stretch receptor


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receptor

 [re-sep´tor]
1. a molecule on the cell surface (cell-surface or membrane receptor) or within a cell, usually in its nucleus (nuclear receptor) 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.
2. a sensory nerve ending that responds to various stimuli.
General sense receptors. (From Applegate, 2000.)
α-r's (α-adrenergic r's) alpha-adrenergic receptors.
adrenergic r's receptors for epinephrine or norepinephrine, such as those on effector organs innervated by postganglionic adrenergic fibers of the sympathetic nervous system. There are two types, alpha-adrenergic receptors and beta-adrenergic receptors.
alpha r's (alpha-adrenergic r's) adrenergic receptors found in cardiac muscle and vascular smooth muscle; they are stimulated by norepinephrine and blocked by agents such as phenoxybenzamine. They are subdivided into two types: α1, found in smooth muscle, heart, and liver, with effects including vasoconstriction, intestinal relaxation, uterine contraction and pupillary dilation, and α2, 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. Called also α-receptors and α-adrenergic receptors.
β-r's (β-adrenergic r's) beta-adrenergic receptors.
B cell antigen r's monomeric IgM, IgD, and (on memory cells only) IgG that is attached to the cell membrane of B lymphocytes (B cells); in conjunction with helper T cells, it triggers B cell activation on contact with antigen.
beta r's (beta-adrenergic r's) adrenergic receptors that are stimulated by epinephrine and blocked by agents such as propranolol. They are subdivided into two basic types: β1-receptors are found in the myocardium and cause lipolysis and cardiac stimulation, and β2-receptors are found in smooth and skeletal muscle and liver and cause bronchodilation and vasodilation. A third type, β3, is atypical; it is more sensitive to norepinephrine than to epinephrine, relatively resistant to propranolol blockade, and may be involved in lipolysis regulation in adipose tissue. Called also β-receptors and β-adrenergic receptors.
cell-surface receptor membrane receptor.
cholinergic r's membrane receptors on cells of effector organs, innervated by cholinergic nerve fibers and responsive to the acetylcholine secreted by these fibers. There are two types, muscarinic receptors and nicotinic receptors.
complement receptor a membrane receptor that can bind activated complement components. For example, component C3b binds to complement receptors of neutrophils, B lymphocytes, and macrophages.
estrogen receptor a cellular regulatory protein that binds estrogenic hormones, found particularly in estrogen-sensitive tissues such as the uterus and breast. Cytoplasmic levels are measured in surgically removed breast carcinomas; high levels indicate that a positive response to endocrine therapy is likely.
Fc r's specific membrane receptors for antigen-antibody complexes or aggregated immunoglobulins that bind a site in the Fc portion of the immunoglobulin molecule and may exhibit specificity for particular immunoglobulin classes. Fc receptors are found on B cells, K cells, macrophages, neutrophils, and eosinophils, and, during some developmental stages, on T cells.
histamine r's receptors for histamine. H1-receptors mediate contraction of smooth muscles and dilation of capillaries, causing effects such as bronchoconstriction and contraction of the intestine; they are blocked by antihistamines such as pyrilamine or chlorpheniramine. H2-receptors mediate acceleration of the heart rate and produce gastric acid secretion; they are blocked by agents such as cimetidine.
IgE r's membrane receptors for IgE, found on mast cells and basophils.
insulin r's a type of membrane receptors specific for insulin, found on target cells.
LDL r's (low-density lipoprotein r's) specific receptors for low-density lipoproteins found in coated pits on the surface of mammalian cells. The coated pits are internalized forming coated vesicles from which the receptors are recycled back to the plasma membrane while particles of low-density lipoprotein are transferred to lysosomes where they are degraded, releasing free cholesterol, phospholipids, and amino acids. Genetic defects in LDL receptors are responsible for familial hypercholesterolemia.
membrane receptor a receptor located on or in the membrane of a cell. Called also cell-surface receptor.
muscarinic r's cholinergic receptors on autonomic effector cells (and also on some autonomic ganglion cells and in some central neurons) that are stimulated by muscarine and parasympathomimetic drugs and blocked by atropine.
nicotinic r's cholinergic receptors of autonomic ganglion cells and motor end-plates of skeletal muscle that are stimulated by low doses of nicotine and blockaded by high doses of nicotine or by tubocurarine.
olfactory receptor a specialized sensory nerve-ending sensitive to stimulation giving rise to the sensation of odors; called also osmoreceptor.
Structure of the olfactory receptors. (From Applegate, 2000.)
opiate r's (opioid r's) receptors that combine with particular opiates to create analgesia and certain other effects. Several different ones have been identified and assigned Greek letters; the μ receptor gives superior analgesia, and the κ receptor is associated with a low degree of physical dependency.
pain r's free nerve endings that are receptors for pain.
stretch receptor a sense organ in a muscle or tendon that responds to elongation.
T cell r's the characteristic marker of T lymphocytes (T cells) that recognize specific foreign antigens as well as self MHC antigens; both must be seen simultaneously to trigger T cell activation (see also lymphocyte activation). The receptor is not a complete immunoglobulin molecule but may contain heavy and light chain variable regions.

