Question

Consider how all the factors contributing to MAP impact each other, and put the following parameters in order regarding cause and effect, starting with a reduction in blood volume (due to donating blood, for example), and moving through the compensatory mechanisms involved.

1. MAP is restored towards its set point

2. Heart rate, ventricular contractility, venous return, and TPR all increase

3. The sympathetic activity increases and parasympathetic activity decreases

4. Baroreceptor activity decreases

5. MAP decreases

6. Cardiac output decreases

7. Blood volume is reduced

8. Venous return decreases

9. EDV decreases

10. Stroke volume decreases

put in order

Answer 1

1. blood volume is reduced (due to blood donation)
2. venous return decreases ( when the blood volume is less, venous return to the heart decreases)
3. EDV decreases (EDV is proportional to venous return)
4. stroke volume decreases (stroke volume is the amount of blood pumped from each ventricle in a heartbeat. it is dependent on the blood in the ventricle before its contraction, means its dependent on EDV)
5. cardiac output decreases (when stroke volume decreases, cardiac output decreases as cardiac output is the product of stroke volume and heart rate)
6. MAP decreases (MAP reduces when cardiac output decreases)
7. baroreceptor activity decreases (when MAP is reduced, the street on the baroreceptor is reduced activating the sympathetic system by the vasomotor center in the brain and cardio acceleratory center)
8. the sympathetic activity increases and the parasympathetic activity decreases
9. heart rate, ventricular contractility, venous return, and TPR all increases (increase in sympathetic activity increases heart rate, force of contarion, venous return by vasoconstriction and TPR also increase)
10. MAP is restored towards its set point.