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Concept
Récepteur (cellule)
Résumé
Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded receptor potentials. This process is called sensory transduction. The cell bodies of the sensory neurons are located in the dorsal ganglia of the spinal cord.
The sensory information travels on the afferent nerve fibers in a sensory nerve, to the brain via the spinal cord. The stimulus can come from exteroreceptors outside the body, for example those that detect light and sound, or from interoreceptors inside the body, for example those that are responsive to blood pressure or the sense of body position.
== Types and function ==
Different types of sensory neurons have different sensory receptors that respond to different kinds of stimuli. There are at least six external and two internal sensory receptors:
Information coming from the sensory neurons in the head enters the central nervous system (CNS) through cranial nerves. Information from the sensory neurons below the head enters the spinal cord and passes towards the brain through the 31 spinal nerves. The sensory information traveling through the spinal cord follows well-defined pathways. The nervous system codes the differences among the sensations in terms of which cells are active.
A sensory receptor's adequate stimulus is the stimulus modality for which it possesses the adequate sensory transduction apparatus. Adequate stimulus can be used to classify sensory receptors:
Baroreceptors respond to pressure in blood vessels
Chemoreceptors respond to chemical stimuli
Electromagnetic radiation receptors respond to electromagnetic radiation
Infrared receptors respond to infrared radiation
Photoreceptors respond to visible light
Ultraviolet receptors respond to ultraviolet radiation
Electroreceptors respond to electric fields
Ampullae of Lorenzini respond to electric fields, salinity, and to temperature, but function primarily as electroreceptors
Hydroreceptors respond to changes in humidity
Magnetoreceptors respond to magnetic fields
Mechanoreceptors respond to mechanical stress or mechanical strain
Nociceptors respond to damage, or threat of damage, to body tissues, leading (often but not always) to pain perception
Osmoreceptors respond to the osmolarity of fluids (such as in the hypothalamus)
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.
Source officielle
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