ANATOMY & PHYSIOLOGY
4th Edition
ISBN: 9781264719969
Author: McKinley
Publisher: MCG
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Textbook Question
Chapter 19, Problem 7DYKB
Why is it necessary to stimulate papillary muscles in the ventricle slightly earlier than the rest of the ventricular wall myocardium?
- a. to assure rapid conduction speed of the action potential
- b. to pull on AV valve cusps to prevent backflow
- c. to assure blood will surge toward the semilunar valves
- d. to assure coordinated contraction of the ventricular myocardium
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Why is it necessary to stimulate papillary muscles in the ventricle slightly earlier than the rest of the ventricular wall myocardium?
a. to assure rapid conduction speed of the action potential
b. to pull on AV valve cusps to prevent backflow
c. to assure blood will surge toward the semilunar valves
d. to assure coordinated contraction of the ventricular myocardium
Which of the following statements is true about the SA (sinoatrial) node?
a. The action potential created by the pacemaker cells of the SA node directly stimulates the contractile cells of both the atria and ventricles.
b. The rate of spontaneous depolarization of nodal cells is the fastest in the SA node.
c. Pacemaker cells in the SA node form a pathway between the SA and AV nodes.
d. The pacemaker cells, which establish the heart rate, are located only in the SA node.
Suppose that a pacemaker activity in the AV node overtakes the SA node rhythm.
A. What could be the implicatiosn for the atrial and ventricular contraction-relaxation?
B. Draw the ECG for this situation and explain the differences compared to a normal ECG (if any)
Chapter 19 Solutions
ANATOMY & PHYSIOLOGY
Ch. 19.1 - Prob. 1WDYLCh. 19.1 - Prob. 2WDYLCh. 19.1 - Prob. 3WDYLCh. 19.1 - Prob. 4WDYLCh. 19.1 - Prob. 5WDYLCh. 19.2 - What is the bony structure that protects both the...Ch. 19.2 - Prob. 7WDYLCh. 19.2 - Prob. 8WDYLCh. 19.3 - Prob. 9WDYLCh. 19.3 - Prob. 10WDYL
Ch. 19.3 - Prob. 11WDYLCh. 19.3 - Prob. 12WDYLCh. 19.3 - Prob. 13WDYLCh. 19.3 - Prob. 14WDYLCh. 19.3 - Prob. 15WDYLCh. 19.3 - Prob. 16WDYLCh. 19.3 - What areas of the heart are deprived of blood when...Ch. 19.3 - Prob. 18WDYLCh. 19.4 - Prob. 19WDYLCh. 19.5 - Prob. 20WDYLCh. 19.5 - Which autonomic division is associated with the...Ch. 19.6 - Prob. 22WDYLCh. 19.6 - What is autorhythmicity? Describe how nodal cells...Ch. 19.6 - What is the path of an action potential through...Ch. 19.6 - What anatomic features slow the conduction rate of...Ch. 19.7 - In which direction does Ca2+ move in response to...Ch. 19.7 - What three electrical events occur at the...Ch. 19.7 - What is the significance of the extended...Ch. 19.7 - What events in the heart are indicated by each of...Ch. 19.8 - Pressure changes that occur during the cardiac...Ch. 19.8 - What is occurring during ventricular ejection?Ch. 19.8 - Prob. 32WDYLCh. 19.8 - Define end-diastolic volume, end-systolic volume,...Ch. 19.9 - What are the two factors that determine cardiac...Ch. 19.9 - What is the cardiac output at rest and during...Ch. 19.9 - Prob. 36WDYLCh. 19.9 - Describe the atrial reflex, which involves...Ch. 19.9 - Prob. 38WDYLCh. 19.9 - Prob. 39WDYLCh. 19.10 - What would be the path of blood flow through the...Ch. 19 - Which of the following is the correct circulatory...Ch. 19 - The pericardial cavity is located between the a....Ch. 19 - How is blood prevented from backflowing from the...Ch. 19 - ____ 4. Venous blood draining from the heart wall...Ch. 19 - _____ 5. Calcium channels in the nodal cells...Ch. 19 - ____6. Action potentials are spread rapidly...Ch. 19 - Why is it necessary to stimulate papillary muscles...Ch. 19 - ____ 8. Preload is a measure of a. stretch of...Ch. 19 - ____ 9. All of the following occur when the...Ch. 19 - ____10. What occurs during the atrial reflex? a....Ch. 19 - Prob. 11DYKBCh. 19 - Compare the structure, location, and function of...Ch. 19 - Prob. 13DYKBCh. 19 - Explain why the walls of the atria are thinner...Ch. 19 - Describe the structure and function of...Ch. 19 - Explain the general location and function of...Ch. 19 - Describe the functional differences in the effects...Ch. 19 - Prob. 18DYKBCh. 19 - List the five events of the cardiac cycle, and...Ch. 19 - Define cardiac output, and explain how it is...Ch. 19 - A young man was doing some vigorous exercise when...Ch. 19 - A young man was doing some vigorous exercise when...Ch. 19 - Prob. 3CALCh. 19 - Prob. 4CALCh. 19 - During surgery, the right vagus nerve was...Ch. 19 - Prob. 1CSLCh. 19 - Prob. 2CSLCh. 19 - Your grandfather was told that his SA node...
