The hypothalamus is a small yet very important part of the brain below the thalamus (hypo=below). It is part of the control mechanism for many of the endocrine glands. Through its connection with the pituitary gland through the infundibulum the hypothalamus directs the pituitary's secretions, which in turn direct many other endocrine glands. The hypothalamus also coordinates many autonomic and visceral functions such as control of blood glucose, heart rate and respiration in response to stresses, control of thermoregulation, the perception of hunger, thirst, control of electrolyte and water balance, and the sleep-wake cycle.