Human Physiology
15th Edition
ISBN: 9781259864629
Author: Fox, Stuart Ira
Publisher: Mcgraw-hill Education,
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Textbook Question
Chapter 13, Problem 9RA
Which of these statements is true?
a. The heart can produce a graded contraction.
b. The heart can produce a sustained contraction.
c. The action potentials produced at each cardiac cycle normally travel around the heart in circus rhythms.
d. All of the myocardial cells in the ventricles are normally in a refractory period at the same time.
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Why is it necessary to stimulate papillary muscles in the ventricle slightly earlier than the rest of the ventricular wall myocardium?
a. to assure rapid conduction speed of the action potential
b. to pull on AV valve cusps to prevent backflow
c. to assure blood will surge toward the semilunar valves
d. to assure coordinated contraction of the ventricular myocardium
The heart’s internal pacemaker beats by: a. an internal implant that sends an electrical impulse through the heart b. the excitation of cardiac muscle cells at the sinoatrial node followed by the atrioventricular node c. the excitation of cardiac muscle cells at the atrioventricular node followed by the sinoatrial node d. the action of the sinus
SA node is the main pacemaker of the heart. Why is the normal heart rate lower than the intrinsic firing rate of the SA node?
A. sympathetic inputs from the hypothalamus are slowing it down
B. parasympathetic inputs from medulla oblongata are slowing it down
C. there is inertia in heart muscle as it takes time for impulse to spread through all the cells
D. centrifugal inputs from the AV node are slowing it down
Chapter 13 Solutions
Human Physiology
Ch. 13 - State the components of the circulatory system...Ch. 13 - Prob. 1bCPCh. 13 - Prob. 2CPCh. 13 - Prob. 3CPCh. 13 - Describe how the rate of erythropoiesis is...Ch. 13 - Prob. 5aCPCh. 13 - Prob. 5bCPCh. 13 - Using a flow diagram (arrows), describe the...Ch. 13 - Use a flow diagram to describe the systemic...Ch. 13 - List the AV valves and the valves of the pulmonary...
Ch. 13 - Discuss how defective valves affect blood flow...Ch. 13 - Prob. 7bCPCh. 13 - Prob. 8aCPCh. 13 - Prob. 8bCPCh. 13 - Draw a figure to illustrate the pressure...Ch. 13 - Prob. 10aCPCh. 13 - Using a line diagram, illustrate a myocardial...Ch. 13 - Draw an ECG and label the waves. Indicate the...Ch. 13 - Draw a figure that shows the relationship between...Ch. 13 - Prob. 11cCPCh. 13 - Prob. 12aCPCh. 13 - Prob. 12bCPCh. 13 - Explain the functions of capillaries and describe...Ch. 13 - Prob. 14CPCh. 13 - Prob. 15CPCh. 13 - Identify normal and pathological causes of...Ch. 13 - Prob. 16bCPCh. 13 - Prob. 17aCPCh. 13 - Explain how the lymphatic system and the...Ch. 13 - Prob. 18CPCh. 13 - Prob. 1RACh. 13 - All arteries in the body contain oxygen-rich blood...Ch. 13 - The "lub," or first heart sound, is produced by...Ch. 13 - The first heart sound is produced at
Ch. 13 - Changes in the cardiac rate primarily reflect...Ch. 13 - Prob. 6RACh. 13 - Prob. 7RACh. 13 - The cells that normally have the fastest rate of...Ch. 13 - Which of these statements is true? a. The heart...Ch. 13 - Prob. 10RACh. 13 - Prob. 11RACh. 13 - Prob. 12RACh. 13 - Prob. 13RACh. 13 - Prob. 14RACh. 13 - Prob. 15RACh. 13 - During the phase of isovolumetric relaxation of...Ch. 13 - Peristaltic waves of contraction move fluid within...Ch. 13 - Describe how the pacemaker cells produce a...Ch. 13 - What characteristic of the SA node distinguishes...Ch. 13 - Compare the duration of the heart's contraction...Ch. 13 - Step by step, describe the pressure changes that...Ch. 13 - Can a detective valve be detected by an ECG? Can a...Ch. 13 - Describe the causes of the P, QRS, and T waves of...Ch. 13 - The lungs are the only organs that receive the...Ch. 13 - Prob. 25RACh. 13 - Prob. 26RACh. 13 - Prob. 27RACh. 13 - Prob. 28RACh. 13 - Prob. 29RACh. 13 - Prob. 30RACh. 13 - Prob. 31RACh. 13 - Prob. 32RACh. 13 - Prob. 33RACh. 13 - Prob. 34RACh. 13 - Prob. 35RACh. 13 - Prob. 36RACh. 13 - Prob. 37RACh. 13 - Prob. 38RACh. 13 - Prob. 39RACh. 13 - Prob. 40RACh. 13 - Prob. 41RACh. 13 - Prob. 42RA
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- PREDICT A patients mitral valve (left AV valve) does not close completely at the beginning of ventricular systole. What effect would this have on the cardiac cycle?arrow_forwardContraction of _______ drives the flow of blood through the aorta and pulmonary arteries. a. atria b. veins c. arterioles d. Ventriclesarrow_forwardDescribe the cardiac cycle.arrow_forward
- Which of the following is not true for conduction of the cardiac impulse? A. Action potentials propagate by current flow through gap junctions. B. Slow propagation occurs due to high longitudinal resistance. C. Slow propagation requires a slower (sustained) current source (i.e. Ca). D. Fast propagation occurs as a result of high intercellular conductance. E. All are true.arrow_forwardWhich of the following is true of propagation of longitudinal electrical flow in cardiac muscle. A. Current flows longitudinally from a region of depolarization through ryanodine receptors. B. Longitudinal current flows through inward rectifier potassium channels. C. This current can be detected at the body surface, if the source is large enough. D. A and B. E. All are true.arrow_forwardDuring the ventricular ejection phase of the normal human cardiac cycle, one option is correct: a. ejection takes less time than filling, in a resting human. b. the left ventricle diameter increases and the ventricle elongates from base to apex. c. papillary muscles close the atrioventricular valves. d. the chordae tendineae are relaxed. e. the apex beat is best felt in the anterior axillary line, fifth intercostal space.arrow_forward
- What is the correct order of events in the left ventricle during the systole phase of the cardiac cycle? a. Ventricular repolarization, ventricular relaxation, 2nd heart sound, AV valve opens, blood moves in b. QRS-complex, ventricular contraction, 2nd heart sound, aortic valve opens, blood moves out c. P-wave, increased ventricular pressure, 1st heart sound, aortic valve opens, blood moves in d. QRS complex, ventricular contraction, 1st heart sound, AV valve opens, blood moves out e. QRS complex, increased ventricular pressure, AV-valve closes, blood moves outarrow_forwardWhich of the following statement/s is/are not true regarding phases of cardiac cycle? A. Atrial systole is followed by ventricular systole. B. When the ventricles are in systole, the atria are in diastole. C. The atria continually receive blood from the veins. D. As pressure within the atria increases, the mitral valve is opened. E. All statements are true.arrow_forwardWhich of the following statements is true about the SA (sinoatrial) node? a. The action potential created by the pacemaker cells of the SA node directly stimulates the contractile cells of both the atria and ventricles. b. The rate of spontaneous depolarization of nodal cells is the fastest in the SA node. c. Pacemaker cells in the SA node form a pathway between the SA and AV nodes. d. The pacemaker cells, which establish the heart rate, are located only in the SA node.arrow_forward
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