1.Consider a normal individual who quickly goes from a supine posture to an erec

Question

1.Consider a normal individual who quickly goes from a supine posture to an erect one. Predict the changes (increase/decrease/no change) that will occur in the following cardiovascular parameters. Choose 2 (two) and give a complete reason for your answer. Citations are not required, but may be instrumental for making your case with your answer. (4 points, 2 point for each. Be complete in your explanation)

a.     Stroke Volume (increase/decrease/no change) - Why?

        b. Heart Rate (increase/decrease/no change) - Why?

        c. Cardiac Output (increase/decrease/no change) - Why?

        d. Total Peripheral Resistance (increase/decrease/no change) - Why?

        e. Pressure at the root (beginning) of the aorta (increase/decrease/no change) - Why?

        f. Arterial pressure in foot (increase/decrease/no change) - Why?

        g. Capillary pressure in foot (increase/decrease/no change) - Why?

        h. Arterial pressure in cerebral blood vessels (increase/decrease/no change) - Why?

Explanation / Answer

Changing posture from supine to erect position causes poolup of blood in the lower half of the bofy, this reduces the throracic return and cardiac output and hence reduced arterial pressure. Baroreceptors sense the fall in BP and activate a sympathetic response. This causes increased peripheral resistance, and increased heart rate. .

A. Stroke Volume ----------------------> Decrease

  b. Heart Rate -------------------------------> Increase

   c. Cardiac Output ------------------------------> Decrease

        d. Total Peripheral Resistance --------------> Increase

        e. Pressure at the root (beginning) of the aorta -----------------> Decrease

        f. Arterial pressure in foot ---------------------------------------------> Increase (Due to pool up of blood)

        g. Capillary pressure in foot --------------------------------------------> Increase

        h. Arterial pressure in cerebral blood vessels -----------------------> Decrease (Due to decreased systemic blood pressure).

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