Feedback Loops

Hormone production is regulated by a number of factors, including other hormones, the activation of the nervous system, and humoral stimuli, concentration changes that occur in extracellular fluids like blood.

In most cases excessive hormone production is prevented by negative feedback, a loop that starts with a stimulus, inducing the release of a particular substance, like a hormone, to maintain a certain level, before triggering a signal that results in a decrease in further release of the hormone.

For example, an increase in blood glucose levels releases the hormone insulin from the pancreas into the blood stream, delivering insulin to cells throughout the body. Insulin then causes the cells to take up glucose, which lowers blood sugar levels, and in turn signals the pancreas to stop producing insulin.