Human Biology: Concepts and Current Issues (8th Edition)
8th Edition
ISBN: 9780134042435
Author: Michael D. Johnson
Publisher: PEARSON
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Textbook Question
Chapter 8, Problem 6AWK
Ventricular fibrillation is a potentially fatal condition where the cells of the heart are no longer coordinated in their contractions. Why is it important that contraction of the heart muscle occurs nearly all at once?
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We analyzed the difference between the action potential of a cardiac contractile cell and an action potential in a neuron. Describe the physiological mechanisms behind the primary difference in the shape of these two action potentials. Why is this feature important to the normal workings of the heart?
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The entry of calcium into a ventricular muscle cell helps to maintain depolarization of the membrane during the plateau phase of the action potential, but this calcium also performs what other function?
Chapter 8 Solutions
Human Biology: Concepts and Current Issues (8th Edition)
Ch. 8 -
1. Who do you want to help you decide which...Ch. 8 - Do you think cost-effectiveness should be a part...Ch. 8 -
1. Why is it so important that the heart always...Ch. 8 - Compare and contrast the structures and functions...Ch. 8 - Prob. 3CRCh. 8 - Describe the function of the heart valves.Ch. 8 - Compare the functions of the pulmonary circuit and...Ch. 8 -
6. Describe the cardiac cycle of relaxation and...Ch. 8 - Describe the function of the SA and AV nodes as...Ch. 8 - Prob. 8CR
Ch. 8 - Prob. 9CRCh. 8 - Prob. 10CRCh. 8 -
1. _______ carry blood away from the heart and...Ch. 8 - Prob. 2TYCh. 8 - Which of the choices represents the order of...Ch. 8 - Prob. 4TYCh. 8 - Prob. 5TYCh. 8 - Prob. 6TYCh. 8 - Prob. 7TYCh. 8 - A pacemaker is used to correct: a. coronary artery...Ch. 8 - Prob. 9TYCh. 8 - Prob. 10TYCh. 8 - Prob. 11TYCh. 8 - Prob. 12TYCh. 8 - Prob. 13TYCh. 8 - Prob. 14TYCh. 8 - Prob. 15TYCh. 8 - Prob. 1AWKCh. 8 - When a coronary artery bypass graft (CABG) is...Ch. 8 - Soldiers have to stand in formation at full...Ch. 8 - Prob. 4AWKCh. 8 - Prob. 5AWKCh. 8 - Ventricular fibrillation is a potentially fatal...Ch. 8 - Prob. 7AWKCh. 8 - Last night, you and your roommate were sound...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- Below are drawings of three different action potentials. Two of these occur in the heart, and one occurs in skeletal muscle. Which one comes from a contractile cardiac muscle cell? A skeletal muscle cell? A cardiac pacemaker cell? For each one, state which ion is responsible for the depolarization phase and which ion is responsible for the repolarization phase.arrow_forwardThe ventricular walls of the human heart are more muscular as compared to the atrial walls. Why do cardiac muscles have a slow onset of contraction and prolonged contraction?arrow_forwardRoberto is a 78-year-old male who has recently been diagnosed with Class III Congestive Heart Failure (CHF). His physician told him that his left ventricle has become stiff and cannot relax. Although there is no current treatment that can “fix” Roberto’s condition, he is prescribed two medications: an ACE inhibitor and beta blockers.Briefly describe how beta-blockers will influence Roberto’s heart function, specifically the physiology of the ventricles.arrow_forward
- What 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_forwardRoberto is a 78-year-old male who has recently been diagnosed with Class III Congestive Heart Failure (CHF). His physician told him that his left ventricle has become stiff and cannot relax. Although there is no current treatment that can “fix” Roberto’s condition, he is prescribed two medications: an ACE inhibitor and beta blockers. Briefly describe how beta-blockers will influence Roberto’s heart function, specifically the physiology of the ventricles.arrow_forwardIn a sheet of ventricular cardiac muscle tissue, we should be able to observe electricity spreading between adjacent muscle cells (TRUE or FALSE) and from Purkinje fibers to muscle cells (TRUE or FALSE) via electrical synapses that form between the cell membranes.arrow_forward
- High pressure in the systemic and pulmonary circuit often results in ventricular hypertrophy in which the ventricle enlarges to pump against the greater force. Which side(s) of the heart would affected by high pressure in the pulmonary circuit? Which side(s) of the heart would be affected by high pressure in the systemic circuit? Could you explain this answer? Thank youarrow_forwardWhich of the following channels is responsible for generating the long plateau found in the action potentials of ventricular myocytes? a-slow Na+ channels b-slow Ca2+ channels c-leaky Ca2+ channels d-leaky Na+ channelsarrow_forwardWhy do the cardiac muscles cells demonstrate autorhythmicity?arrow_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_forwardWhat action potential of specialized heart cells know the function of each channel and the process?arrow_forwardThe rapid depolarization phase of heart pacemaker cells is caused by which of the following? movement of Na+ through funny channels movement of Ca++ through L-type channels movement of Na+ and Ca++ through funny channels movement of K+ through funny channels all of the abovearrow_forward
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