Basic Endocrine Regulation

Overview
  • Powerful mechanisms ensure that hormone levels are matched to physiological needs. Most hormones are regulated by Feedback Control mechanisms where the physiological effect of the hormone is able to regulate the secretion of the hormone. In most cases, the physiological effect of the hormone feeds back to inhibit the hormones release, referred to as Negative Feedback. In a few cases, the physiological effect of the hormone feeds back to promote the hormones release, referred to as Positive Feedback. In general, feedback loops require that the hormone-releasing organ directly or indirectly sense the physiological effect of the hormone itself.
Endocrine Negative Feedback
  • The release of most hormones is regulated by basic negative feedback control circuits. Briefly, these circuits ensure that successful physiological action of the hormone results in inhibition of the hormone's release. Negative feedback loops are stabilizing, meaning that their operation results in relatively stable levels of the regulated molecules. Nearly all of the hormones that will be discussed are regulated by negative feedback control circuits.
Endocrine Positive Feedback
  • In a very few cases hormones are regulated by positive feedback control circuits. Briefly, these circuits ensure that successful physiological action of the hormone results in even more hormone release. Positive feedback loops are destabilizing, meaning that their operation results in huge spikes of the regulated molecules. The main example of positive feedback is the hormonal control of ovulation.