The hypothalamus serves as a linkage between the nervous system and endocrine system through the pituitary gland or the hypophysis. The hypophysis is a pea-sized gland that is located at the base of the human brain just below the hypothalamus, and it secretes important hormones in the human body.
For example, the thyroid regulation, the hypothalamus secretes the thyrotropin-releasing hormone or known as TRH. This type of hormone stimulates the pituitary gland (hypophysis) in order to produce thyroid-stimulating hormone or TSH. Now, this hormone, TSH, stimulates the thyroid gland so that it will secrete hormones. When the level of thyroid hormones is high enough, the hormones will now feedback to stop the hypothalamus from secreting TRH and the pituitary from secreting TSH. When the TSH does not stimulate, the thyroid gland will stop secreting hormones. Eventually, the level of thyroid hormones will begin to fall too low.