Chemoreceptor


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chemoreceptor

[‚kē·mō·ri′sep·tər]
(physiology)
Any sense organ that responds to chemical stimuli.

Chemoreceptor

 

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.

A. V. MINOR

References in periodicals archive ?
On the other hand, in contrast to aortic denervation, sino-aortic denervation, as usually performed, also destroys carotid chemoreceptors and results in hypoventilation, which by itself induces chronic hypoxia with its consequent chronic lowering of blood pressure (22,23).
Histology revealed chemodectomas characterized by extensive sheets of neoplastic chemoreceptor cells that were divided into various lobules by connective tissue; these were further subdivided into smaller nest-like structures by thin strands of fibrous septae.
Peripheral chemoreceptors. Breathing, or ventilation, is the movement of air in and out of the lungs.
The effect of blood pressure upon chemoreceptor discharge to hypoxia, and the modification of this effect by the sympathetic-adrenal system.
The chemoreceptor trigger zone in the brainstem employs dopamine D2 and serotonin (5HT3) receptors to control the vomiting reflex, therefore drugs that modulate these receptors affect nausea and vomiting.
We suggest that [O.sub.2]-sensing TRP channels play key roles in the molecular mechanisms that underlie the [O.sub.2]-sensing ability of chemoreceptor (or chemoreceptor-like) cells that are ubiquitous in a variety of tissues and organs.
Molecular evolution of the insect chemoreceptor gene superfamily in Drosophila melanogaster.
Its function is to act as a chemoreceptor in the blood.
Anker et al., "Peripheral chemoreceptor hypersensitivity: an ominous sign in patients with chronic heart failure," Circulation, vol.
Vomiting occurs after stimulation of either the vomiting center (VC), a central "control center" in the medulla near the respiratory center, or the chemoreceptor trigger zone (CTZ) in the area postrema on the floor of the fourth ventricle.
Antiemetic agents are the most common intervention in the management of treatment-related nausea and vomiting (N&V) that completely block the peripheral neuroreceptors and the chemoreceptor trigger zone (CTZ) that are known to contain receptors for serotonin, histamine (H1 and H2), dopamine, acetylcholine, opioids, and numerous other endogenous neurotransmitters.
This article will describe the hypercapnic and associated studies used to study and quantify central and peripheral chemoreceptor control of ventilation or respiratory drive.