Hormone: A chemical substance produced in the body that controls and regulates the activity of certain cells or organs.
Hypothalamus: A region of the brain responsible for producing hormones that control bodily functions such as temperature regulation, thirst, hunger, sleep, mood, sex drive, and release of other hormones within the body.
Pituitary Gland: A small endocrine system organ that produces hormones influencing various parts of the body - growth & development; functioning of other endocrine glands; regulation processes like metabolism & reproduction.