kris2c
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A 65-year-old male visits his family practitioner for a yearly examination. Measurement of his blood pressure reveals a systolic pressure of 190 mm Hg and a diastolic pressure of 100 mm Hg. His heart rate is 74/min and pulse pressure is 90 mm Hg. A decrease in which of the following is the most likely explanation for the high pulse pressure?
A. Arterial compliance
B. Cardiac output
C. Myocardial contractility
D. Stroke volume
E. Total peripheral resistance
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Kris2c
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| peekay
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d- stroke volume
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| kris2c
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The correct answer is A.
A decrease in arterial compliance indicates that the arterial wall is stiffer (i.e., less distensible). When the compliance of the arterial system decreases, the rise in arterial pressure becomes greater for a given stroke volume pumped into the arteries. In the normal young adult, the systolic blood pressure is about 120 mm Hg and the diastolic blood pressure is about 80 mm Hg. Because the pulse pressure is the difference between the systolic and diastolic blood pressures, the normal pulse pressure is about 40 mm Hg in a healthy young adult. However, in older adults the pulse pressure sometimes increases as much as two times normal because the arteries become hardened by arteriosclerosis.
The cardiac output (choice B) itself has no direct effect on the pulse pressure; however, if a decrease in cardiac output is associated with a decrease in stroke volume, the pulse pressure would be expected to decrease.
A decrease in myocardial contractility (choice C) would be expected to decrease stroke volume, and therefore cause the pulse pressure to decrease.
A decrease in stroke volume (choice D) causes the pulse pressure to decrease because a smaller amount of blood enters the arterial system with each heartbeat, and the rise and fall of pressure during systole and diastole is decreased.
A decrease in total peripheral resistance (choice E), i.e., vasodilation, does not have a significant effect on the pulse pressure of the major arteries under normal conditions.
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Kris2c
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| peekay
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thank you for explanation
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