Sierra Acai Company
Sierra Acai Company
Open 7 Days a Week
MonaVie Independent Distributor
Distributor Training
Shop Online
Enroll Now
Buy Wholesale and maintain an Active status for 2 months and we will refund your $39 Distributor Fee
Friends
Buy Wholesale and maintain an Active status for 2 months and we will refund your $39 Distributor Fee
09-SEPTEMBER-2008 02:07:44 - Hypothalamus Redirected from Hypothalamic Brain: Hypothalamus Location of the human hypothalamus Dienchephalon Latin hypothalamus Gray's subject #189 812 NeuroNames hier-358 MeSH Hypothalamus The hypothalamus links the nervous system to the endocrine system via the pituitary gland hypophysis. The hypothalamus, from Greek ὑποθαλαμος = under the thalamus is located below the thalamus, just above the brain stem. This brain region occupies the major portion of the ventral diencephalon. It is found in all mammalian brains. In humans, it is roughly the size of an almond. The hypothalamus is responsible for certain metabolic processes and other activities of the Autonomic Nervous System. It synthesizes and secretes neurohormones, often called hypothalamic-releasing hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones. It also controls the fight-or-flight response and sexual desire. The hypothalamus controls body temperature, hunger, thirst, 1 fatigue, anger, and circadian cycles. Contents 1 Inputs 1.1 Olfactory stimuli 1.2 Blood-borne stimuli 1.3 Steroids 1.4 Neural inputs 2 Nuclei 3 Outputs 3.1 Neural projections 3.2 Endocrine hormones 4 Control of food intake 5 Sexual dimorphism 5.1 Responses to ovarian steroids 5.2 Gonadal steroids in neonatal life of rats 5.3 Androgens in primates 5.4 Other influences upon hypothalamic development 6 Effects of aging on the hypothalamus 7 See also 8 Additional images 9 References 10 External links Inputs The hypothalamus is a complex region in the brain of humans, and even small nuclei within the hypothalamus are involved in many different functions. The paraventricular nucleus for instance contains oxytocin and vasopressin also called antidiuretic hormone neurons which project to the posterior pituitary, but also contains neurons that regulate ACTH and TSH secretion which project to the anterior pituitary, gastric reflexes, maternal behavior, blood pressure, feeding, immune responses, and temperature. The hypothalamus co-ordinates many hormonal and behavioural circadian rhythms, complex patterns of neuroendocrine outputs, complex homeostatic mechanisms,2 and many important behaviours. The hypothalamus must therefore respond to many different signals, some of which are generated externally and some internally. It is thus richly connected with many parts of the CNS, including the brainstem reticular formation and autonomic zones, the limbic forebrain particularly the amygdala, septum, diagonal band of Broca, and the olfactory bulbs, and the cerebral cortex. The hypothalamus is responsive to: Light: daylength and photoperiod for regulating circadian and seasonal rhythms Olfactory stimuli, including pheromones Steroids, including gonadal steroids and corticosteroids Neurally transmitted information arising in particular from the heart, the stomach, and the reproductive tract Autonomic inputs Blood-borne stimuli, including leptin, ghrelin, angiotensin, insulin, pituitary hormones, cytokines, plasma concentrations of glucose and osmolarity etc Stress Invading microorganisms by increasing body temperature, resetting the body's thermostat upward. Olfactory stimuli Olfactory stimuli are important for sex and neuroendocrine function in many species. For instance if a pregnant mouse is exposed to the urine of a 'strange' male during a critical period after coitus then the pregnancy fails the Bruce effect. Thus during coitus, a female mouse forms a precise 'olfactory memory' of her partner which persists for several days. Pheromonal cues aid synchronisation of oestrus in many species; in women, synchronised menstruation may also arise from pheromonal cues, although the role of pheromones in humans is doubted by some. Blood-borne stimuli Peptide hormones have important influences upon the hypothalamus, and to do so they must evade the blood-brain barrier. The hypothalamus is bounded in part by specialized brain regions that lack an effective blood-brain barrier; the capillary endothelium at these sites is fenestrated to allow free passage of even large proteins and other molecules. Some of these sites are the sites of neurosecretion - the neurohypophysis and the median eminence. However others are sites at which the brain samples the composition of the blood. Two of these sites, the subfornical organ and the OVLT organum vasculosum of the lamina terminalis are so-called circumventricular organs, where neurons are in intimate contact with both blood and CSF. These structures are