Human Physiology: An Integrated Approach (7th Edition)
7th Edition
ISBN: 9780321981226
Author: Dee Unglaub Silverthorn
Publisher: PEARSON
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Textbook Question
Chapter 14, Problem 19CC
What happens to the action potential of a myocardial autorhythmic cell if tetrodotoxin, which blocks voltage-gated Na+ channels, is applied to the cell?
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Chapter 14 Solutions
Human Physiology: An Integrated Approach (7th Edition)
Ch. 14 - A cardiovascular system has what three major...Ch. 14 - What is the difference between (a) the pulmonary...Ch. 14 - Which is more important for determining flow...Ch. 14 - The two identical tubes below have the pressures...Ch. 14 - All four tubes below have the same driving...Ch. 14 - Two canals in Amsterdam are identical in size, but...Ch. 14 - What prevents electrical signals from passing...Ch. 14 - Prob. 8CCCh. 14 - Prob. 9CCCh. 14 - Compare the receptors and channels involved in...
Ch. 14 - If a myocardial contractile cell is placed in...Ch. 14 - A drug that blocks all Ca2+ channels in the...Ch. 14 - Which ions moving in what directions cause the...Ch. 14 - At the molecular level, what is happening during...Ch. 14 - Lidocaine is a molecule that blocks the action of...Ch. 14 - What does increasing K+ permeability do to the...Ch. 14 - A new cardiac drug called ivabradine selectively...Ch. 14 - Do you think that the Ca2+ channels in...Ch. 14 - What happens to the action potential of a...Ch. 14 - In an experiment, the vagus nerve, which carries...Ch. 14 - Name two functions of the AV node. What is the...Ch. 14 - Prob. 22CCCh. 14 - Occasionally an ectopic pacemaker {ktopos, out of...Ch. 14 - Prob. 24CCCh. 14 - Which chamberatrium or ventriclehas higher...Ch. 14 - Prob. 26CCCh. 14 - Prob. 27CCCh. 14 - Prob. 28CCCh. 14 - Prob. 29CCCh. 14 - Why does ventricular pressure shoot up suddenly at...Ch. 14 - Prob. 31CCCh. 14 - Prob. 32CCCh. 14 - 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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- Why is it necessary for cells of the cardiac atria and ventricles to contract in a coordinated manner? How is this accomplished?arrow_forwardWhy is the cardiac action potential propagated more slowly in an AV node cell then in an atrial or ventricular myocyte? How can be AV conduction affected by hypokalemia? Briefly explain the mechanism by which the most popular beta-blocker metoprolol would affect cardiac muscle contractility and blood flow. How it affects heart rate and conduction?arrow_forwardWhy does the low calcium level produced by hypoparathyroidism decrease myocardial contractility?arrow_forward
- List an additional property of the myocardial contractile fibers and autorhythmic cells?arrow_forwardWhat major movements of ions account for each phase of the action potential of a typical myocardial cell?arrow_forwardIn the calculation of the heart rate using the number 300 method in the ECG, where did the number 300 come from? Why exactly was this method adopted?arrow_forward
- What are the difference between contractile cells of the heart and electrical cells responsible for generation and conduction of impulses. Why is the cardiac action potential propagated more slowly in an AV node cell than in an atrial or ventricular myocyte? How are the channels and ions that are responsible for depolarization and repolarization work? How can be AV conduction affected by hypokalemia?arrow_forwardIf all plasma membrane Ca21 channels in contractile cardiac muscle cells were blocked with a drug, what would happen to the muscle’s action potentials and contraction?arrow_forwardThe effective-refractory period present during Phase 2 of the actionpotential of ventricular myocytes:A)is relatively long because the Na+ current does not inactivate. B) is relatively long because K+ current is immediately activated once membrane potential becomes positive. C) prevents tetanus in the heart. D) is about twice as long as in skeletal musclearrow_forward
- The exact cause of blood clotting in the left atrium of the heart during atrial fibrillation (AF) is not known. In part it might be due to blood stasis (not moving) or it may result in combination with endothelial cells damage. (A) What are the potential mechanisms that might drive clotting and what markers might you look for in the blood to predict potential risk? (B) Other than treating the arrhythmia, what other pharmacological intervention might be provided to AF sufferers?arrow_forwardIn a cardiac contractile cell what is the mechanism involved in the change in membrane potential? Depolarization: P wave Repolarization: QRS Complex, Hyperpolarization: T wave Pacemaker: K+ and Na+ flow, Depolarization: Pca rises Repolarization: Pk rises Depolarization: Pna increases, Peak: Na channels close, Plateau: Calcium channels close & Potassium channels open, Repolarization Potassium flows out & Calcium flows in Pacemaker: K+ and Na+ flow, Depolarization: Pca rises Repolarization: Pk rises, 4. If channels close Depolarization: Pna increases, Peak: Na channels close, Plateau: Calcium channels open & Potassium channels close, Repolarization Potassium flows out & Calcium flows outarrow_forward1) Diagram and explain the mechanisms of a pacemaker potential for a nodal cell 2) Diagram and explain the mechanisms of a ventricular myocardial cell action potential.arrow_forward
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