# Hypothalamus --- The **hypothalamus** is a region of the [[diencephalon]] of the brain that plays a major function the [[endocrine system]], the [[autonomic nervous system]] and in regulating [[biology|homeostasis]]. It also has a role in the [[limbic system]]. The hypothalamus is located just below the [[thalamus]], and it has the "optic chiasm" coming off it that connects the [[cranial nerves|optic nerve]] to the eyes. It is also connected to the [[pituitary gland]] by a little thingy called the "infundibulum". The hypothalamus has direct control over the pituitary gland—a gland which doesn't do anything on it's own, but just obeys the hypothalamus. ![[hypothalamus.png]] ## Hormones of the Hypothalamus The hypothalamus directly makes several system-wide [[hormone|hormones]], like [[oxytocin]] and [[antidiuretic hormone]]. I think it sends them to the pituitary for storage and release but I'm not sure. The hypothalamus also makes some [[hormone#Types of Hormones|tropic hormones]], which signal other endocrine glands to make other hormones (and sometimes even other tropic hormones) ## Regulating Thyroid Hormone The hypothalamus ultimately regulates the production and release of thyroid hormone by releasing [[thyroid hormone|thyrotropin-releasing hormone]] to the pituitary gland, which then releases [[thyroid hormone|thyroid stimulating hormone]], which tells the thyroid to release [[thyroid hormone]] itself. The hypothalamus releases TRH in the event of such conditions as: - cold temperature - high altitude - low levels of [[thyroid hormone]] in the blood - [[hypoglycemia]] ## Regulating Temperature [[fever]] [[body temperature]] ## Hunger & Thirst The hypothalamus plays a roll in feeling [[hunger|hungry or full]]. There is a small area of the hypothalamus that is called the **"feeding center"**, which triggers the feelings of hunger, and a different area called the **"satiety center"** that inhibits that feeling. The **thirst mechanism** of the hypothalamus is the body's command center for fluid intake. It's triggered when there is an increase of solutes in the [[blood|bloodstream]] and when there is a reduction in [[blood volume]], and when the mouth and throat get dry due to lack of [[salivary glands|saliva]], due to a lack of fluids in the blood. The thirst mechanism prompts us to drink, but it also releases [[kidneys|ADH]] to trigger the kidney's to retain some water. The hypothalamus "listens" [[hunger#The Hormones of Hunger|hormone levels]] and for signals from [[neurons]] lining the mouth, throat, and esophagus to gage if it should activate hunger or satiety. For example, chewing and swallowing food stimulates those nerve cells which then stimulates the satiety center. ___