region of the brain that plays an important role in maintaining homeostasis, sexual behavior, mood and other important body functions. Although humans is less than 1% of the total volume of the brain, the hypothalamus exerts important effects on the endocrine system (whose bodies produce and secrete hormones), the autonomic nervous system (which controls involuntary actions) and limbic system, part of the nervous system that acts on the little-known behavior.
The human hypothalamus, che pesa circa 5 g, fa parte del diencefalo. È situato intorno e sopra il pavimento del terzo ventricolo, inferiormente al talamo e superiormente all’ ipofisi , alla quale è attaccato dal peduncolo ipofisario. L’ipotalamo è diviso in vari nuclei (aggregati di corpi di cellule nervose) e collegato con fibre nervose a tutte le altre parti del cervello. Riceve segnali nervosi dalle zone erogene (i genitali e i capezzoli), dai visceri (organi interni) e dal sistema limbico. Inoltre può rilevare cambiamenti dell’osmolarità del sangue ed è influenzato dalla concentrazione sanguigna degli ormoni . In questo modo, l’ipotalamo integra segnali fisici ed emotivi provenienti da tutto il body and initiates the appropriate responses.
The hypothalamus has vascular connections with the anterior pituitary (hypothalamic-pituitary portal system), and nerve connections that connect to the posterior lobe of the gland itself. These connections shall run along the pituitary stalk.
Some nerve fibers are connected to hypothalamic neuronal groups of spinal cord, and are linked to homeostatic functions, such as thermoregulation, regulation of hunger and thirst, the trend of heart rate and the degree of constriction of blood vessels.
The human hypothalamus, che pesa circa 5 g, fa parte del diencefalo. È situato intorno e sopra il pavimento del terzo ventricolo, inferiormente al talamo e superiormente all’ ipofisi , alla quale è attaccato dal peduncolo ipofisario. L’ipotalamo è diviso in vari nuclei (aggregati di corpi di cellule nervose) e collegato con fibre nervose a tutte le altre parti del cervello. Riceve segnali nervosi dalle zone erogene (i genitali e i capezzoli), dai visceri (organi interni) e dal sistema limbico. Inoltre può rilevare cambiamenti dell’osmolarità del sangue ed è influenzato dalla concentrazione sanguigna degli ormoni . In questo modo, l’ipotalamo integra segnali fisici ed emotivi provenienti da tutto il body and initiates the appropriate responses.
The hypothalamus has vascular connections with the anterior pituitary (hypothalamic-pituitary portal system), and nerve connections that connect to the posterior lobe of the gland itself. These connections shall run along the pituitary stalk.
Some nerve fibers are connected to hypothalamic neuronal groups of spinal cord, and are linked to homeostatic functions, such as thermoregulation, regulation of hunger and thirst, the trend of heart rate and the degree of constriction of blood vessels.
Experiments in rats have clearly demonstrated that the hypothalamus plays an important role in the regulation of feeding behavior: if the hypothalamus is damaged in the middle region, the rat eats too much and become obese, and if, instead, the ventral part is damaged, the rat refuses to eat and starving. In humans, however, the hypothalamus plays a less important role than in rodents, because food intake is that human activity is also affected by other influences. In this respect was, for example, demonstrated that the customs and habits have a greater influence on the amount of food eaten than the feeling of hunger, hence could, however, derive the high incidence of obesity in civilization characterized by high levels of well-being.
The hypothalamus also influences on the cardiovascular and the autonomic nervous system involved in the integration of the actions of the body with the mind. The hypothalamus is, for example, responsible for physical changes to be made to make an effort.
In the hypothalamus has also established a kind of thermostat that controls the body temperature (thermoregulation ), causing the contraction or dilation of peripheral blood vessels.
The hypothalamus also influences on the cardiovascular and the autonomic nervous system involved in the integration of the actions of the body with the mind. The hypothalamus is, for example, responsible for physical changes to be made to make an effort.
In the hypothalamus has also established a kind of thermostat that controls the body temperature (thermoregulation ), causing the contraction or dilation of peripheral blood vessels.
