Which blood vessels can dilate and constrict?
Started by AOT11
Get help with your application
Use all the free resources available to you from SDN: articles, guides, expert advising, forums discussions, and school research.
Arteries are lined with smooth muscle and are able to elicit a vasoconstricting compensatory effect in response to hypovolemia. Many arteries and larger junction possess receptors to endogenous catecholamines and other hormones that allow them to respond for fight and flight conditions ect.
Arterioles have sphincter muslces that precede the capillary itself. This serves to shunt blood away from certain regions of the circulatory system in order to prep the body for fight or flight as well.
Veins, however, mostly lack smooth muscle that permits autonomic vasoconstriction and dilation. The venous circulation actually serves as a reservoir for blood as the lack of smooth muscle permits some stretching. If you heard of an AAMC or other test mention constriction of veins, they were likely referring to how skeletal muscles that surround certain veins can apply a force to the vessel and effectively "constrict" them.
Arterioles have sphincter muslces that precede the capillary itself. This serves to shunt blood away from certain regions of the circulatory system in order to prep the body for fight or flight as well.
Veins, however, mostly lack smooth muscle that permits autonomic vasoconstriction and dilation. The venous circulation actually serves as a reservoir for blood as the lack of smooth muscle permits some stretching. If you heard of an AAMC or other test mention constriction of veins, they were likely referring to how skeletal muscles that surround certain veins can apply a force to the vessel and effectively "constrict" them.
Perpetually, what you say about veins simply is not true. Veins do have smooth muscle, just not as much as arteries. Septic Shock is a condition that causes all blood vessels in the body to dilate due to the abnormally high levels of nitric oxide in circulating blood caused by the infection. It is insane that practicing physicians do not know the power of the veins in controlling blood flow around the system. look more into the anatomy books about blood vessels. Thanks.
