- Sensory receptor
sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of an organism. In response to stimuli the sensory receptor initiates sensory transductionby creating graded potentials or action potentials in the same cell or in an adjacent one.
sensory receptors involved in taste and smell contain receptors that bind to specific chemicals. Odor receptors in olfactory receptor neurons, for example, are activated by interacting with molecular structures on the odormolecule. Similarly, tastereceptors (gustatory receptors) in taste buds interact with chemicals in food to produce an action potential.
Other receptors such as
mechanoreceptors and photoreceptors respond to physical stimuli. For example, photoreceptor cells contain specialized proteins such as rhodopsinto transduce the physical energy in light into electrical signals. Some types of mechanoreceptors fire action potentials when their membranes are physically stretched.
The sensory receptor functions as the first component in a sensory system.
Sensory receptors respond to specific stimulus modalities. The stimulus modality to which a sensory receptor responds is determined by the sensory receptor's
The sensory receptor responds to its stimulus modality by initiating sensory transduction. This may be accomplished by a net shift in the initial states of a receptor(see a picture of these putative states [http://www.bio-balance.com/Receptor2.htm] with the biophysical description - link [http://www.bio-balance.com/Graphics.htm] ).
by adequate stimulus
A sensory receptor's adequate stimulus is the stimulus modality for which it possesses the adequate
sensory transductionapparatus. Adequate stimulus can be used to classify sensory receptors:
Ampullae of Lorenzinirespond to electric fields, salinity, and to temperature, but function primarily as electroreceptors
Baroreceptors respond to pressure
Chemoreceptors respond to chemical stimuli
Hydroreceptors respond to changes in humidity
Mechanoreceptors respond to mechanical stressor mechanical strain
Nociceptors respond to damage to body tissues leading to pain perception
Osmoreceptors respond to the osmolarityof fluids (such as in the hypothalamus)
Photoreceptors respond to light
Proprioceptors provide the sense of position
Thermoreceptors respond to temperature, either heat, cold or both
Sensory receptors can be classified by location:
Cutaneous receptors are sensory receptors found in the dermis or epidermis.
Muscle spindles contain mechanoreceptors that detect stretch in muscles.
Somatic sensory receptors near the surface of the skin can usually be divided into two groups based on morphology:
Free nerve endingscharacterize the nociceptors and thermoreceptors and are called thus because the terminal branches of the neuron are unmyelinated and spread throughout the dermisand epidermis.
Encapsulated receptors consist of the remaining types of cutaneous receptors. Encapsulation exists for specialized functioning.
Different sensory receptors are innervated by different types of
nerve fibers. Muscles and associated sensory receptors are innvervated by type I and II sensory fibers, while cutaneous receptorsare innervated by Aβ, Aδ and C fibers.
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Look at other dictionaries:
sensory receptor — receptor (def. 2) … Medical dictionary
sensory receptor — noun an organ having nerve endings (in the skin or viscera or eye or ear or nose or mouth) that respond to stimulation • Syn: ↑sense organ, ↑receptor • Ant: ↑effector (for: ↑receptor) • Derivationally related forms: ↑ … Useful english dictionary
sensory receptor — noun A sensory nerve ending that recognizes a stimulus in the internal or external environment of an organism … Wiktionary
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sensory system — noun 1. a particular sense • Syn: ↑modality, ↑sense modality • Hypernyms: ↑sense, ↑sensation, ↑sentience, ↑sentiency, ↑sensory faculty … Useful english dictionary
sensory transduction — the process by which a sensory receptor converts a stimulus from the environment into an action potential for transmission to the brain. See also organa sensuum under organum … Medical dictionary