The hypothalamus is a small region located in the base of the brain just above the brainstem.
It performs the critical function of maintaining homeostasis by regulating blood pressure, temperature, sleep, mood, hunger, and thirst.
The hypothalamus responds to signals sent by the brain or the peripheral nervous system either by controlling the hormone secretion or by the management of the autonomic nervous system.
The autonomic nervous system manages the functioning of the heart and respiration.
Hormones secreted by the hypothalamus act as signals for the pituitary gland to secrete its hormones and perform their function.
For example, the growth hormone-releasing hormone synthesized by the hypothalamus sends messages to the pituitary gland to secrete the growth hormone which in turn is sent to the bones and muscles to stimulate growth.