stretch receptor

stretch receptor

A sensory nerve ending activated by stretching of the part in which it is situated. An example is the muscle spindle stretch receptor.
Stretch receptorclick for a larger image
Fig. 291 Stretch receptor . The stretch receptor of the muscle spindle.

stretch receptor

the receptor for the detection of muscle stretch located in the muscle spindle organ. The receptor is situated centrally and consists of spiral nerve endings (branches of an efferent nerve) surrounding noncontractile muscle fibres. Efferent nerve fibres connect at each end with contractile muscle fibres. Stretching of a muscle causes discharge from spiral nerve endings to the muscle itself thus causing contraction. The more the spindle is stretched the greater the efferent frequency of impulses and consequently the more the muscle contracts. This is the stretch reflex. Muscle spindles occur in numbers up to 30/g of muscle, shoulder and thigh muscles being spindle-poor and more distal muscles being spindle-rich. The largest numbers occur in the head and upper vertebral column.
References in periodicals archive ?
Figure 2A shows the spatial organization of stretch receptors in the thoracic and abdominal segments, where each stretch receptor, except for TSR-1 (Fig.
GI tract distension and stasis: GI, particularly duodenal, distension triggers stretch receptors in the gut wall, stimulating vagal afferent pathways to the CPG.
The significant increase in BHT in the present study is consistent with previous studies.[6-8] In normal breathing after a particular degree of stretching or even before this, stretch receptors in alveoli are stimulated and send information to the respiratory centers so that exhalation sets in.
Our findings that more patients in whom pencil-point spinal needles are inserted either respond to or acknowledge having experienced sensation at the moment of thecal penetration provides strong clinical evidence that the lumbar meninges are well supplied with sensory stretch receptors.
Graziadei (1965) identified elements with morphological characteristics typical of stretch receptors in the intrinsic muscle of the octopus arms.
Sara Diaz and her col leagues in the study proposed that stretch receptors in pulmonary veins release hypovolemia-mediated signals and trigger maximal secretion of antidiuretic hormone.
One alternate atmospheric pressure detection mechanism that has been proposed for mammals is in the function of stretch receptors in the tympanic membrane (Rockley and Hawke, 1992).
It stimulates stretch receptors, followed by an increase in neural traffic to the brain, which results in sympathetic withdrawal and bradycardia and syncope due to hypotension," Dr.
With bulky, high-fiber foods like vegetables, fruits, and whole grains, you get fewer calories per swallow, so there's more time for the stretch receptors in your stomach to make you feel full.
[3] Information from proprioceptive, visual, vestibular, auditory, tactile, and stretch receptors in various organs is integrated to create a picture of the position and movements of the body parts relative to each other and to the environment.
Furthermore, slowly adapting receptors (SAR or stretch receptors) in the airways influence the cough reflex [18, 19].
Surgically exposed nerve endings and muscle stretch receptors activate local spinal reflexes resulting in muscle spasm.