Negative Feedback Systems In Biology

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Register to read the introduction… The body has particular features such as the skin and circulatory system, which helps its survival against the environment. The metabolism is able to adjust to internal and external changes that occur.

BIOLOGICAL FEEDBACK SYSTEMS IN HOMEOSTASIS ------------------------------------------

Negative Feedback -----------------

According to G.W. Stout and N.P.O Green in 'Work out Biology, A level' negative feedback opposes any detected tendency away from the optimal level and returns it to the optimal level.

Homeostasis is maintained by control systems, which detect and respond to changes in the internal environment. Analogy is often made with domestic heating and cooling systems where a fall in temperature will trigger the thermostat, fire up the boiler and heat up the radiators until the temperature rises and then the thermostat will switch off. A rise in temperature will trigger the thermostat to switch off the boiler until the temperature is normal again. A control system has three basic components:

A detector (receptors)-detects the stimulus disturbing the body,
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An example is the mechanism of blood clotting in a blood vessel. Once a blood vessel has been damaged, platelets immediately begin to cling to the damaged site and release chemicals that attract more platelets. This rapidly growing pileup of platelets initiates the sequence of events that finally forms a clot. (8)


Source: Marieb EN, 2003, Human Anatomy & Physiology, sixth edition, San Francisco, Pearson Benjamin Cummings, page 12

Homeostatic imbalance in this case could be fatal, for example if the clotting mechanism fails on the large central artery that supplies the brain, the brain will be short of oxygen (hypoxia) leading to a stroke and if not treated immediately it will result in death.

Another examples of positive feedback include labour contractions during birth and lactation from the mother's nipple. The importance of homeostasis is again demonstrated in these mechanisms.

Communication -------------

Communication within the body is crucial for homeostasis. Communication is accomplished mainly by the nervous and endocrine systems, which use electrical impulses delivered by nerves

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