Question

What part of this equation do veins affect? (MAP = SV x HR x TPR)

Answer 1

MAP = SV x HR x TPR

MEAN ARTERIAL PRESSURE = STROKE VOLUME * HEART RATE * TOTAL PERIPHERAL RESISTANCE

STROKE VOLUME IS AFFECTED BY VEINS

• . The cardiac output (CO) is the amount of blood ejected from the left ventricle, and normally it is equal to the venous return
• CO also equals the rate of oxygen consumption divided by the difference in arterial and venous oxygen content

. The stroke volume is the amount of blood pumped out of the heart after one contraction. It is the difference in end-diastolic (EDV) and end-systolic volume (ESV).

It increases with increased contractility, increased preload, and decreased afterload. Also, contractility of the left ventricle increases with catecholamines by increasing intracellular calcium ions and lowering extracellular sodium.

The preload is the pressure on the ventricular muscle by the ventricular EDV.

Systemic veins have a lower decrease in pressure because it has low resistance. The venous system is very compliant contains up to 70% of the circulating blood at once. A small change in venous pressure can mobilize the blood stored in the venous system