kris2c
Forum Senior
Topics: 30
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During normal diastole, which of the following is most important in preventing over-distension of the ventricles?
A. Adjacent lungs
B. Aortic valve
C. Diaphragm
D. Fibrous pericardium
E. Mitral valve
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Kris2c
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D. Fibrous pericardium
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Aortic valve
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| auubar
Forum Senior
Topics: 30
Posts: 182
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I will choose fibrous pericardium
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| kris2c
Forum Senior
Topics: 30
Posts: 108
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The correct answer is D.
The fibrous pericardium, which surrounds the heart, does not simply separate the heart from other chest structures, but has the important physiologic role of limiting the distension of the heart during diastole.
This helps keep the (normal) heart functioning in a useful part of Starling's curve.
In congestive heart failure, the slow enlargement of the heart also enlarges the fibrous pericardium, and this protective function may be lost.
The lungs (choice A) and diaphragm (choice C) do not usually significantly limit cardiac expansion during diastole.
Shutting and opening of the aortic (choice B) and mitral valves (choice E) are mechanical events that occur secondary to the changes in muscle tone in the cardiac chambers.
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Kris2c
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