densely vascularized, and contain osmoreceptive and sodium-receptive neurons which control drinking, vasopressin release, sodium excretion, and sodium appetite. They also contain neurons with receptors for angiotensin, atrial natriuretic factor, endothelin and relaxin, each of which is important in the regulation of fluid and electrolyte balance. Neurons in the OVLT and SFO project to the supraoptic nucleus and paraventricular nucleus, and also to preoptic hypothalamic areas. The circumventricular organs may also be the site of action of interleukins to elicit both fever and ACTH secretion, via effects on paraventricular neurons. It is not clear how all peptides that influence hypothalamic activity gain the necessary access. In the case of prolactin and leptin, there is evidence of active uptake at the choroid plexus from blood into CSF. Some pituitary hormones have a negative feedback influence upon hypothalamic secretion; for example, growth hormone feeds back on the hypothalamus, but how it enters the brain is not clear. There is also evidence for central actions of prolactin and TSH. Steroids The hypothalamus contains neurons that react strongly to steroids and glucocorticoids - the steroid hormones of the adrenal gland, released in response to ACTH. It also contains specialised glucose-sensitive neurons in the arcuate nucleus and ventromedial hypothalamus, which are important for appetite. The preoptic area contains thermosensitive neurons; these are important for TRH secretion. Neural inputs The hypothalamus receives many inputs from the brainstem; notably from the nucleus of the solitary tract, the locus coeruleus, and the ventrolateral medulla. Oxytocin secretion in response to suckling or vagino-cervical stimulation is mediated by some of these pathways; vasopressin secretion in response to cardiovascular stimuli arising from chemoreceptors in the carotid sinus and aortic arch, and from low-pressure atrial volume receptors, is mediated by others. In the rat, stimulation of the vagina also causes prolactin secretion, and this results in pseudo-pregnancy following an infertile mating. In the rabbit, coitus elicits reflex ovulation. In the sheep, cervical stimulation in the presence of high levels of estrogen can induce maternal behavior in a virgin ewe. These effects are all mediated by the hypothalamus, and the information is carried mainly by spinal pathways that relay in the brainstem. Stimulation of the nipples stimulates release of oxytocin and prolactin and suppresses the release of LH and FSH. Cardiovascular stimuli are carried by the vagus nerve, but the vagus also conveys a variety of visceral information, including for instance signals arising from gastric distension to suppress feeding. Again this information reaches the hypothalamus via relays in the brainstem. Nuclei The hypothalamic nuclei include the following:345 Hypothalamic nuclei Hypothalamic nuclei Region Area Nucleus Function6 Anterior Medial Medial preoptic nucleus urinary bladder contraction Decreased heart rate Decreased blood pressure Supraoptic nucleus SO oxytocin release vasopressin release Paraventricular nucleus PV oxytocin release vasopressin release7 Anterior hypothalamic nucleus AH thermoregulation panting sweating thyrotropin inhibition Suprachiasmatic nucleus SC vasopressin release Circadian rhythms Lateral Lateral preoptic nucleus Lateral nucleus LT thirst and hunger Part of supraoptic nucleus SO vasopressin release Tuberal Medial Dorsomedial hypothalamic nucleus DM GI stimulation Ventromedial nucleus VM satiety neurendocrine control Arcuate nucleus AR neurendocrine control Lateral Lateral nucleus LT thirst and hunger Lateral tuberal nuclei Posterior Medial Mammillary nuclei part of mammillary bodies MB feeding reflexes Posterior nucleus PN Increase blood pressure pupillary dilation shivering Lateral Lateral nucleus LT See also: ventrolateral preoptic nucleus Outputs The outputs of the hypothalamus can be divided into two categories: neural projections, and endocrine hormones.8 Neural projections Most fiber systems of the hypothalamus run in two ways bidirectional. Projections to areas caudal to the hypothalamus go through the medial forebrain bundle, the mammillotegmental tract and the dorsal longitudinal fasciculus. Projections to areas rostral to the hypothalamus are carried by the mammillothalamic tract, the fornix and terminal stria. Endocrine hormones The Hypothalamus affects the endocrine system and governs emotional behavior, such as, anger and sexual activity. Most of the hypothalamic hormones generated are distributed to the pituitary via the hypophyseal portal system.9 The hypothalamus maintains homeostasis this includes a regulation of blood pressure, heart rate, and temperature. The primary hypothalamic hormones are: Name Other Names Abbreviations Location Function