hypothalamus

hypothalamus /hy·po·thal·a·mus/ (-thal´ah-mus) the part of the diencephalon forming the floor and part of the lateral wall of the third ventricle, including the optic chiasm, mammillary bodies, tuber cinereum, and infundibulum; the pituitary gland is also in this region but is physiologically distinct. Hypothalamic nuclei help activate, control, and integrate peripheral autonomic mechanisms, endocrine activities, and many somatic functions.hypothalam´ic

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hy·po·thal·a·mus (hp-thl-ms)

n.

The part of the brain that lies below the thalamus, forming the major portion of the ventral region of the diencephalon, and that regulates bodily temperature, certain metabolic processes, and other autonomic activities.

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hypo·tha·lamic (-th-lmk) adj.

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Hypothalamus

A structure within the brain responsible for a large number of normal functions throughout the body, including regulating sleep, temperature, eating, and sexual development. The hypothalamus also regulates the functions of the pituitary gland by directing the pituitary to stop or start production of its hormones.

Mentioned in: Acromegaly and Gigantism, Anxiety, Cushing's Syndrome, Follicle-Stimulating Hormone Test, Hypogonadism, Hypothyroidism, Narcolepsy, Puberty, Stress Reduction

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hypothalamus

[hī′pōthal′əməs]

Etymology: Gk, hypo + thalamos, chamber

a portion of the diencephalon of the brain, forming the floor and part of the lateral wall of the third ventricle. It activates, controls, and integrates the peripheral autonomic nervous system, endocrine processes, and many somatic functions, such as body temperature, sleep, and appetite. Compare epithalamus, metathalamus, subthalamus, thalamus. hypothalamic, adj.

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hypothalamus (hī´pōthal´mus),

n a small extension of the brain that lies in the sella turcica in the cranium. It lies just at the superior level of the body of the sphenoid bone. It is intimately related structurally and functionally with the pituitary gland and is important in the central regulation of the endocrine glands, including the thyroid gland, pancreas, adrenal glands, and gonads. The most important visceral functions are under control of the hypothalamus because it functions in such close coordination with the endocrine glands. The control is mediated through its structural communication with the pituitary gland.

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hypothalamus

the portion of the diencephalon lying beneath the thalamus at the base of the cerebrum, and forming the floor and part of the lateral wall of the third ventricle. It includes the optic chiasm, mammillary bodies, tuber cinereum, infundibulum and hypophysis (pituitary gland), but for physiological purposes, the hypophysis is considered a distinct structure.

The hypothalamic nuclei activate, control and integrate many of the involuntary functions necessary for living. The various hypothalamic centers influence peripheral autonomic mechanisms, endocrine activity and many somatic functions, e.g. a general regulation of water balance, body temperature, sleep, thirst and hunger, and the development of secondary sex characteristics.

Because of its influence on the release and inhibition of pituitary hormones, the hypothalamus indirectly plays an important role in the regulation of protein, fat and carbohydrate metabolism, body fluid volume and electrolyte content, and internal secretion of endocrine hormones. The hormones synthesized and secreted by the special neurons of the hypothalamus are called hypothalamic releasing and inhibiting hormones or factors. They act directly on the tissues of the pituitary gland. Some of the major hypothalamic factors are: thyroid-stimulating hormone releasing hormone (TRH), which activates the release of the thyroid-stimulating hormone (TSH) from the anterior lobe of the pituitary gland; corticotropin-releasing factor (CRF); growth hormone releasing factor (GHRF); gonadotropin releasing hormone (GnRH); and prolactin-inhibiting factor (PIF). In addition, there are other stimulating and inhibiting factors that influence the release and retention of other anterior pituitary hormones.

The hypothalamic hormones or factors are secreted directly into the veins in the lower part of the hypothalamus and are transported directly to the tissues of the pituitary gland. This transportation network is called the hypothalamic-hypophyseal portal system. The secretion of the hypothalamic hormones is a part of a regulatory negative feedback system that continuously operates to maintain homeostasis.

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hypothalamus

A group of nuclei at the base of the brain located in the floor of the third ventricle. It consists of the optic chiasma, the paired mammillary bodies, the tuber cinereum, the infundibulum and the pars posterior of the pituitary gland.