Guided course 6:36Comparing Action Potentials in Pacemaker and Contractile CellsBruce Bryan640views17rank
08:34Ventricular Action Potential | Cardiac Action Potential | Part 1 | Phases | Cardiac PhysiologyByte Size Med452views
07:17Sinoatrial Node Potential | Pacemaker Potential | Cardiac Action Potential 2 | Cardiac PhysiologyByte Size Med499views
09:12Cardiac Myocyte Action Potential Phases Made Easy [Heart Muscle vs Pacemaker Physiology Animation]EZmed616views
Multiple ChoiceWhich of the following correctly identifies a difference between action potentials in cardiac and skeletal muscle?259views6rank
Multiple ChoiceCalcium ion channels open in response to changes in membrane potential. What type of opening mechanism do calcium ion channels in cardiac muscle exhibit?226views4rank
Multiple ChoiceAutorhythmicity is a unique feature of cardiac pacemaker cells. What feature of cardiac pacemaker cells allows them to be autorhythmic while other cardiac cells are not?244views7rank
Multiple ChoiceCardiac contractile tissue uses sodium, calcium, and potassium channels for depolarization and repolarization. During which phase of the action potential is the calcium channel open?246views1rank
Multiple ChoiceHow would you expect the absolute refractory period of a contractile cell to change if more potassium channels opened sooner after polarization?176views
Multiple ChoiceThe movement of ions in opposite directions at the same time is responsible for which of the following?198views3rank
Multiple ChoiceWhich statement below correctly describes how the channels that are active during the pacemaker potential are different from other ion channels used in action potentials?193views2rank
Textbook QuestionMultiple Choice More than one choice may apply. Which of the following depolarizes next after the AV node? a. b. c. d. e.197views1rank
Textbook QuestionThe cardiac skeleton of the heart has which two of the following functions? (a) It physically isolates the muscle fibers of the atria from those of the ventricles. (b) It maintains the normal shape of the heart. (c) It helps distribute the forces of cardiac contraction. (d) It allows more rapid contraction of the ventricles. (e) It strengthens and helps prevent overexpansion of the heart.152views
Textbook QuestionIn the heart, which of the following apply? (1) Action potentials are conducted from cell to cell across the myocardium via gap junctions, (2) the SA node sets the pace for the heart as a whole, (3) spontaneous depolarization of cardiac cells can occur in the absence of nerve stimulation, (4) cardiac muscle can continue to contract for long periods in the absence of oxygen. a. all of the above, b. 1, 3, 4, c. 1, 2, 3, d. 2, 3.384views
Textbook QuestionWhat is the cardiac cycle? What phases and events are necessary to complete a cardiac cycle?170views
Textbook QuestionWhich of the following is longer? (a) the refractory period of a cardiac contractile cell, (b) the refractory period of skeletal muscle fiber.147views
Textbook QuestionDescribe the function of the SA node in the cardiac cycle. How does this function differ from that of the AV node?131views
Textbook QuestionDescribe the effects of epinephrine, norepinephrine, glucagon, and thyroid hormones on the contractility of the heart.179views
Textbook QuestionMark the following statements as true or false. If a statement is false, correct it to make a true statement.a. The rapid depolarization phase of the contractile cell action potential is due to the opening of voltage-gated potassium ion channels.139views
Textbook QuestionMark the following statements as true or false. If a statement is false, correct it to make a true statement.b. Pacemaker cells lack a distinct plateau phase.133views
Textbook QuestionMark the following statements as true or false. If a statement is false, correct it to make a true statement.c. The plateau phase in contractile cells is due to the influx of calcium ions through calcium ion channels.153views
Textbook QuestionMark the following statements as true or false. If a statement is false, correct it to make a true statement.d.The repolarization phase of the contractile cell is due to the potassium ions rushing into the cell through potassium ion channels.172views
Textbook QuestionMark the following statements as true or false. If a statement is false, correct it to make a true statement.e. Open sodium ion channels cause hyperpolarization in pacemaker cells, which triggers HCN channels to open and begins a new action potential.151views
Textbook QuestionWhat are the effects of the plateau phase of the contractile cell action potential?156views
Textbook QuestionAn experimental toxin makes the refractory period of cardiac muscle cells equal in length to that of skeletal muscle fibers. Predict the consequences of this toxin. (Connects to Chapter 10)180views
Multiple ChoiceThe absolute refractory period refers to the time during which __________.1417views1rank
Multiple ChoiceThe noncontractile cardiac muscle cells that initiate their own depolarization and cause depolarization of the rest of the heart are called __________.1074views2rank
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