a diet heavy in saturated fats, lack of exercise, and high blood pressure. Although he is not suffering from a heart attack, his doctor explains to him that a heart attack is quite possible. What did the chest pain indicate? Why is this man a prime candidate for a heart attack?
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His symptoms indicate angina pectoris, possibly due to either atherosclerosis or stress-induced spasms of the coronary arteries. If the arteries are occluded (atherosclerosis), the heart muscle could be deprived of blood, and therefore oxygen. A heart attack could occur if the coronary vessels experience further (or progressive) occlusion.
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An older woman complains of shortness of breath and intermittent fainting spells. Her doctor runs various tests and finds that the AV node is not functioning properly. What is the suggested treatment?
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The suggested treatment is surgery to implant an artificial pacemaker.
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An angiocardiogram was performed on an infant who had symptoms of breathlessness and it was found that he had a patent ductus arteriosus. Discuss the location and function of the ductus arteriosus in the fetus and relate it to the reason for the infant's breathlessness.
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The ductus arteriosus is a shunt between the pulmonary trunk and the aorta in the fetus, which normally closes at birth. Breathlessness is due to the mixing of oxygenated and deoxygenated blood because the connection between the aorta and the pulmonary trunk remains slightly open.
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A patient takes a nitroglycerin tablet sublingually for chest pain. Nitroglycerin acts directly on smooth muscle, producing relaxation and vessel dilation. How would this relieve chest pain?
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Angina pectoris is thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium, with resulting decreased oxygen being delivered to the cells. Because nitroglycerin acts as a vasodilator, blood flow is increased, promoting the delivery of oxygen to the cells.
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A patient was admitted to the hospital with chest pains. On admission, his pulse was 110 and blood pressure was 96/64. According to his history, his normal pulse rate is usually between 80 and 88 and his blood pressure runs from 120/70 to 130/80. Explain why these changes in BP and HR occur.
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Increased heart rate (measured by taking his pulse) without maintaining his normal blood pressure is suggestive of reduced stroke volume. Both a drop in blood volume and a weakened heart could cause this, but the chest pains suggest heart damage. Failure of compensating mechanisms to maintain blood pressure suggest a serious decline in cardiac output.
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A 55-year-old male was admitted to the hospital with heart failure. He complains of increasing shortness of breath on exertion and needing to sleep on three pillows at night. On physical assessment, the nurse determines that his ankles and feet are very swollen. Which of these symptoms reflect left-sided heart failure and which reflect right-sided heart failure?
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Because the heart is a double pump, each side can initially fail independently of the other. If the left side fails, pulmonary congestion occurs. The right side of the heart continues to propel blood to the lungs, but the left side does not adequately eject the returning blood into the systemic circulation. Thus, blood vessels in the lungs become engorged with blood, pressure within them increases, and fluid leaks from the circulation into the lung tissue, causing pulmonary edema. Shortness of breath and difficulty breathing in a prone position may occur.
If the right side of the heart fails, peripheral congestion occurs. Blood stagnates within body organs, and pooled fluids in the tissue spaces impair the ability of body cells to obtain adequate nutrients and oxygen and to rid themselves of wastes. Edema is most noticeable in the extremities (feet, ankles, and fingers).
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Asystole is the total absence of ventricular electrical activity. Explain why defibrillation would not be effective in this situation.
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Defibrillation is accomplished by electrically shocking the heart, which interrupts its chaotic twitching by depolarizing the entire myocardium. In this case, the ventricles are at a total standstill and defibrillation would not be effective.
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A patient is prescribed a calcium channel blocker to prevent angina (chest pain), by decreasing the demand for oxygen. Explain why.
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By preventing the influx of calcium ions into myocardial and vascular smooth muscle cells, calcium channel blockers inhibit the intracellular release of additional stores of calcium ions. A drug that inhibits the release of intracellular calcium ions decreases the force of myocardial contractility, thereby decreasing the oxygen demand.
