hypothalamus hypothalamus the hypothalamus (from ancient greek ὑπό (hupó) 'under', and θάλαμος (thálamos) 'chamber') is a part of the brain that contains a number of small nuclei with a variety of functions. one of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. 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. hypothalamuslocation of the human hypothalamuslocation of the hypothalamus (blue) in relation to the pituitary and to the rest of the braindetailspart ofbrainidentifierslatinhypothalamusmeshd007031neurolex idbirnlex_734ta98a14.1.08.401 a14.1.08.901ta25714fma62008anatomical terms of neuroanatomy the hypothalamus is responsible for regulating 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 hormones from the pituitary gland. the hypothalamus controls body temperature, hunger, important aspects of parenting and maternal attachment behaviours, thirst, fatigue, sleep, and circadian rhythms. structure 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. hypothalamic nuclei are located within these specific regions and 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. nuclei the hypothalamic nuclei include the following: list of nuclei, their functions, and the neurotransmitters, neuropeptides, or hormones that they utilize region area nucleus function anterior (supraoptic) preopticpreoptic nucleus thermoregulation medial medial preoptic nucleus regulates the release of gonadotropic hormones from the adenohypophysis contains the sexually dimorphic nucleus, which releases gnrh, differential development between sexes is based upon in utero testosterone levels thermoregulation supraoptic nucleus vasopressin release oxytocin release paraventricular nucleus thyrotropin-releasing hormone release corticotropin-releasing hormone release oxytocin release vasopressin release somatostatin round anterior hypothalamic nucleus thermoregulation panting sweating thyrotropin inhibition suprachiasmatic nucleus circadian rhythms lateral lateral nucleussee lateral hypothalamus § function – primary source of orexin neurons that project throughout the brain and spinal cord middle (tuberal) medial dorsomedial hypothalamic nucleus blood pressure heart rate gi stimulation ventromedial nucleus satiety neuroendocrine control arcuate nucleus growth hormone-releasing hormone (ghrh) feeding dopamine-mediated prolactin inhibition laterallateral nucleussee lateral hypothalamus § function – primary source of orexin neurons that project throughout the brain and spinal cord lateral tuberal nuclei posterior (mammillary) medial mammillary nuclei (part of mammillary bodies) memory posterior nucleus increase blood pressure pupillary dilation shivering vasopressin release lateral lateral nucleussee lateral hypothalamus § function – primary source of orexin neurons that project throughout the brain and spinal cord tuberomammillary nucleus arousal (wakefulness and attention) feeding and energy balance learning memory sleep