Corticotropin-releasing hormone Corticotropin-releasing factor, Corticoliberin CRH, CRF parvocellular neuroendocrine neurons in the paraventricular nucleus with vasopressin, stimulates anterior pituitary to secrete ACTH Dopamine Prolactin-inhibiting hormone DA, PIH neuroendocrine neurons of the arcuate nucleus inhibits secretion of prolactin from the anterior pituitary Gonadotropin-releasing hormone Luteinising-hormone releasing hormone GnRH, LHRH neuroendocrine neurons in the medial preoptic and arcuate nuclei stimulates anterior pituitary to secrete LH and FSH Growth hormone-releasing hormone Growth-hormone-releasing factor, somatocrinin GHRH, GHRF, GRF arcuate nucleus neuroendocrine neurons stimulates anterior pituitary to secrete growth hormone Melatonin suprachiasmatic nucleus Somatostatin Growth hormone-inhibiting hormone, Somatotropin release-inhibiting factor SS, GHIH, SRIF neuroendocrine neurons of the periventricular nucleus inhibits secretion of growth hormone from the anterior pituitary Thyrotropin-releasing hormone Thyrotropin-releasing factor, Thyroliberin, Protirelin TRH, TRF parvocellular neuroendocrine neurons in the paraventricular and anterior hypothalamic nuclei stimulates anterior pituitary to secrete TSH See also: Hypocretin Control of food intake The extreme lateral part of the ventromedial nucleus of the hypothalamus is responsible for the control of food intake. Stimulation of this area causes increased food intake. Bilateral lesion of this area causes complete cessation of food intake. Medial parts of the nucleus have a controlling effect on the lateral part. Bilateral lesion of the medial part of the ventromedial nucleus causes hyperphagia and obesity of the animal. Further lesion of the lateral part of the ventromedial nucleus in the same animal produces complete cessation of food intake. There are different hypotheses related to this regulation:10 Lipostatic hypothesis - this hypothesis holds that adipose tissue produces a humoral signal that is proportionate to the amount of fat and acts on the hypothalamus to decrease food intake and increase energy output. It has been evident that a hormone leptin acts on the hypothalamus to decrease food intake and increase energy output. Gutpeptide hypothesis - gastrointestinal hormones like Grp, glucagons, CCK and others claimed to inhibit food intake. The food entering the gastrointestinal tract triggers the release of these hormones which acts on the brain to produce satiety. The brain contains both CCK-A and CCK-B receptors. Glucostatic hypothesis - the activity of the satiety center in the ventromedial nuclei is probably governed by the glucose utilization in the neurons. It has been postulated that when their glucose utilization is low and consequently when the arteriovenous blood glucose difference across them is low, the activity across the neurons decrease. Under these conditions, the activity of the feeding center is unchecked and the individual feels hungry. Food intake is rapidly increased by intraventricular administration of 2-deoxyglucose therefore decreasing glucose utilization in cells. Thermostatic hypothesis - according to this hypothesis, a decrease in body temperature below a given set point stimulates appetite, while an increase above the set point inhibits appetite. Sexual dimorphism Several hypothalamic nuclei are sexually dimorphic, i.e. there are clear differences in both structure and function between males and females. Some differences are apparent even in gross neuroanatomy: most notable is the sexually dimorphic nucleus within the preoptic area, which is present only in males. However most of the differences are subtle changes in the connectivity and chemical sensitivity of particular sets of neurons. The importance of these changes can be recognised by functional differences between males and females. For instance, the pattern of secretion of growth hormone is sexually dimorphic, and this is one reason why in many species, adult males are much larger than females. Responses to ovarian steroids Other striking functional dimorphisms are in the behavioral responses to ovarian steroids of the adult. Males and females respond differently to ovarian steroids, partly because the expression of estrogen-sensitive neurons in the hypothalamus is sexually dimorphic, i.e. estrogen receptors are expressed in different sets of neurons. Estrogen and progesterone can influence gene expression in particular neurons or induce changes in cell membrane potential and kinase activation, leading to diverse non-genomic cellular functions. Estrogen and progesterone bind to their cognate nuclear hormone receptors, which translocate to the cell nucleus and interact with regions of DNA known as Hormone response elements HREs or get tethered to another transcription factor's binding site. Estrogen receptor ER