The Frank-Starling law of the heart can be demonstrated when an individual takes a deep breath. This is because:
A. the heart expands during inhalation.
B. the negative intrathoracic pressure induces a larger than normal venous return to the right atrium, thereby stretching the wall of the right ventricle.
C. sympathetic impulses are sent to the heart during inspiration.
D. both a and c occur.
Answer: B. the negative intrathoracic pressure induces a larger than normal venous return to the right atrium, thereby stretching the wall of the right ventricle.
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