BIOLOGY
12th Edition
ISBN: 9781260169614
Author: Raven
Publisher: RENT MCG
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Textbook Question
Chapter 48, Problem 1A
In vertebrate hearts, atria contract from the top, and ventricles contract from the bottom. How is this accomplished?
a. Depolarization from the SA node proceeds across the atria from the top; depolarization from the AV node is carried to the bottom of the ventricles before it emanates over ventricular tissue.
b. The depolarization from the SA node is initiated from motor neurons coming down from our brain; depolarization from the AV node is initiated from motor neurons coming up from our spinal cord.
c. Gravity carries the depolarization from the SA node down from the top of the heart; contraction of the diaphragm forces depolarization from the AV node from the bottom up.
d. This statement is false; both contract from the bottom.
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Students have asked these similar questions
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
SA 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 down
What is the correct order of events in the left ventricle during the systole phase of the cardiac cycle?
a.
Ventricular repolarization, ventricular relaxation, 2nd heart sound, AV valve opens, blood moves in
b.
QRS-complex, ventricular contraction, 2nd heart sound, aortic valve opens, blood moves out
c.
P-wave, increased ventricular pressure, 1st heart sound, aortic valve opens, blood moves in
d.
QRS complex, ventricular contraction, 1st heart sound, AV valve opens, blood moves out
e.
QRS complex, increased ventricular pressure, AV-valve closes, blood moves out
Chapter 48 Solutions
BIOLOGY
Ch. 48.1 - Prob. 1LOCh. 48.1 - Prob. 2LOCh. 48.2 - Prob. 1LOCh. 48.2 - Prob. 2LOCh. 48.2 - Prob. 3LOCh. 48.3 - Prob. 1LOCh. 48.3 - Prob. 2LOCh. 48.4 - Prob. 1LOCh. 48.4 - Prob. 2LOCh. 48.5 - Prob. 1LO
Ch. 48.5 - Prob. 2LOCh. 48.5 - Prob. 3LOCh. 48.5 - Prob. 4LOCh. 48 - Prob. 1DACh. 48 - Prob. 1IQCh. 48 - Prob. 2IQCh. 48 - An ECG measures a. changes in electrical potential...Ch. 48 - Systole is vitally important to heart function and...Ch. 48 - Which of the following is the correct sequence of...Ch. 48 - Which of the following statements is not true? a....Ch. 48 - Prob. 5UCh. 48 - Prob. 6UCh. 48 - When a sphygmomanometer is used, a. blood pulses...Ch. 48 - Prob. 8UCh. 48 - In vertebrate hearts, atria contract from the top,...Ch. 48 - Prob. 2ACh. 48 - The difference between the amphibian and mammal...Ch. 48 - Prob. 4ACh. 48 - Humans have a number of mechanisms that help to...Ch. 48 - Prob. 2SCh. 48 - Is the evolution of the four-chambered heart...Ch. 48 - Prob. 4S
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- Which of the following statement/s is/are not true about regulation of heart rate? A. The brainstem contains the cardiac centers which are the accelerator center and the inhibitory center. (medulla) B. Sympathetic impulses to the heart increase rate and force of contraction. C. Parasympathetic impulses from cranial nerve X to the heart causes reduction in the heart rate. D. The cranial nerve IX is motor for the carotid receptors. (sensory)arrow_forwardWhat two values are needed in order to calculate cardiac output (CO) for a ventricle? a. end-diastolic volume (EDV) and end-systolic volume (ESV) b. stroke volume (SV) and blood pressure (BP) c. stroke volume (SV) and heart rate (HR) d. heart rate (HR) and end-diastolic volume (EDarrow_forwardWhat will happen to the next level of exercise tolerance in a person whose heart is being paced by the AV node? A. Level of exercise tolerance will stay the same B. Level of exercise tolerance will decrease C. Level of exercise tolerance will increasearrow_forward
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