Receptor (redirected from Nicotinic receptor)

receptor /re·cep·tor/ (-ter)

1. a molecule on the surface or within a cell that recognizes and binds with specific molecules, producing a specific effect in the cell; e.g., the cell-surface receptors for antigens or cytoplasmic receptors for steroid hormones.

2. a sensory nerve ending that responds to various stimuli.

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a-adrenergic receptors  adrenergic receptors that respond to norepinephrine and to such blocking agents as phenoxybenzamine. They are subdivided into two types: a1, found in smooth muscle, heart, and liver, with effects including vasoconstriction, intestinal relaxation, uterine contraction and pupillary dilation, and a2, found in platelets, vascular smooth muscle, nerve termini, and pancreatic islets, with effects including platelet aggregation, vasoconstriction, and inhibition of norepinephrine release and of insulin secretion.

adrenergic receptors  receptors for epinephrine or norepinephrine, such as those on effector organs innervated by postganglionic adrenergic fibers of the sympathetic nervous system. Classified as a and ß.

alpha-adrenergic receptors  a.

ß-adrenergic receptors , beta-adrenergic receptors adrenergic receptors that respond particularly to epinephrine and to such blocking agents as propranolol. They are subdivided into two basic types: ß1, in myocardium and causing lipolysis and cardiac stimulation, and ß2, in smooth and skeletal muscle and liver and causing bronchodilation and vasodilation. The atypical type ß3 may be involved in lipolysis regulation in adipose tissue.

cholinergic receptors  cell-surface receptor molecules that bind the neurotransmitter acetylcholine and mediate its action on postjunctional cells.

complement receptors  cell-surface receptors for products of complement reactions, playing roles including recognition of pathogens, phagocytosis, adhesion, and clearance of immune complexes. The best characterized are C1–C4, which bind C3 fragments already bound to a surface.

cutaneous receptor  any of the various types of sense organs found in the dermis or epidermis, usually a mechanoreceptor, thermoreceptor, or nociceptor.

cytokine receptors  membrane-spanning proteins that bind cytokines via extracellular domains, acting to convert an extracellular signal to an intracellular one.

H1 receptors , H2 receptors see histamine.

joint receptor  any of several mechanoreceptors that occur in joint capsules and respond to deep pressure and to other stimuli such as stress or change in position.

muscarinic receptors  cholinergic receptors that are stimulated by the alkaloid muscarine and blocked by atropine; they are found on automatic effector cells and on central neurons in the thalamus and cerebral cortex.

muscle receptor  a mechanoreceptor found in a muscle or tendon.

nicotinic receptors  cholinergic receptors that are stimulated initially and blocked at high doses by the alkaloid nicotine and blocked by tubocurarine; they are found on automatic ganglion cells, on striated muscle cells, and on spinal central neurons.

nonadapting receptor  a mechanoreceptor, such as a nociceptor, that responds to stimulation with a continual steady discharge and little or no accommodation over time.

olfactory receptor  a chemoreceptor in the nasal epithelium that is sensitive to stimulation, giving rise to the sensation of odors.

opiate receptor , opioid receptor any of a number of receptors for opiates and opioids, grouped into at least seven types on the basis of their substrates and physiological effects.

orphan receptor  a protein identified as a putative receptor on the basis of its structure but without identification of possible ligands or evidence of function.

pain receptor  nociceptor.

rapidly adapting receptor  a mechanoreceptor that responds quickly to stimulation but that rapidly accommodates and stops firing if the stimulus remains constant.

sensory receptor  receptor (2).

slowly adapting receptor  a mechanoreceptor that responds slowly to stimulation and continues firing as long as the stimulus continues.

stretch receptor  a sense organ in a muscle or tendon that responds to elongation.

tactile receptor  a mechanoreceptor for the sense of touch.

thermal receptor  thermoreceptor.

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re·cep·tor (r-sptr)

n.

1. A specialized cell or group of nerve endings that responds to sensory stimuli.

2. A molecular structure or site on the surface or interior of a cell that binds with substances such as hormones, antigens, drugs, or neurotransmitters.

