Human Physiology
15th Edition
ISBN: 9781259864629
Author: Fox, Stuart Ira
Publisher: Mcgraw-hill Education,
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Textbook Question
Chapter 13, Problem 19RA
What characteristic of the SA node distinguishes it from other possible pacemaker regions and allows it to function as the normal pacemaker? How do action potentials from the SA node reach the atria and the ventricles?
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What causes the pacemaker cells of the SA node to trigger an action potential?
The left AV valve has only two large leaflets, while the right AV valve has three smaller leaflets. It is a general principle of physiology that structure is a determinant of—and has coevolved with—function. Although it is unknown why the two valves differ in structure in this way, what difference in the functional demands of the left side of the heart might explain why there is one less valve leaflet than on the right side?
What anatomic features slow the conduction rate of the action potential as it passes through the AV node? What is the function of this delay?
Chapter 13 Solutions
Human Physiology
Ch. 13 - State the components of the circulatory system...Ch. 13 - Prob. 1bCPCh. 13 - Prob. 2CPCh. 13 - Prob. 3CPCh. 13 - Describe how the rate of erythropoiesis is...Ch. 13 - Prob. 5aCPCh. 13 - Prob. 5bCPCh. 13 - Using a flow diagram (arrows), describe the...Ch. 13 - Use a flow diagram to describe the systemic...Ch. 13 - List the AV valves and the valves of the pulmonary...
Ch. 13 - Discuss how defective valves affect blood flow...Ch. 13 - Prob. 7bCPCh. 13 - Prob. 8aCPCh. 13 - Prob. 8bCPCh. 13 - Draw a figure to illustrate the pressure...Ch. 13 - Prob. 10aCPCh. 13 - Using a line diagram, illustrate a myocardial...Ch. 13 - Draw an ECG and label the waves. Indicate the...Ch. 13 - Draw a figure that shows the relationship between...Ch. 13 - Prob. 11cCPCh. 13 - Prob. 12aCPCh. 13 - Prob. 12bCPCh. 13 - Explain the functions of capillaries and describe...Ch. 13 - Prob. 14CPCh. 13 - Prob. 15CPCh. 13 - Identify normal and pathological causes of...Ch. 13 - Prob. 16bCPCh. 13 - Prob. 17aCPCh. 13 - Explain how the lymphatic system and the...Ch. 13 - Prob. 18CPCh. 13 - Prob. 1RACh. 13 - All arteries in the body contain oxygen-rich blood...Ch. 13 - The "lub," or first heart sound, is produced by...Ch. 13 - The first heart sound is produced at
Ch. 13 - Changes in the cardiac rate primarily reflect...Ch. 13 - Prob. 6RACh. 13 - Prob. 7RACh. 13 - The cells that normally have the fastest rate of...Ch. 13 - Which of these statements is true? a. The heart...Ch. 13 - Prob. 10RACh. 13 - Prob. 11RACh. 13 - Prob. 12RACh. 13 - Prob. 13RACh. 13 - Prob. 14RACh. 13 - Prob. 15RACh. 13 - During the phase of isovolumetric relaxation of...Ch. 13 - Peristaltic waves of contraction move fluid within...Ch. 13 - Describe how the pacemaker cells produce a...Ch. 13 - What characteristic of the SA node distinguishes...Ch. 13 - Compare the duration of the heart's contraction...Ch. 13 - Step by step, describe the pressure changes that...Ch. 13 - Can a detective valve be detected by an ECG? Can a...Ch. 13 - Describe the causes of the P, QRS, and T waves of...Ch. 13 - The lungs are the only organs that receive the...Ch. 13 - Prob. 25RACh. 13 - Prob. 26RACh. 13 - Prob. 27RACh. 13 - Prob. 28RACh. 13 - Prob. 29RACh. 13 - Prob. 30RACh. 13 - Prob. 31RACh. 13 - Prob. 32RACh. 13 - Prob. 33RACh. 13 - Prob. 34RACh. 13 - Prob. 35RACh. 13 - Prob. 36RACh. 13 - Prob. 37RACh. 13 - Prob. 38RACh. 13 - Prob. 39RACh. 13 - Prob. 40RACh. 13 - Prob. 41RACh. 13 - Prob. 42RA
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- How does the depolarization of pacemaker cells differfrom the depolarization of other cardiac cells? What is thepacemaker potential?arrow_forwardWhat 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_forwardWhat is the most characteristic feature of a wandering pacemaker rhythm?arrow_forward
- Which part of the intrinsic conduction system directly excites ventricular myocardial cells? In which direction does the depolarization wave travel across the ventricles?arrow_forwardThe ST segment in the EKG is typically quiet and on the isoelectric line (like the T-P segment). What is happening during the ST segment in the EKG such that we see no waves? a) There is no electrical activity happening in the ventricles between the S and T waves b) The heart is relaxed and filling with blood c) The ST segment is representative of the plateau of the many ventricular action potentials happening at that point d) There is no longer Na+ influx during the ST segment so no waves are visible e) The ST segment is during ventricular repolarization and repolarization is not seen on the EKGarrow_forward
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