Category Archives: Hypothalamus

Hidden in your hypothalamus, you have a satiety center that regulates your appetite. It's controlled by two counter-balancing chemicals that are located side-by-side. - The satiety chemicals led by CART (the C stands for cocaine and A for amphetamine, since these drugs put this chemical into overdrive). CART stimulates the surrounding hypothalamus to increase metabolism, reduce appetite, and increase insulin to deliver energy to cells rather than be stored as fat. - The eating chemicals driven by NPY (a protein called neuropeptide Y). NPY has the opposite effect on the hypothalamusdecreasing metabolism and increasing appetite. It fires off those signals for you to eat, eat, eat. The biological message: Prevent starvation by eating. Think of the two substancesNPY and CARTas villain and angel. Both are competing for the same parking space, the one that will ultimately determine whether or not you eat. They both arrive at the same time and want that space. Either more NPY or CART sneak into the place, thus sending the all-important go or stop signal to your brain to influence the hormones that make you feel full or hungry. How do we know these centers work this way? In animal models, we see that if … Continue reading →

At the core of any well-oiled machine, there is a busy engine that keeps it going. The hypothalamus is at the center of a plethora of physiological processes including, but not limited to, thermoregulation, osmoregulation and hormonal regulation. It also works closely with the pituitary gland to modulate endocrine activity based on the bodys physiological demands. The purpose of this article will be to evaluate the gross anatomical organization and vascular supply of the hypothalamus. Additionally, the article will look at key anatomical relationships to other structures, some associated neuronal pathways and the function of different nuclei of hupothalamus. The human hypothalamus and its nuclei Recommended video: Medial view of the brain Structures seen on the medial view of the brain. The images show a midsagittal section of the brain. The left and right lateral walls of the third ventricle are divided by an anteroposterior depression known as the hypothalamic sulcus. It runs from the anterior tip of the fornix between the interventricular foramen of Monro superiorly and the anterior commissure inferiorly to the posterior commissure (superior to the beginning of the cerebral aqueduct of Sylvius). This depression separates the thalamus (superiorly) from the hypothalamus (inferiorly). Anterior (preoptic) hypothalamic area … Continue reading →

The hypothalamus is a portion of the brain near the third ventricle, located below the thalamus and above the brainstem. The anterior boundary of the hypothalamus is determined by the line connecting the anterior commissure, the lamina terminalis and the optic chiasm. The lower limit of the hypothalamus is formed by the infundibulum, the tuber cinerum and the mamillary bodies. The posterior limit is represented by a straight line joining the mamillary bodies and the posterior commissure. The hypothalamus is involved in the following control systems: body temperature autonomic nervous system emotional and food behavior endocrine (via the pituitary) circadian rhythm. MRI of the Brain (hypothalamus): T1-weighted sagittal cut. Image 1. 1, Anterior commissure. 2, Corpus callosum. 3, Third ventricle. 4, Cerebellum. 5, Pons. 6, Pituitary gland. MRI of the Brain (hypothalamus): T1-weighted sagittal cut. Image 1. 1, Anterior commissure. 2, Corpus callosum. 3, Third ventricle. 4, Cerebellum. 5, Pons. 6, Pituitary gland. MRI of the Brain (hypothalamus): T1-weighted axial cut. Image 2. 1, Anterior commissure. 2, Putamen. 3, Third ventricle. 4, Corpus callosum. MRI of the Brain (hypothalamus): T1-weighted coronal cut. Image 3. 1, Anterior commissure. 2, Caudate nucleus. 3, Corpus callosum. 4, Lateral ventricle. 5, Third ventricle. MRI … Continue reading →

