Which term also means automatic regulation or reflex control of blood flow in an area depending on the local needs?

• A. Homeostasis
• B. Vasomotor reflex
• C. Autonomic reflex
• D. Autoregulation

Answer: (C)

Local blood flow is kept appropriate by automatic, tissue-level adjustments in vessel diameter in response to the tissue’s own needs. This is called autoregulation. It’s an intrinsic mechanism, meaning the tissues themselves sense metabolic demand—such as low oxygen, high carbon dioxide, low pH, or buildup of metabolic byproducts—and adjust arteriolar resistance to keep flow fairly constant as perfusion pressure changes. Mechanisms include the myogenic response, where vessels constrict or dilate based on stretch, and metabolic controls, where vasodilators accumulate when metabolism is high (so blood flow increases to meet demand).

What this term captures best is the idea of automatic, local regulation of perfusion to match tissue needs, rather than a reflex mediated by the brain or autonomic nerves. In contrast, autonomic reflexes describe broader reflex pathways that regulate organs via the autonomic nervous system, and vasomotor reflexes are specific autonomic responses that change vessel diameter in a reflexive manner, not necessarily tied to local metabolic demand. Homeostasis is the overall maintenance of internal stability, not exclusive to local tissue perfusion.