BIO 126 Lecture Notes - Lecture 3: Negative Feedback
8 Apr 2016
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For example, if the body is too cool, the hypothalamus triggers a warming response. In a negative feedback loop the response counteracts, rather than enhances, the deviation from the set point and returns the body"s temperature to its set point. A positive feedback mechanism is the exact opposite of a negative feedback mechanism. With negative feedback, the output reduces the original effect of the stimulus. In a positive feedback system, the output enhances the original stimulus. A good example of a positive feedback system is child birth. During labor, a hormone called oxytocin is released that intensifies and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle goes on until the baby is born. The birth ends the release of oxytocin and ends the positive feedback mechanism. Energy reflects off of and absorbs into materials. Albedo is the fraction of solar energy reflected from the earth back into space.