has been shown to transactivate other transcription factors in this manner, despite the absence of an estrogen response element ERE in the proximal promoter region of the gene. ERs and Progesterone receptors PRs are generally gene activators, with increased mRNA and subsequent protein synthesis following hormone exposure. Male and female brains differ in the distribution of estrogen receptors, and this difference is an irreversible consequence of neonatal steroid exposure. Estrogen receptors and progesterone receptors are found mainly in neurons in the anterior and mediobasal hypothalamus, notably: the preoptic area where LHRH neurons are located the periventricular nucleus where somatostatin neurons are located the ventromedial hypothalamus which is important for sexual behavior. Gonadal steroids in neonatal life of rats In neonatal life, gonadal steroids influence the development of the neuroendocrine hypothalamus. For instance, they determine the ability of females to exhibit a normal reproductive cycle, and of males and females to display appropriate reproductive behaviors in adult life. If a female rat is injected once with testosterone in the first few days of postnatal life during the critical period of sex-steroid influence, the hypothalamus is irreversibly masculinized; the adult rat will be incapable of generating an LH surge in response to estrogen a characteristic of females, but will be capable of exhibiting male sexual behaviors mounting a sexually receptive female. By contrast, a male rat castrated just after birth will be feminized, and the adult will show female sexual behavior in response to estrogen sexual receptivity, lordosis. Androgens in primates In primates, the developmental influence of androgens is less clear, and the consequences are less complete. 'Tomboyism' in girls might reflect the effects of androgens on the fetal brain, but the sex of rearing during the first 2-3 years is believed by many to be the most important determinant of gender identity, because during this phase either estrogen or testosterone will have permanent effects on either a female or male brain, influencing both heterosexuality and homosexuality.11 The paradox is that the masculinizing effects of testosterone are mediated by estrogen. Within the brain, testosterone is aromatized to estradiol, which is the principal active hormone for developmental influences. The human testis secretes high levels of testosterone from about week 8 of fetal life until 5-6 months after birth a similar perinatal surge in testosterone is observed in many species, a process that appears to underlie the male phenotype. Estrogen from the maternal circulation is relatively ineffective, partly because of the high circulating levels of steroid-binding proteins in pregnancy. Other influences upon hypothalamic development Sex steroids are not the only important influences upon hypothalamic development; in particular, pre-pubertal stress in early life determines the capacity of the adult hypothalamus to respond to an acute stressor.12 Unlike gonadal steroid receptors, glucocorticoid receptors are very widespread throughout the brain; in the paraventricular nucleus, they mediate negative feedback control of CRF synthesis and secretion, but elsewhere their role is not well understood. Effects of aging on the hypothalamus Studies in female mice have shown that both Supraoptic nucleus SON and Paraventricular nucleus PVN lose approximately one-third of IGF-1R immunoreactive cells with normal aging. Also, Old caloricly restricted CR mice lost higher numbers of IGF-1R non-immunoreactive cells while maintaining similar counts of IGF-1R immunoreactive cells in comparison to Old-Al mice. Consequently, Old-CR mice show a higher percentage of IGF-1R immunoreactive cells reflecting increased hypothalamic sensitivity to IGF-1 in comparison to normally aging mice. 13 14 15 See also Hypothalamic-pituitary-adrenal axis HPA axis Neuroendocrinology John Leonora Additional images Median sagittal section of brain of human embryo of three months. Human brain left dissected midsagittal view References ^ Definition of hypothalamus - NCI Dictionary of Cancer Terms ^ hypothalamus ^ Diagram of Nuclei psycheducation.org ^ Diagram of Nuclei universe-review.ca ^ Diagram of Nuclei utdallas.edu ^ Unless else specified in table, then ref is: Guyton Eight ion ^ Walter F., PhD. Boron. Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. ISBN 1-4160-2328-3. Page 840 ^ Hypothalamus and ANS ^ Overview of Hypothalamic and Pituitary Hormones ^ Theologides A 1976. Anorexia-producing intermediary metabolites. Am J Clin Nutr 29 5: 552-8. PMID 178168. ^ John Money, 'The concept of gender identity disorder in childhood and adolescence after 39 years', Journal of Sex and Marital Therapy 20 1994: 163-77. ^ Romeo, Russell D; Rudy Bellani, Ilia N. Karatsoreos, Nara Chhua, Mary Vernov, Cheryl D. Conrad and Bruce S. McEwen 2005. Stress History and Pubertal Development Interact to Shape Hypothalamic-Pituitary-Adrenal Axis Plasticity. Endocrinology 147 4: 1664-1674. The Endocrine Society. doi:10.1210/en.2005-1432. PMID 16410296. Retrieved on 2007-10-16. ^ Saeed O,Yaghmaie F,Garan SA,Gouw AM,Voelker MA,Sternberg H, Timiras PS. 2007. Insulin-like growth factor-1 receptor immunoreactive cells are selectively maintained in the paraventricular hypothalamus of calorically restricted mice. Int J Dev Neurosci 25 1: 23-8. doi:10.1016/j.ijdevneu.2006.11.004. PMID 17194562. ^ Yaghmaie F, Saeed O, Garan SA, Voelker MA, Gouw AM, Freitag W, Sternberg H, Timiras PS 2006. Age-dependent loss of insulin-like growth factor-1 receptor immunoreactive cells in the supraoptic hypothalamus is reduced in calorically restricted mice. Int J Dev Neurosci 24 7: 431-6. doi:10.1016/j.ijdevneu.2006.08.008. PMID 17034982. ^ F. Yaghmaie, O. Saeed, S.A. Garan, A.M. Gouw, P. Jafar, J. Kaur, S. Nijjar, P.S. Timiras, H. Sternberg, M.A. Voelker 2007. Tracking changes in hypothalamic IGF-1 sensitivity with aging and caloric restriction. Experimental Gerontology 42 1-2: 148-149. doi:10.1016/j.exger.2006.06.043. 1 External links BrainMaps at UCDavis Hypothalamus The Hypothalamus and Pituitary at endotexts.org v d e Brain: diencephalon Epithalamus Pineal body Habenula Habenular nuclei Stria medullaris Habenular trigone Habenular commissure Thalamus/nuclei paired: AN Ventral VA/VL, VP/VPM/VPL Lateral Pulvinar Metathalamus MG, LG midline: MD Intralaminar Centromedian Midline nuclear group Interthalamic adhesion Medullary laminae surface: reticular tracts to thalamus: Mammillothalamic tract Thalamic fasciculus Lenticular fasciculus Ansa lenticularis Medial lemniscus Trigeminal lemniscus Spinothalamic tract Lateral lemniscus Hypothalamus autonomic zones: Anterior parasympathetic/heat loss Posterior sympathetic/heat conservation endocrine - posterior pituitary: magnocellular/Paraventricular/Supraoptic oxytocin/vasopressin endocrine - other: parvocellular/Arcuate dopamine/GHRH Preoptic GnRH Suprachiasmatic melatonin emotion: Lateral hunger Ventromedial satiety Dorsomedial rage surface: Median eminence/Tuber cinereum Mammillary body Infundibulum tracts: Medial forebrain bundle Pituitary: Posterior is diencephalon, but anterior is glandular Subthalamus Subthalamic nucleus Zona incerta v d e Human anatomy, endocrine system: endocrine glands Hypothalamic/ pituitary axes Thyroid axis Thyroid gland Parafollicular cell, Thyroid epithelial cell, Thyroid isthmus, Lobes of thyroid gland, Pyramid of thyroid Parathyroid gland Oxyphil cell, Chief cell Adrenal axis Adrenal gland Gonadal axis Testes - Ovaries - Corpus luteum Pineal gland Pinealocyte Islets of pancreas Alpha cell - Beta cell - Delta cell - PP cell - Epsilon cell v d e Human brain: Limbic system Diencephalon Hypothalamus · Mammillary body Telencephalon: limbic lobe Archicortex: Hippocampal formation Hippocampus, Alveus of the hippocampus, Subiculum, Perforant path, Fimbria, Dentate gyrus · Paraterminal gyrus · Supracallosal gyrus Cingulate gyrus · Parahippocampal gyrus · Uncus Telencephalon: other Amygdala · Nucleus accumbens · Orbitofrontal cortex septum: Septum pellucidum, Septal nuclei Retrieved from http://en..org/wiki/Hypothalamus Categories: Limbic system | Endocrine system | Cerebrum | Neuroanatomy | Neuroendocrinology Views Article Discussion this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Go Search Interaction Community portal Recent changes Contact Donate to Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages العربية БългарÑ?ки Català Česky Dansk Deutsch Þ‹Þ¨ÞˆÞ¬Þ€Þ¨Þ„Þ¦Þ?Þ° Español Ù?ارسی Français Hrvatski Italiano עברית Latina Magyar Nederlands 日本語 ‪Norsk bokmÃ¥l‬ ‪Norsk nynorsk‬ Polski Português Română РуÑ?Ñ?кий Simple English SlovenÄ?ina Suomi Svenska ไทย Türkçe ä¸æ–‡ This page was last modified on 20 August 2008, at 13:30
39 Reasons to Drink Acai Juice Every Day
What is MonaVie - Watch the 8-minute video
Discovering MonaVie Video
The Power of You Video
Effects of MonaVie Active on Antioxidant Capacity in Humans
Log into your Wholesale MonaVie Account
So many of us do not eat a balanced diet, get enough sleep, have too much stress, or are impacted with toxins and pollutants. Drinking 2 ounces of MonaVie twice a day will help your body detoxify as well as build your immune system. Its the smartest thing you can do for yourself, so start today. Buying MonaVie through our company guarantees you support 7 days a week and, if you would like to share MonaVie with your family and friends we will guide you from start to finish.
1. Click on Enroll Now (30 - 55% off retail price)
2. Pay $39 for your Wholesale ID number.
3. NO minimum order required.
4. MonaVie is delivered to your door in 3 to 5 days.