Alpha-adrenergic Receptor (Noun)
Meaning
Receptors postulated to exist on nerve cell membranes of the sympathetic nervous system in order to explain the specificity of certain agents that affect only some sympathetic activities (such as vasoconstriction and relaxation of intestinal muscles and contraction of smooth muscles).
Classification
Nouns denoting body parts.
Examples
- The subtypes of the alpha-adrenergic receptor have distinct properties in terms of the specific G proteins to which they are coupled.
- Phentolamine is a non-selective alpha-adrenergic receptor antagonist, which means that it blocks the action of these receptors across the entire body.
- It is a selective alpha 2 adrenergic receptor agonist, so it promotes all the effects mediated by alpha 2 receptors.
- Alpha-adrenergic receptors are stimulated on contraction of the radial smooth muscles in the radial follicles in the iris, putting a dilated pupil and allowing more light to enthrall the retina during dim light.
- Alpha-adrenergic receptors also constrict the blood vessels in their vicinity such as arteries or arterioles, causing a paradoxical effect on blood pressure near the heart.