The hypthalamus is defined as a portion of the brain that contains a number of small nuclei. These nuclei have a variety of different functions. One of the most important functions within this is the inking of the nervous system to the endocrine system.
According to Wikipedia, one of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland. When the thyroid receives thyroid stimulating hormone (TSH) from the pituitary gland it produces triiodothyronine which is commonly referred to as T3, thyroxine which is commonly known as T4, and calcitonin.
The hypothalamus releases growth hormone-releasing hormone (GHRH) to stimulate the pituitary gland to release growth hormone (GH). GH acts on the liver to produce insulin-like growth factor 1 (IGF-1), which plays a key role in promoting growth throughout childhood and adolescence. Additionally, the hypothalamus regulates the timing of puberty by secreting gonadotropin-releasing hormone (GnRH), which stimulates the release of sex hormones that influence growth and development.