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Receptor

A molecular structure in a cell or on the surface of a cell that allows binding of a specific substance that causes a specific physiologic response.

Mentioned in: Adrenergic Blockers, Methadone

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receptor(s) (rēsep´tur),

n a site or location within a cell or its membrane that combines with a haptophore group of a toxin, drug, enzyme, hormone, or other substance and that may elicit a specific or general response; a sensory nerve terminal that responds to stimuli of various kinds.

receptor, sensory,

n receptor system built on the theory that receptor organs are specialized and respond to the law of specific nerve energies; i.e., each type of end-organ, no matter what stimulus is applied, will respond (if it responds) with only a single appropriate type of sensation. Common experience shows this to be true; e.g., when a person receives a blow to the eye, light is experienced as a consequence of the blow. Another factor is that the impulse will travel in only one direction, from the receptor organ back to the central nervous system. The receptor system is thus the summation in the brain of all the sensory stimuli that come from the special senses, general senses, mucous membrane, skin, and deeper tissues and is the basis for instruction sent to the musculoskeletal system for action, as in the masticatory phenomenon.

receptors, adrenergic,

n alpha and beta “units” associated with sympathetic neuroeffectors that react with sympathomimetic drugs to elicit the response of the effector cells.

receptors, beta,

n sites on some cell membranes in the sympathetic nervous system that either activate or block the normal functions of the cell by binding with epinephrine (adrenaline). Cells with beta receptors normally control physiologic responses such as heart rate.

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receptor

1. a molecule on the surface or within a cell that recognizes and binds with specific molecules, producing some effect in the cell, e.g. the cell-surface receptors of immunocompetent cells that recognize antigens, complement components or lymphokines, or those of neurons and target organs that recognize neurotransmitters or hormones; see also opioid receptors.

2. a sensory nerve ending that responds to various stimuli, e.g. arterial stretch, baroreceptors, cold, Golgi tendon organs, joint, muscle and tendon, olfactory, retinal, taste and warmth.

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receptor activation

the cell of a sensory receptor responds to a specific energy change in its environment and initiates a corresponding sensory input.

adrenergic r's

receptors for epinephrine or norepinephrine, such as those on effector organs innervated by postganglionic adrenergic fibers of the sympathetic nervous system. Classified as a-adrenergic receptors, which are stimulated by norepinephrine, and ß-adrenergic receptors, which are stimulated by epinephrine. See also adrenergic receptors.

autonomic r's

includes adrenergic and muscarinic receptors.

cholinergic r's

receptor sites on effector organs innervated by cholinergic nerve fibers and which respond to the acetylcholine secreted by these fibers. There are two types: muscarinic receptors and nicotinic receptors.

complement receptor

a cell-surface receptor capable of binding activated complement components. For example, component C3b is bound to neutrophils, B lymphocytes and macrophages.

dopamine r's

there are dopamine-inhibitory and dopamine-excitatory receptors.

drug receptor

a component of tissue with which a drug reacts. Classified according to the type of drugs that react with them.

Fc receptor

bind immunoglobulins via Fc part of the molecule.

histamine r's

receptors for histamine, classified as H1-receptors, which produce bronchoconstriction and contraction of the gut and are blocked by antihistamines, such as mepyramine or chlorpheniramine, and H2-receptors, which produce gastric acid secretion and are blocked by H₂-receptor blockers, such as cimetidine.

muscarinic receptor

see muscarinic receptors.

nicotinic receptor

see nicotinic receptors.

peripheral receptor

sensory receptors including cutaneous warm and cold, dermoreceptors touch and pain plus receptors in the mucosae.

sensory receptor

an endorgan at the end of an afferent neuron which is capable of stimulation by a specific change, physical or chemical, in the internal or external environment of the patient.

toll-like r's

a family of transmembrane proteins that differentially recognize pathogen-associated molecular patterns through an extra cellular domain and initiate inflammatory signaling pathways through an intracellular domain; they play a central role in the innate immune response to pathogens.

receptor tyrosine kinases

a large class of cell-surface receptors with tyrosine-specific protein kinase activity.