Last Updated On April 29, 2013 By surekha Hypothalamus, though small in size, directs and controls range of functions of the body. It is located beneath the thalamus region and is bordered on its side by temporal lobes. It is that portion of the brain that is responsible for controlling homeostasis (internal balance of the body). It is the center that controls many autonomic functions of the body. It maintains strong connections with endocrine and nervous systems. Hypothalamus is the region that produces many hormones. Hypothalamus is the part that either stimulates or inhibits bodys vital functions like heart rate and blood pressure. It controls and determines body temperature. This portion of the brain is responsible for causing thirst and maintains electrolyte balance in your body. It controls the glandular secretions of intestine and stomach. It regulates your sleep cycle. It is responsible for controlling motor functions of the body. Hormones Secreted by Hypothalamus : Hypothalamus is vital in maintaining the functions of pituitary gland in the brain. Once it receives signal from the nervous system, it secretes neuro-hormones which in turn initiates the secretion of several pituitary hormones like Anti Diuretic hormone ADH, Corticotropin Releasing Hormone CRH, Gonadotrophin Releasing … Continue reading →

The hypothalamus helps regulate a number of important behavioral and physiological functions such as body temperature, eating and drinking habits, emotional well-being and sleep, according to the National Institute of General Medical Sciences. Normally, your brains hypothalamus releases GnRH, which stimulates your pituitary gland to let loose some FSH and LH. Many can interfere with the activity of the hypothalamus, a part of the brain that helps regulate temperature and thirst. This produces a stress response in your bodyspecifically, your brains hypothalamus triggers your sympathetic nervous system to release norepinephrine (aka adrenaline) and cortisol (a stress hormone) to get you out of harms way. Studies in both animals and humans showed that CGRP and its receptors are found in brain structures such as the hypothalamus and cerebellum, which were long thought to play a role in generating migraine attacks. Daily circadian rhythm is controlled by a collection of neurons in an area of the brain called the hypothalamus. The hypothalamus may continue to secrete hormones, for example. Essentially, the brains hypothalamus produces gonadotropin-releasing hormone, which causes the pituitary gland to produce FSH and LH. Link: Hypothalamus | Definition of Hypothalamus by Merriam-Webster … Continue reading →

The hypothalamus is a small area at the base of the brain, weighing about 4 gm out of the 1400 gm brain weight of an adult human, yet it performs a wide range of functions that are vital for the survival of the individual. In general, the hypothalamus acts as a integrator to regulate and coordinate basic functions necessary for life, such as fluid and electrolyte balance; feeding and energy metabolism; wake-sleep cycles; thermoregulation; stress responses; and sexual behavior and reproduction. Located just behind and between the eyes, the anterior border of the hypothalamus is formed by the optic chiasm. It is bordered laterally by the optic tracts and temporal lobes, and the posterior limit of the hypothalamus, occupied by the mammillary bodies, is bounded by the cerebral peduncles. The hypothalamus, literally located below the thalamus, is divided in the midline by the third ventricle. It contains a series of reasonably well differentiated cell groups or nuclei, sandwiched between to major axonal pathways that connect it with the rest of the brain and with the endocrine system. The periventricular axon system occupies the medial wall of the hypothalamus along the third ventricle, medial to most of the hypothalamic nuclei. It … Continue reading →

Hypothalamic disease is a disorder presenting primarily in the hypothalamus, which may be caused by damage resulting from malnutrition, including anorexia and bulimia eating disorders,[1][2] genetic disorders, radiation, surgery, head trauma,[3] lesion,[1] tumour or other physical injury to the hypothalamus. The hypothalamus is the control center for several endocrine functions. Endocrine systems controlled by the hypothalamus are regulated by anti-diuretic hormone (ADH), corticotropin-releasing hormone, gonadotropin-releasing hormone, growth hormone-releasing hormone, oxytocin, all of which are secreted by the hypothalamus. Damage to the hypothalamus may impact any of these hormones and the related endocrine systems. Many of these hypothalamic hormones act on the pituitary gland. Hypothalamic disease therefore affects the functioning of the pituitary and the target organs controlled by the pituitary, including the adrenal glands, ovaries and testes, and the thyroid gland.[2] Numerous dysfunctions manifest as a result of hypothalamic disease. Damage to the hypothalamus may cause disruptions in body temperature regulation, growth, weight, sodium and water balance, milk production, emotions, and sleep cycles.[1][2][4] Hypopituitarism, neurogenic diabetes insipidus, tertiary hypothyroidism, and developmental disorders are examples of precipitating conditions caused by hypothalamic disease. The hypothalamus and pituitary gland are tightly integrated. Damage to the hypothalamus will impact the responsiveness and normal functioning … Continue reading →

