Chemoreceptors , more recently called chemosensors , belong to the sensory cells ( receptors ) and are specialized in the perception of chemical substances transported in the air or dissolved in liquids . They therefore play a central role in the sense of smell and taste .
While humans have only about 320 different chemoreceptors, sheepdogs , for example, have more than 1200 different chemoreceptors that detect molecules .
Chemoreceptors are involved in the regulation of breathing , vascular tone and the acid-base balance of the human body:
- Central chemoreceptors in the circulation center in the brainstem ( reticular formation ) measuring pH and CO 2 - partial pressure of the cerebrospinal fluid ,
- Peripheral chemoreceptors are located in the glomera carotica and the glomera aortica . They are for protons ( pH ), potassium , O 2 - partial pressure , CO 2 partial pressure sensitive .
The peripheral chemoreceptors are very sensitive to oxygen. If the O 2 partial pressure falls below 110 mm Hg (“O 2 threshold”), they trigger excitations in the afferent nerves that lead to the respiratory center .
In addition to the chemoreceptor trigger zone in the area postrema at the floor of the fourth ventricle , chemosensors in the mucous membrane of the upper gastrointestinal tract also play an important role in triggering vomiting . They talk about bacterial toxins , emetine (an alkaloid from the emetic root , which is used as a syrup to induce therapeutic vomiting in unconscious people), more concentrated saline solution, copper sulfate and the like. a. Substances.
Microplastics have a negative effect on the chemosensors of the large periwinkle and lead to a reduced or no escape reaction from predators.
- ↑ Laurent Seuront: Microplastic leachates impair behavioral vigilance and predator avoidance in a temperate intertidal gastropod. In: Biology Letters. 14, 2018, p. 20180453, doi : 10.1098 / rsbl.2018.0453 .