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Any sense organ that responds to chemical stimuli.



a specialized sensory cell or cellular structure, for example, a nerve ending, by which animals and humans perceive chemical stimuli, including metabolic changes. The effect of chemical agents on the receptors, like that of other stimuli on the corresponding receptor cells, gives rise to bioelectric potentials in the chemoreceptors and related nerve cells. Some chemoreceptors are highly selective, reacting only to a single substance or to a small group of substances; examples are the chemoreceptors in insects that are sensitive to pheromenes or receptors that react to carbon dioxide.

External (sensory) chemoreceptors signal fluctuations in the pH and ion composition of water and in the composition of atmospheric gases. They also indicate the presence in the environment or oral cavity of nutrients, caustic or toxic substances, and special chemical signals exchanged between living organisms. Internal chemoreceptors, which are a type of interoceptor, are sensitive to the chemical constituents of blood and other internal fluids.

From the evolutionary standpoint, chemoreceptors are probably the most ancient receptor formations. The sensory chemoreceptors of vertebrates include the olfactory and gustatory cells situated in the organs of smell and taste, as well as the free nerve endings in the skin that perform the function of “general chemical sensation.” Olfactory and gustatory chemoreceptors are also distinguished on the basis of functional and morphological characteristics in some invertebrates, for example, insects. However, this distinction cannot always be made in the case of invertebrates, especially aquatic forms.

In molecular biology, the term “chemoreceptor” is also used to designate a subcellular formation, that is, a specialized macromolecular structure arranged on the external surface of the cell membrane, that interacts with the molecules of chemical stimuli. The term is also used to designate similar receptors in protozoans.


References in periodicals archive ?
Tarsal chemoreceptors may respond to vapours and the most noticeable effect of repellent vapours on flight posture of Ae.
Shapiro, Alley, and Maddock then became curious about the location of the chemoreceptor protein in Caulobacter as well as E.
Electrophysiological responses of the chemoreceptor neurones in the antennal taste sensilla to plant alkaloids and glucosides in a granivorous ground beetle.
Effects of carotid endarterectomy on carotid chemoreceptor and baroreceptor functions in man.
Facilitating the oxyhemoglobin dissociation shift is an increase in chemoreceptor control of ventilation brought on by decreased bicarbonate in the cerebrospinal fluid and excretion of bicarbonate by the kidneys (1).
Patients with OSA have been shown to have a high level of sympathetic activity during sleep possibly due to the episodes of hypoxia and hypercapnia that they experience triggering chemoreceptor reflexes.
Alternatively, higher stimulation frequency by soluble pheromone to the chemoreceptors in the group-living species than in the pair-living species may be one of the major factors to shape the difference in aesthetasc number of shrimp in the 2 social systems.
CBTs are slowly growing and generally benign tumors arising from chemoreceptor tissues in carotid bifurcation.
Chemoreceptor cells are responsible for changes in blood pH, oxygen tension, and carbon dioxide content (JOHNSON, 1968; CAPEN, 2007).
The chemoreceptor trigger zone (CTZ) located in the postrema surface of the brain also can stimulate the vomiting center indirectly.
Gan et al suggested several other mechanisms for the antiemetic action of propofol, including direct depressant effects on the chemoreceptor trigger zone, the vagal nuclei and other centres implicated in nausea and vomiting (20).
Although being quite different from clinical hypoxia, it is well known that one of the first responses to hypobaric hypoxia is increased heart rate as a result of carotid and aortic chemoreceptor stimulation (1).