The paraventricular nucleus (PVN, PVA, or PVH) is a nucleus in the hypothalamus.[1] It is a group of neurons that can be activated by physiological changes including stress. Many PVN neurons project directly to the posterior pituitary where they release oxytocin into the general circulation. While the supraoptic nucleus releases vasopressin. Both the PVN and the supraoptic nucleus do produce small amounts of the other hormone, ADH and Oxytocin respectively. Other PVN neurons control various anterior pituitary functions, while still others directly regulate appetite and autonomic functions in the brainstem and spinal cord. The paraventricular nucleus lies adjacent to the third ventricle. It lies within the periventricular zone and is not to be confused with the periventricular nucleus, which occupies a more medial position, beneath the third ventricle. The PVN is highly vascularised and is protected by the bloodbrain barrier, although its neuroendocrine cells extend to sites (in the median eminence and in the posterior pituitary) beyond the bloodbrain barrier. The PVN contains magnocellular neurosecretory cells whose axons extend into the posterior pituitary, parvocellular neurosecretory (neuroendocrine) cells that project to the median eminence, and several populations of peptide-containing cells that project to many different brain regions including parvocellular preautonomic cells … Continue reading →

The lateral hypothalamus, also called the lateral hypothalamic area,[1] contains the primary orexinergic nucleus within the hypothalamus that widely projects throughout the nervous system;[2] this system of neurons mediates an array of cognitive and physical processes, such as promoting feeding behavior and arousal, reducing pain perception, and regulating body temperature, digestive functions, and blood pressure, among many others.[2][3][4] Clinically significant disorders that involve dysfunctions of the orexinergic projection system include narcolepsy, motility disorders or functional gastrointestinal disorders involving visceral hypersensitivity (e.g., irritable bowel syndrome),[3][5] and eating disorders.[6] The neurotransmitter glutamate and the endocannabinoids (e.g., anandamide) and the orexin neuropeptides orexin-A and orexin-B are the primary signaling neurochemicals in orexin neurons;[3][4][7] pathway-specific neurochemicals include GABA, melanin-concentrating hormone, nociceptin, glucose, the dynorphin peptides, and the appetite-regulating peptide hormones leptin and ghrelin, among others.[3][8] Notably, cannabinoid receptor 1 (CB1) is colocalized on orexinergic projection neurons in the lateral hypothalamus and many output structures,[4][7] where the CB1 and orexin receptor 1 (OX1) receptors form the CB1OX1 receptor heterodimer.[4][9][10] The orexinergic projections from the lateral hypothalamus innervate the entirety of the remainder of the hypothalamus, with robust projections to the posterior hypothalamus, tuberomammillary nucleus (the histamine projection nucleus), the arcuate nucleus, and the paraventricular hypothalamic … Continue reading →

The ventromedial nucleus of the hypothalamus (VMN, also sometimes referred to as the ventromedial hypothalamus, VMH) is a nucleus of the hypothalamus. "The ventromedial hypothalamus (VMH) is a distinct morphological nucleus involved in terminating hunger, fear, thermoregulation, and sexual activity."[1] This nuclear region is involved with the recognition of the feeling of fullness. It has four subdivisions: These subdivisions differ anatomically, neurochemically, and behaviorally. The ventromedial nucleus (VMN) is most commonly associated with satiety. Early studies showed that VMN lesions caused over-eating and obesity in rats. However, the interpretation of these experiments was summarily discredited when Gold's research demonstrated that precision lesioning of the VMN did not result in hyperphagia.[2] Nevertheless, numerous studies have shown that the immediacy of hyperphagia and obesity syndrome are a consequence of VMN lesions or procaine injections, and point to the VMN's role in satiety.[3][4][5][6][7][8][9] A major review of the subject in 2006 concluded that, "anatomical studies done both before and after Gold's study did not replicate his results with lesions, and in nearly every published direct comparison of VMH lesions vs. PVN or VNAB lesions, the group with VMH lesions ate substantially more food and gained twice as much weight."[10] This strongly substantiates the … Continue reading →