Human Physiology: An Integrated Approach (8th Edition)
8th Edition
ISBN: 9780134605197
Author: Dee Unglaub Silverthorn
Publisher: PEARSON
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Textbook Question
Chapter 14.3, Problem 12CC
A drug that blocks all Ca2+ channels in the myocardial contractile cell membrane is placed in the solution around the cell. What happens to the force of contraction in that cell?
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A 65-year old man with heart failure is unable to climb a flight of stairs without experiencing dyspnea. After several years of therapy with carvedilol, captopril and furosemide, the therapeutic plan probably needs to change now. You empirically add digoxin to improve cardiac muscle contractility. Within 4 week he has a marked improvement in his symptoms. Which of the following best describes the main cellular action of digoxin that accounts for its ability to improve his cardiovascular function?
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Chapter 14 Solutions
Human Physiology: An Integrated Approach (8th Edition)
Ch. 14.1 - A cardiovascular system has what three major...Ch. 14.1 - What is the difference between (a) the pulmonary...Ch. 14.2 - Which is more important for determining flow...Ch. 14.2 - The two identical tubes below have the pressures...Ch. 14.2 - All four tubes below have the same driving...Ch. 14.2 - Two canals in Amsterdam are identical in size, but...Ch. 14.3 - What prevents electrical signals from passing...Ch. 14.3 - Prob. 8CCCh. 14.3 - Prob. 9CCCh. 14.3 - Compare the receptors and channels involved in...
Ch. 14.3 - If a myocardial contractile cell is placed in...Ch. 14.3 - A drug that blocks all Ca2+ channels in the...Ch. 14.3 - Which ions moving in what directions cause the...Ch. 14.3 - At the molecular level, what is happening during...Ch. 14.3 - Lidocaine is a molecule that blocks the action of...Ch. 14.3 - What does increasing K+ permeability do to the...Ch. 14.3 - A new cardiac drug called ivabradine selectively...Ch. 14.3 - Do you think that the Ca2+ channels in...Ch. 14.3 - What happens to the action potential of a...Ch. 14.3 - In an experiment, the vagus nerve, which carries...Ch. 14.4 - Name two functions of the AV node. What is the...Ch. 14.4 - Prob. 22CCCh. 14.4 - Occasionally an ectopic pacemaker {ktopos, out of...Ch. 14.4 - Prob. 24CCCh. 14.4 - Which chamberatrium or ventriclehas higher...Ch. 14.4 - Prob. 26CCCh. 14.4 - Prob. 27CCCh. 14.4 - Prob. 28CCCh. 14.4 - Prob. 29CCCh. 14.4 - Why does ventricular pressure shoot up suddenly at...Ch. 14.4 - Prob. 31CCCh. 14.4 - Prob. 32CCCh. 14.4 - A persons aortic valve opening has become...Ch. 14 - What contributions to understanding the...Ch. 14 - List three functions of the cardiovascular system.Ch. 14 - Prob. 3RQCh. 14 - Prob. 4RQCh. 14 - Prob. 5RQCh. 14 - Prob. 6RQCh. 14 - Prob. 7RQCh. 14 - Distinguish between the two members of each of the...Ch. 14 - Prob. 9RQCh. 14 - Prob. 10RQCh. 14 - What is the proper term for each of the following?...Ch. 14 - List the events of the cardiac cycle in sequence,...Ch. 14 - Prob. 13RQCh. 14 - Compare and contrast the structure of a cardiac...Ch. 14 - Prob. 15RQCh. 14 - Correlate the waves of an ECG with mechanical...Ch. 14 - Prob. 17RQCh. 14 - List and briefly explain four types of information...Ch. 14 - Define inotropic effect. Name two drugs that have...Ch. 14 - Prob. 20RQCh. 14 - Police Captain Jeffers has suffered a myocardial...Ch. 14 - Prob. 22RQCh. 14 - Prob. 23RQCh. 14 - Police Captain Jeffers in question 21 has an...Ch. 14 - Prob. 25RQCh. 14 - Prob. 26RQCh. 14 - Prob. 27RQCh. 14 - A person has a total blood volume of 5 L. Of this...
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- In a patient given a cardiac glycoside, important effects of the drug on the heart include which of the following? a) Increased force of contraction. b)Decreased atrioventricular conduction velocity c)Decreased ejection time d)Increased ectopic automaticityAll of the abovearrow_forwardThe muscle cells of a heart chamber work as a functional syncytium. In terms of heart function this means... A) All the cardiac muscle cells are controlled by one motor neuron, resulting in coordinated contraction. B) All the cardiac muscle cells are electrically connected by gap junctions, resulting in coordinated contraction. C) All the cardiac muscle cells are stimulated to contract by hormone release, resulting in near-coordinated contraction. D) All the cardiac muscle cells contract independently of each other (fibrillation).arrow_forwardWhat is the consequence of the prolonged plateau of depolarization in ventricular myocytes? a-it causes ventricular myocytes to contract for a longer time, allowing the ventricles time to empty b-it gives additional time for the atria to contract, filling the ventricles more completely c-it causes repolarization to be delayed which slows heart rate d-it allows the ventricles a moment to rest before completing contractionarrow_forward
- 1) A drug was applied to a person that blocked the pore/channel in the L-type calcium channel in cardiac muscle cells. The drug had no other effects. True/false: Cross-bridge cycling and tension production would occur normally in drug-treated fibers. 2) The plateau phase of a cardiac action potential is an absolute refractory period.True/false 3) If a heart lacked gap junctions, an organ-level contraction would occur.True/false 4) During a pacemaker potential, what is caused in neighboring muscle fibers when threshold potential is reached. Group of answer choices a)cross-bridge cycling b)Receptor potential c)An action potential d)A graded potentialarrow_forwarda) A consequence of the Frank-Starling law of the heart is that the outputs of the right and left ventricles match. Explain why this is important and how this match is made.b) The excitation-contraction matching mechanism within the heart muscle is different from that of the skeletal muscle. How might these differences be related to the difference between action potentials in cardiac muscle and skeletal muscle?arrow_forwardAnswer ALL parts of this question. In terms of heart failure there is a decrease in cardiac output. This is due to a contractile deficit in the individual cardiac myocytes. (a) Explain how this contractile deficit occurs. (b) What common cardiac problem is often associated with the changes in calcium handling often seen in cardiac cells of heart failure patients? Explain how this problem arises. (c) Describe the mechanism of action of levosimendan in the treatment of heart failure.arrow_forward
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