A chemosensor, also known as chemoreceptor, is a
sensory receptorthat transduces a chemical signal into an action potential. Or, more generally, a chemosensor detects certain chemical stimuli in the environment.
There are two main classes of the chemosensor: direct and distance.
* Examples of "distance chemoreceptors" are:
olfactory receptor neurons in the olfactory system
** neurons in the
vomeronasal organthat detect pheromones
* Examples of "direct chemoreceptors" include
taste budsin the gustatory system
** carotid bodies and aortic bodies that detect changes in
pHinside the body.
Chemoreceptors detect the levels of
carbon dioxidein the blood. To do this, they monitor the concentration of hydrogen ions in the blood, which decreases the pHof the blood. This is a direct consequence of an increase in carbon dioxide concentration, because carbon dioxide becomes carbonic acid in an aqueous environment.
The response is that the inspiratory centre (in the medulla), sends nervous impulses to the external
intercostal musclesand the diaphragm, via the intercostal nerveand the phrenic nerve, respectively, to increase breathing rate and the volume of the lungs during inhalation.
Chemoreceptors which affect breathing rate are broken down into two categories.
central chemoreceptorsare located on the ventrolateral surface of medulla oblongataand detect changes in pH of cerebrospinal fluid. They do not respond to a drop in oxygen, and eventually desensitize.
peripheral chemoreceptors: Aortic bodydetects changes in blood oxygen and carbon dioxide, but not pH, while carotid bodydetects all three. They do not desensitize. Their effect on breathing rate is less than that of the central chemoreceptors.
Chemoreceptors in the
medulla oblongata, carotid arteriesand aortic arch, detect the levels of carbon dioxidein the blood, in the same way as applicable in the Breathing Rate section.
In response to this high concentration, a nervous impulse is sent to the
cardiovascular centrein the medulla, which will then feedback to the sympathetic ganglia, increasing nervous impulses here, and prompting the sinoatrial nodeto stimulate more contractions of the myogenic cardiac muscleincreasing heart rate by causing the secretion of nor-adrenaline directly on to the sinoatrial node.
tastesensation, the tongueis composed of 5 different taste buds: salty, sour, sweet, bitter, and savory. The salty and sour tastes work directly through the ion channels, the sweet and bitter taste work through G protein-coupled receptors, and the savoury sensation is activated by glutamate. Noses in vertebrates and antennae in many invertebrates act as distance chemoreceptors. Molecules are diffused through the air and bind to specific receptors on "olfactory sensory neurons", activating an opening ion channel via G-proteins.
When inputs from the environment are significant to the survival of the organism the input must be detected. As all life processes are ultimately based on
chemistryit is natural that detection and passing on of the external input will involve chemical events. The chemistry of the environment is, of course, relevant to survival, and detection of chemical input from the outside may well articulate directly with cell chemicals.
For example: The emissions of a predator's food source, such as
odors or pheromones, may be in the air or on a surface where the food source has been. Cells in the head, usually the air passages or mouth, have chemical receptors on their surface that change when in contact with the emissions. The change does not stop there. It passes in either chemical or electrochemical form to the central processor, the brainor spinal cord. The resulting output from the CNS ( central nervous system) makes body actions that will engage the food and enhance survival.
SAW Chemosensor [ [http://www3.sympatico.ca/colin.kydd.campbell/ Understanding Surface Acoustic Wave (SAW) Devices for Mobile and Wireless ] ] (Surface Acoustic Wave Chemosensor) is used to analyse gases.
Diffuse chemosensory system
Solitary chemosensory cells
Wikimedia Foundation. 2010.
Look at other dictionaries:
Chemosensor — Unter einem Chemosensor versteht man: einen Chemorezeptor auf Sinneszellen einen Gassensor zum Nachweis von gasförmigen chemischen Verbindungen als elektrochemischen Sensor eine ionenselektive Elektrode einen Biosensor, wenn damit chemische… … Deutsch Wikipedia
chemosensor — noun a cell in a sense organ that can convert a chemical stimulus into some form of action … Wiktionary
Chemosensor — Che|mo|sen|sor [↑ chem ] ↑ Sensor … Universal-Lexikon
Chemoreceptor — A chemoreceptor, also known as chemosensor, is a sensory receptor that transduces a chemical signal into an action potential. In more general terms, a chemosensor detects certain chemical stimuli in the environment. Contents 1 Classes 2 Cellular… … Wikipedia
Radiation chemistry — is a subdivision of nuclear chemistry which is the study of the chemical effects of radiation on matter; this is very different from radiochemistry as no radioactivity needs to be present in the material which is being chemically changed by the… … Wikipedia
Molecular sensor — A molecular sensor or chemosensor is a molecule that interacts with an analyte to produce a detectable change. Molecular sensors combine molecular recognition with some form of reporter so the presence of the guest can be observed. The term… … Wikipedia
Elektronische Nase — Eine Elektronische Nase ist ein technisches System zur Messung von Gerüchen. Zu diesem Zweck erzeugen mikroelektronische Gassensoren elektronische Signale. Der Begriff Elektronische Nase vereint damit das „Erkennen“ von Gerüchen mit der… … Deutsch Wikipedia
Cat — For other uses, see Cat (disambiguation) and Cats (disambiguation). Domestic cat … Wikipedia
Microelectromechanical systems — (MEMS) (also written as micro electro mechanical, MicroElectroMechanical or microelectronic and microelectromechanical systems) is the technology of very small mechanical devices driven by electricity; it merges at the nano scale into… … Wikipedia
Sensory system — See also sense A sensory system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory receptors, neural pathways, and parts of the brain involved in sensory perception. Commonly… … Wikipedia