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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 ?
1947) The respiratory responses to anoxemia of unanesthetized dogs with chronically denervated aortic and carotid chemoreceptors and their causes.
Several studies suggested that sensilla chaetica function as contact chemoreceptors and mechanoreceptors because they arise from a socket and possess a terminal pore (Altner & Prillinger 1980; Van der Pers et al.
A slight decrease in antennular flicking was usually observed during the walking phase, as if the rapid up and down movements of the aesthetasc-bearing flagellum, necessary for resetting chemoreceptor sensitivity, were somehow compensated by the movements of the animal.
The peripheral chemoreceptors only respond to partial pressure of gas and not to gas content.
Thus, antennular chemoreceptors make possible the detection of low-molecular weight stimuli, such as olfactory sex pheromones or food attractants, at some distance from the source of the odor stimulus.
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).
We can also have an internal reset, if you will, of the chemoreceptors on the brain that can lead to dyspnea and central sleep apnea.
The marked metabolic acidosis was producing substantial stimulation of the central chemoreceptors (11).
Sensilla coeloconica are considered as hygrothermoreceptors or contact chemoreceptors [10].
Control is regulated by chemoreceptors which respond to changes in the chemical composition of blood (West 2008).
There are more than five sense receptors if we include enteroreceptors, such as proprioceptors (tension receptors) in muscles, tendons and joint capsules, or chemoreceptors for detecting blood pH, C[O.