| a site on a cell that, upon interaction with epinephrine or norepinephrine, controls vasoconstriction, intestinal relaxation, pupil dilation, and other physiological processes. |

| al·pha-re·cep·tor (āl'fə-rĭ-sěp'tər) n. A site in the autonomic nervous system in which excitatory responses occur when adrenergic agents, such as norepinephrine and epinephrine, are released. Activation of alpha-receptors causes various physiological reactions, including the stimulation of associated muscles and the constriction of blood vessels. Also called alpha-adrenergic receptor. |
alpha-receptor n.
See alpha-adrenergic receptor.