Final answer:
TPR increases with vasoconstriction and decreases with vasodilation. Changes in vessel diameter affect blood flow and resistance, and the body may compensate for increased resistance with higher blood pressure, which has potential risks.
Step-by-step explanation:
The question pertains to how changes in blood vessel diameter affect total peripheral resistance (TPR). TPR increases when the vessels are vasoconstricted, and TPR decreases when the vessels are vasodilated. Vasoconstriction refers to the narrowing of the blood vessels, which increases resistance and pressure but decreases blood flow.
Conversely, when blood vessels vasodilate, they widen, reducing resistance and allowing more blood to flow through.
Changes to blood vessel diameter and TPR occur in response to various physiological and pathological conditions. For example, when there is a decrease in the vessel radius due to plaque buildup, TPR can increase significantly, inhibiting blood flow.
The body may attempt to compensate by raising blood pressure to maintain blood flow despite increased TPR. However, this can present health risks.
Throughout the day, the diameter of blood vessels can change frequently due to signals that induce vasodilation and vasoconstriction. This is part of the body's mechanism for regulating blood pressure and ensuring that different tissues receive appropriate amounts of blood based on their needs at any given moment.