Could you try to explain as much as possible? Thank you so much! As the posture

Question

Could you try to explain as much as possible? Thank you so much!

As the posture of the body changes - for example, in going from lying down to standing up - the effects of gravity on cardiovascular function change significantly. Nevertheless, mean arterial pressure is maintained more or less constantly. In this problem, we consider the phenomenon and the mechanisms that generate it Consider a normal individual who quickly goes from a supine (lying down) posture to an erect one. Predict the changes (increase/decrease/no change) that will occur in the following cardiovascular parameters. stroke volume heart rate cardiac output total peripheral resistance arterial pressure in foot venous pressure in foot arterial pressure in cerebral blood vessels

Explanation / Answer

When the body posture changes from supine (lying) to erect, then

A. stroke volume : decreases

B. heart rate : increases.

C. Cardiac output: increases

D. total peripheral resistance : decreases

E. arterial pressure in foot : decreases

F. Venous pressure in foot: increases

G. Arterial pressure in cerebral blood vessels : decreases.

When the body posture changes from supine to erect, the gravitational force acts on the blood flow of lower extremities resulting in increased ventricular pressure. This shift causes to decrease the stroke volume, arterial pressure and arterial pressure in cerebral blood vessels. The heart rate in increased due to Frank-Starling mechanism and results in increased cardiac output.

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