Why are vasodilation and vasoconstriction the main mechanisms to change blood flow?
A)Blood vessel length is relatively fixed and has no effect on blood flow.
B)Blood hematocrit has no effect on blood flow.
C)Leakage of fluids from the capillaries has no effect on blood flow.
D)Sympathetic activation has no effect on blood flow.

Question

Quizplus · Accepted Answer

Blood vessel length is relatively fixed and cannot be easily changed, so vasodilation and vasoconstriction are the primary mechanisms by which blood flow can be altered. Hematocrit and capillary leakage may affect overall circulation, but they do not directly impact blood flow through specific vessels. Sympathetic activation can lead to vasoconstriction, which can affect blood flow, but this is still an example of vasomotor control.

Why Are Vasodilation and Vasoconstriction the Main Mechanisms to Change