The hypothalamus is located in the brain, near the optic chiasm. It secretes hormones that stimulate or suppress the release of hormones in the pituitary gland, in addition to controlling water balance, sleep, temperature, appetite, and blood pressure. Hormones are chemical substances created by the body that control numerous body functions. Most hormones are proteins consisting of amino acid chains.
Some hormones are steroids, fatty cholesterol-produced substances.
The pineal body is located below the corpus callosum, a part of the brain. It produces the hormone melatonin. The pituitary gland is located at the base of the brain. No larger than a pea, the gland controls many functions of the other endocrine glands. The thyroid plays an important role in the body's metabolism.