The control/regulation is achieved through positive and negative feedback mechanisms through feedback loops connecting the response to the initial stimulus. In negative feedback, the effector response reduces the initial stimulus, and eventually the response ceases.

This feedback mechanism prevents overreaction by the system and wild fluctuations in the variable being regulated. Negative feedback operates in many endocrine and nervous pathways, especially those involved in maintaining homeostasis. Negative feedback contributes to the hormonal control of blood calcium and glucose levels.

In contrast to negative feedback, which dampens the stimulus, positive feedback reinforces the stimulus and leads to an even greater response. The neurohormone pathway that regulates the release of milk by a nursing mother is an example of positive feedback. Suckling stimulates sensory nerve cells in the nipples, which send nervous signals that eventually reach the hypothalamus, the control center. An outgoing signal from the hypothalamus triggers the release of the neurohormone oxytocin from the posterior pituitary gland. Oxytocin then causes the mammary glands to secrete milk. The release of milk in turn leads to more suckling and stimulation of the pathway, until the baby is satisfied.