| a site on a cell that, upon interaction with epinephrine or norepinephrine, controls vasoconstriction, intestinal relaxation, pupil dilation, and other physiological processes. |
alpha-adrenergic receptor n.
Any of various cell membrane receptors that can bind with norepinephrine and related substances that activate or block the actions of the cells containing such receptors; these cells initiate physiological responses such as vasoconstriction, pupil dilation, and contraction of pilomotor muscles. Also called alpha-receptor.