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Endothelins released by the endothelium act on the vessel wall in which way?
AThey relax smooth muscle and lower blood pressure
BThey thicken the basement membrane over time
CThey dissolve elastic fibers in the tunica media
DThey constrict smooth muscle and raise blood pressure
Answer & Solution
Correct answer: D. They constrict smooth muscle and raise blood pressure
1. The endothelium is not a passive boundary; it releases local chemical signals.
2. Endothelins are one such signal, and they constrict the smooth muscle of the vessel wall.
3. A narrower lumen means higher blood pressure, so endothelins push pressure up.
4. Sustained overproduction of endothelins is linked to hypertension and cardiovascular disease.
5. Nitric oxide, not endothelin, is the endothelial signal that relaxes smooth muscle.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 20 "The Cardiovascular System: Blood Vessels and Circulation", section 20.1 Structure and Function of Blood Vessels_
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