The hypothalamus is responsible for the control of hormones released by the anterior and posterior lobes of ' pituitary. The substances secreted by this brain region are properly and neurohormones are called factors: 1) the release of corticotropin-factor (CRF) stimulates the secretion of corticotropin or adrenocorticotropic hormone (ACTH), 2) the factor of liberation thyrotropin (TRF) induces the synthesis of hormone or thyrotropin (TSH), 3) the release of growth hormone (GHRH) and somatostatin, respectively, stimulate and inhibit the production of growth hormone (GH ) 4) the factor for the Liberation of gonadotropin (GnRH) controls the secretion of follicle stimulating hormone (FSH) and the luteinizing hormone (LH), 5) the factor inhibiting the release of prolactin and prolactin release factor regulating the production of prolactin.
sovraottico and paraventricular nuclei of the hypothalamus synthesize oxytocin and vasopressin (or antidiuretic hormone). These two compounds are transported along fiber axons in the posterior lobe of the pituitary, and are deposited in granules, in response to nervous stimuli, are freed and released into the bloodstream. In addition to adopting hormone, vasopressin and oxytocin can act by neurotransmitters. It has been shown that these hormones are responsible for the transmission of nerve impulses between the hypothalamus and the limbic system and spinal cord.
Oxytocin is involved in the secretion of milk and, to a lesser extent, the stimulation of childbirth. The act of sucking the infant stimulates a pathway that connects the nipple to the hypothalamus and causes the release of oxytocin, which, in turn, stimolala secretion of milk for the baby. The same effect can be caused by tears in the mother of the baby: this is an example of links with other parts of the hypothalamus of the brain. The vasopressin is involved in controlling the water content of the body and acts on the distal nephron, the distal convoluted tubule and collecting duct of the kidney , which increases the reabsorption of water from the glomerular filtration rate, thus maintaining a constant level of water in the body.
A part of the hypothalamus, the suprachiasmatic nucleus, is involved in regulating circadian rhythms body, fluctuations in blood levels of certain hormones that occur during a period of 24 hours and, in general, related to periods of light and darkness. This ensures that the blood concentration of certain hormones from reaching the valore richiesto nel momento di maggiore bisogno del corpo. Ad esempio, il livello del cortisolo aumenta abitualmente al mattino prima del risveglio, provocando l’innalzamento della glicemia e controbilanciando gli effetti, altrimenti deleteri, della mancata alimentazione durante il sonno notturno.
sovraottico and paraventricular nuclei of the hypothalamus synthesize oxytocin and vasopressin (or antidiuretic hormone). These two compounds are transported along fiber axons in the posterior lobe of the pituitary, and are deposited in granules, in response to nervous stimuli, are freed and released into the bloodstream. In addition to adopting hormone, vasopressin and oxytocin can act by neurotransmitters. It has been shown that these hormones are responsible for the transmission of nerve impulses between the hypothalamus and the limbic system and spinal cord.
Oxytocin is involved in the secretion of milk and, to a lesser extent, the stimulation of childbirth. The act of sucking the infant stimulates a pathway that connects the nipple to the hypothalamus and causes the release of oxytocin, which, in turn, stimolala secretion of milk for the baby. The same effect can be caused by tears in the mother of the baby: this is an example of links with other parts of the hypothalamus of the brain. The vasopressin is involved in controlling the water content of the body and acts on the distal nephron, the distal convoluted tubule and collecting duct of the kidney , which increases the reabsorption of water from the glomerular filtration rate, thus maintaining a constant level of water in the body.
A part of the hypothalamus, the suprachiasmatic nucleus, is involved in regulating circadian rhythms body, fluctuations in blood levels of certain hormones that occur during a period of 24 hours and, in general, related to periods of light and darkness. This ensures that the blood concentration of certain hormones from reaching the valore richiesto nel momento di maggiore bisogno del corpo. Ad esempio, il livello del cortisolo aumenta abitualmente al mattino prima del risveglio, provocando l’innalzamento della glicemia e controbilanciando gli effetti, altrimenti deleteri, della mancata alimentazione durante il sonno notturno.
L’ipotalamo può presentare lesioni in seguito a un intervento chirurgico, a un trauma , come un incidente stradale o un ictus, alla degenerazione per vecchiaia o a una malattia o un tumore. Le conseguenze del danno possono essere molto diverse e dipendono dalla zona colpita.
Il diabete insipido può essere provocato da una lesione ipotalamica o da un danno al tratto ipotalamico-ipofisario. Ciò riduce il livello di produzione della vasopressina e determina la produzione di volumi elevati di urina .
Altre manifestazioni di danni ipotalamici possono essere anomalie sessuali (come la pubertà precoce), disturbi psichici , obesità , anoressia , problemi di termoregolazione, disturbi del sonno e alterazione dei normali ritmi circadiani.
Il diabete insipido può essere provocato da una lesione ipotalamica o da un danno al tratto ipotalamico-ipofisario. Ciò riduce il livello di produzione della vasopressina e determina la produzione di volumi elevati di urina .
Altre manifestazioni di danni ipotalamici possono essere anomalie sessuali (come la pubertà precoce), disturbi psichici , obesità , anoressia , problemi di termoregolazione, disturbi del sonno e alterazione dei normali ritmi circadiani.
fonte: encarta MSN
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