Alien-Interiew-Footnote-links
"...chemical-electrical trigger" mechanism"
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- Electrotaxis
| 207 "...chemical-electrical trigger" mechanism" "A taxis (plural taxes) is an innate behavioural response by an organism to a stimulus. A taxis differs from a tropism (turning response, often growth towards or away from a stimulus) in that the organism has motility and demonstrates guided movement towards or away from the stimulus. It also differs from a kinesis, a non-directional change inactivity in response to a stimulus that results in the illusion of directed motion due to different rates of activity depending on stimulus intensity. For example, flagellate protozoans of the genus Euglena move towards alight source. Here the directional stimulus is light, and the orientation movement is towards the light. This reaction or behaviour is a positive one to light and specifically termed "positive pho- totaxis", since phototaxis is a response to alight stimulus, and the organism is moving towards the stimulus. If the organism moves away from the stimulus, then the taxis is negative. Many types of taxis have been identified and named using prefices to specify the stimulus that elicits the response. These include anemotaxis (stimulation by wind, barotaxis (pressure, chemotaxis (chemicals, galvanotaxis (electrical current, geotaxis (gravity, hydro- taxis (moisture, phototaxis (light, rheotaxis (fluid flow, thermotaxis (temperature changes) and thigmotaxis (physical contact. Chemotaxis is a migratory response elicited by chemicals. Unicellular (e.g. protozoa) or multicellular (e.g. worms) organisms are targets of the substances. A concentration gradient of chemicals developed in a fluid phase guides the vectorial movement of responder cells or organisms. Electrotaxis is directional movement of motile cells in response to a electric field. It has been suggested that by detecting and orientating themselves toward the electric fields. This notion is based on 1) the existence of measurable electric fields that naturally occur during wound healing, development and regeneration and 2) cells in cultures respond Download 2 Mb. Share with your friends:
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