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- PREDICT A patients mitral valve (left AV valve) does not close completely at the beginning of ventricular systole. What effect would this have on the cardiac cycle?arrow_forwardSA node is the main pacemaker of the heart. Why is the normal heart rate lower than the intrinsic firing rate of the SA node? A. sympathetic inputs from the hypothalamus are slowing it down B. parasympathetic inputs from medulla oblongata are slowing it down C. there is inertia in heart muscle as it takes time for impulse to spread through all the cells D. centrifugal inputs from the AV node are slowing it downarrow_forwardwhich of the following mechanisms contributes most to the deterioration of myocardial perfusion in patients with a progressively dilating left ventricle and a cycle of gradual decompensation. A. decreasing left ventricular radius B. decreasing peripheral vascular resistance C. decreasing vestibular pressure D. increasing left ventricular wall tension E. increasing left ventricular wall thicknessarrow_forward
- Using the ECG recording provided below, how do we know that this extrasystole event (i.e., indicated by the arrow) is occurring in the ventricles and not the atria? a. None of the options are correct b. Extrasystole event is smaller in amplitude than the QRS complex c.Event occurs after a T-wave d.Large ECG amplitude compared with the P-wave e.Event occurs after a P-wavearrow_forwardAll of the following occur when the ventricles contract except a. the AV valves close. b. blood is ejected into the aorta. c. the semilunar valves open. d. blood from the pulmonary trunk enters the atria.arrow_forwardWhich of the following is/are true concerning the opening and closing of the cardiac valves? A. valves operate according to the pressures on either side of the valve B. valve operation is constantly being controlled by the medulla oblongata C. valve operation is determined directly by the cardiac action potential (electrical currents control the opening and closing of the valves.) D. valve operation is directly controlled by the papillary muscles within the ventricular wall. E. None of the above is correct.arrow_forward
- The following is correct about valvular structures A. The AV valves are the structures that divide the upper atria from the lower ventricles B. The pulmonic vale separates the left ventricle from the system circulation C. The tricuspid valve separates the left atrium from the left ventricle D. The mitral valve separates the right atrium from the right ventricle Choose the correct answerarrow_forwardWithin the T-P interval of the EKG... a. The 2nd heart sound is heard b. the semilunar valves are open c. Ventricular pressure is higher than atrial pressure d. Ventricular cardiomyocytes are relaxed e. L-type calcium current is dominant in the ventricular cardiomyocytesarrow_forwardWhich cell types are associated with spontaneous action potential generation in the absence of an external stimulus from other tissues. A. Sino-Atrial node cells (SA node). B. Atrial cells C. Ventricular cells. D. Endothelial cells. E. A and D.arrow_forward
- What event(s) occur during the QRS complex of an electrocardiogram? Select one: a. Repolarization of the ventricles b. Depolarization of the atria and repolarization of the ventricles c. Depolarization of the ventricles and repolarization of the atria d. Depolarization of the atriaarrow_forwardWhat 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_forwardWhich heart valve(s) is/are open during the Ejection phase of the cardiac cycle? A. Tricuspid B. Aortic semilunar valve C. Bicuspid D. Both B & Carrow_forward
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