Which phases of the cardiac action potential coincide with the contraction phase of the cardiac myocyte response to the action potential? Question 34 options: Phase 0, phase 1, phase, 2, phase 3, phase 4 Phase 1, Phase 2 Phase 3, phase 4
Added by Curtis M.
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The cardiac action potential consists of several phases: - Phase 0: Rapid depolarization due to sodium influx. - Phase 1: Initial repolarization due to sodium channels closing and potassium efflux. - Phase 2: Plateau phase where calcium influx balances potassium Show more…
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Which of the following statements about the action potentials in contractile myocardial cells (cardiac muscle) is INCORRECT? Answers: 1. Compared to skeletal muscle cells, contractile myocardial cells have a lower (more negative) resting membrane potential. 2. While cells in the SA node are autorhythmic and are able to generate action potentials without any outside stimuli, contractile myocardial cells require an outside stimulus to generate an action potential. 3. The duration of an action potential in a contractile myocardial cell is greater than the duration of an action potential in a typical neuron. 4. During the repolarization phase of a contractile myocardial action potential, the cell is highly permeable to sodium, potassium, and calcium.
Rupsa S.
Q1) At the time of the QRS complex, a) The atria contract b) Ventricular pressure exceeds atrial pressure c) The ventricular wall repolarizes d) Aortic pressure initially increases e) Venous return is filling the ventricle Q2) A potential 5-fold increase in cardiac output in a person going from a resting state to one of intense exercise suggests that a) The diastolic phase of the cardiac cycle has increased b) The rate of Na+ channel inactivation per heartbeat in the ventricular myocytes has changed c) The systolic phase of the cardiac cycle has increased d) Both the stroke volume and pacing rate of the heart must have increased e) Resistance in the arteries has increased Q3) What would happen if the skeletal muscle voltage sensor failed to change from its activated state to its inactivated state following membrane depolarization? a) The Ca2+ release channel would not activate b) Released Ca2+ will not be enough to activate force production c) Ca2+ release from sarcoplasmic reticulum would be prolonged d) There would be no Ca2+ release e) The surface membrane would not repolarize Q4) Which of the following events occur during systole? a) Blood moves from the atria to the ventricle b) The pressure in the left ventricle exceeds that of the aorta c) There is depolarization of the atria d) There is a delay of the action potential at the atrioventricular (AV) node e) Ca2+ concentration is low in the cytoplasm of the ventricular myocytes
Adi S.
Refer to the following graph of a cardiac muscle cell action potential. During phase "0" of this graph, which ion(s) are moving across the cell membrane? Sodium Calcium Calcium and sodium Potassium Calcium and potassium
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