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. These hormones are released into the blood in the posterior pituitary. In mammals, magnocellular neurosecretory cells in the paraventricular nucleus and the supraoptic nucleus of the hypothalamus produce neurohypophysial hormones, oxytocin and vasopressin. It is found in all vertebrate nervous systems. Hypothalamic nuclei are located within these specific regions and areas.
The hypothalamus is divided into three regions (supraoptic, tuberal, mammillary) in a parasagittal plane, indicating location anterior-posterior and three areas (periventricular, medial, lateral) in the coronal plane, indicating location medial-lateral. The hypothalamus controls body temperature, hunger, important aspects of parenting and maternal attachment behaviours, thirst, fatigue, sleep, and circadian rhythms. It synthesizes and secretes certain neurohormones, called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of hormones from the pituitary gland. The hypothalamus is responsible for regulating certain metabolic processes and other activities of the autonomic nervous system. All vertebrate brains contain a hypothalamus.
In the terminology of neuroanatomy, it forms the ventral part of the diencephalon.
The hypothalamus is located below the thalamus and is part of the limbic system. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus (from Ancient Greek ὑπό ( hupó) 'under', and θάλαμος ( thálamos) 'bed') is a part of the brain that contains a number of small nuclei with a variety of functions.
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