<P> The hypothalamus (from Greek ὑπό, "under" and θάλαμος, thalamus) is a portion of the brain that contains a number of small nuclei with a variety of functions . One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland (hypophysis). </P> <P> The hypothalamus is located below the thalamus and is part of the limbic system . In the terminology of neuroanatomy, it forms the ventral part of the diencephalon . All vertebrate brains contain a hypothalamus . In humans, it is the size of an almond . </P> <P> The hypothalamus is responsible for the regulation of certain metabolic processes and other activities of the autonomic nervous system . It synthesizes and secretes certain neurohormones, called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones . The hypothalamus controls body temperature, hunger, important aspects of parenting and attachment behaviours, thirst, fatigue, sleep, and circadian rhythms . </P> <P> The hypothalamus is a brain structure made up of distinct nuclei as well as less anatomically distinct areas . It is found in all vertebrate nervous systems . In mammals, magnocellular neurosecretory cells in the paraventricular nucleus and the supraoptic nucleus of the hypothalamus produce neurohypophysial hormones, oxytocin and vasopressin . These hormones are released into the blood in the posterior pituitary . Much smaller parvocellular neurosecretory cells, neurons of the paraventricular nucleus, release corticotropin - releasing hormone and other hormones into the hypophyseal portal system, where these hormones diffuse to the anterior pituitary . </P>

The region in brain portion that controls hunger signals