|
Search over 100 encyclopedias and dictionaries: |
Research categories | Follow us on Twitter |
Research categories
View all topics in the newsView all reference sources at Encyclopedia.com |
|||
thermogenesis
thermogenesis The production of heat within tissues to raise body temperature. It occurs especially in birds and mammals, animals that maintain their temperature within a narrow range (i.e. endotherms), but is also found in some ‘cold-blooded’ vertebrates and invertebrates. There are two types of thermogenesis, of which the more familiar is shivering. This involves repeated rapid contractions of antagonistic sets of skeletal muscles, which produce little net movement so that most of the chemical energy (in the form of ATP) is converted to heat rather than mechanical work. Nonshivering thermogenesis takes place in fat cells (adipose tissue) and involves the breakdown of stored fat to generate heat in situ instead of its being transported to the liver for conversion to ATP. This process is activated by the sympathetic nervous system and is accomplished in two ways: nonproductive cyclical active transport of ions across the fat-cell plasma membrane and uncoupling of electron transport from ATP synthesis within the fat-cell mitochondria. The net result is release of energy from existing ATP and oxidation of fat to produce heat instead of ATP. Certain mammals have deposits of a special adipose tissue called brown fat that is adapted to provide the body with bursts of intense heat. Stimulation of brown fat oxidation enables rapid warming during the arousal of hibernating animals, for example. Brown fat deposits are also present in human babies and other neonate mammals, to help protect them against hypothermia.
|
|
|
Cite this article
"thermogenesis." A Dictionary of Biology. 2004. Encyclopedia.com. 29 May. 2012 <http://www.encyclopedia.com>. "thermogenesis." A Dictionary of Biology. 2004. Encyclopedia.com. (May 29, 2012). http://www.encyclopedia.com/doc/1O6-thermogenesis.html "thermogenesis." A Dictionary of Biology. 2004. Retrieved May 29, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-thermogenesis.html |
|
thermogenesis
thermogenesis Increased heat production by the body, either to maintain body temperature (by shivering or non‐shivering thermogenesis) or in response to food intake, diet‐induced thermogenesis. See also brown adipose tissue.
|
|
|
Cite this article
DAVID A. BENDER. "thermogenesis." A Dictionary of Food and Nutrition. 2005. Encyclopedia.com. 29 May. 2012 <http://www.encyclopedia.com>. DAVID A. BENDER. "thermogenesis." A Dictionary of Food and Nutrition. 2005. Encyclopedia.com. (May 29, 2012). http://www.encyclopedia.com/doc/1O39-thermogenesis.html DAVID A. BENDER. "thermogenesis." A Dictionary of Food and Nutrition. 2005. Retrieved May 29, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O39-thermogenesis.html |
|
Search over 100 encyclopedias and dictionaries:
HighBeam™ Research, Inc. © Copyright 2012. All rights reserved.
The Encyclopedia.com advertising network includes:
