Definition

Noun: * Alpha-adrenoceptor: A type of receptor found on the membranes of certain cells, primarily those of the sympathetic nervous system. These receptors specifically bind to and are activated by the neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline). Their activation mediates specific physiological responses, such as the constriction of blood vessels (vasoconstriction).

Usage

• Alpha-adrenoceptor is a specialized term used in physiology, pharmacology, and medicine.
• It is often discussed in contrast to beta-adrenoceptors, as both types respond to the same neurotransmitters but produce different effects in the body.
• The term is typically used in scientific writing, research papers, and clinical contexts.

Examples

• The drug works by selectively blocking the alpha-adrenoceptor, which leads to a drop in blood pressure.
• Researchers are studying the distribution of alpha-adrenoceptor subtypes in different tissues.
• Stimulation of the vascular alpha-adrenoceptor causes vasoconstriction.

Advanced Usage

• Alpha-adrenoceptor subtypes: The term is often specified further into alpha-1 and alpha-2 adrenoceptor subtypes, which have distinct locations and functions.
  • Alpha-1 adrenoceptors are primarily located on vascular smooth muscle; their activation causes contraction.
  • Alpha-2 adrenoceptors are often found on nerve terminals; their activation typically inhibits further neurotransmitter release.
• Alpha-adrenoceptor agonist/antagonist: These are common compound terms in pharmacology.
  • An alpha-adrenoceptor agonist is a drug that stimulates these receptors (e.g., phenylephrine).
  • An alpha-adrenoceptor antagonist (or alpha-blocker) is a drug that blocks these receptors (e.g., prazosin).

Variants and Related Words

• Alpha receptor: A common informal synonym for alpha-adrenoceptor.
• Adrenergic receptor: The broader category of receptors that includes both alpha- and beta-adrenoceptors.
• Adrenoceptor: The general term for receptors that respond to adrenaline (epinephrine) and noradrenaline (norepinephrine).

Synonyms

• Alpha receptor
• α-adrenergic receptor
• Alpha adrenergic receptor

Related Phrases and Concepts

• Sympathetic nervous system: The part of the autonomic nervous system where alpha-adrenoceptors are heavily involved.
• Vasoconstriction: A primary physiological effect mediated by alpha-1 adrenoceptors.
• Noradrenergic: Pertaining to or denoting neurons that use norepinephrine and the receptors (like alpha-adrenoceptors) they act upon.

Noun

1. 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)