hypothalamus

(hī'pəthăl`əməs), an important supervisory center in the brainbrain,
the supervisory center of the nervous system in all vertebrates. It also serves as the site of emotions, memory, self-awareness, and thought. Anatomy and Function
..... Click the link for more information. , rich in ganglia, nerve fibers, and synaptic connections. It is composed of several sections called nuclei, each of which controls a specific function. The hypothalamus regulates body temperature, blood pressure, heartbeat, metabolism of fats and carbohydrates, and sugar levels in the blood. Through direct attachment to the pituitary glandpituitary gland,
small oval endocrine gland that lies at the base of the brain. It is sometimes called the master gland of the body because all the other endocrine glands depend on its secretions for stimulation (see endocrine system).
..... Click the link for more information. , the hypothalamus also meters secretions controlling water balance and milk production in the female. The role of the hypothalamus in awareness of pleasure and pain has been well established in the laboratory. It is thought to be involved in the expression of emotions, such as fear and rage, and in sexual behaviors. Despite its numerous vital functions, the hypothalamus in humans accounts for only 1-300 of total brain weight, and is about the size of an almond. Structurally, it is joined to the thalamusthalamus
, mass of nerve cells centrally located in the brain just below the cerebrum and resembling a large egg in size and shape. The thalamus is a routing station for all incoming sensory impulses except those of smell, transmitting them to higher (cerebral) nerve centers.
..... Click the link for more information. ; the two work together to monitor the sleep-wake cycle.

Hypothalamus

a part of the brain under the thalamus opticus.

The hypothalamus is part of the diencephalon, forming the walls and floor of the third ventricle; the pituitary body, or hypophysis, is suspended from it on a thin stalk. The hypothalamus is an aggregate of higher adaptive centers that integrate and adjust functions to the body’s coordinated activity, playing a major role in maintaining the metabolic level and in regulating the activity of the digestive, cardiovascular, endocrine, and other physiological systems. Thus, the hypothalamus is one of the most important members of a functional system that coordinates autonomic with psychic and somatic functions. It contains more than 30 paired clusters of nerve cells, called nuclei, and it is connected by a large number of neural pathways to the upper and lower divisions of the central nervous system. Certain hormones (for example, vasopressin) and a variety of biologically active substances are formed in the nerve cells of the hypothalamic nuclei. These active substances (the so-called releasing factors) enter the hypophysis by way of the blood vessels and nerve fibers and promote the secretion of hormones.

The hypothalamus exerts neurohumoral and hormonal control over the functions and regulates the activity of the endocrine glands according to the needs of the cells, organs, physiological systems, and the body as a whole. The hypothalamus is furnished with a rich network of blood vessels and receptors that sense the slightest changes in temperature and sugar, salt, water, and hormone content in the internal environment. Fluctuations in the composition and properties of the internal environment trigger corresponding mechanisms that organize feeding and sexual behavior and create the conditions necessary for the maintenance of constant body temperature. Structures that form part of a complex system regulating the alternation and maintenance of sleep and wakefulness are also present in the hypothalamus. The posterior portions of the hypothalamus consist largely of structures that, mostly with the help of the peripheral sym-patheticoadrenal apparatus, provide autonomic and endocrine support for physical and mental activity and adaptation of the body to changes in the external and internal environments (the so-called ergotropic state). The anterior portions of the hypothalamus regulate chiefly the restorative and assimilative processes (the so-called trophotropic state) and maintain the relative constancy of the body’s internal environment (homeostasis). Injury to the hypothalamus results in endocrine, metabolic, trophic, or autonomic disorders, including changes in thermoregulation, sleep and wakefulness, and emotion.

REFERENCES

Fiziologiia i patologiia dientsefal’noi oblasti golovnogo mozga. Moscow, 1963. (Collection of articles.)
Grashchenkov, N. I. Gipotalamus: ego rol’ v fiziologii i patologii. Moscow, 1964.
Fiziologiia i patofiziologiia gipotalamusa. Moscow, 1966.
Monnier, M. Functions of the Nervous System, vol. 1. Amsterdam, 1968.

A. M. VEIN

hypothalamus

[¦hī·pō′thal·ə·məs] (neuroscience) The floor of the third brain ventricle; site of production of several substances that act on the adenohypophysis.

Hypothalamus

hy·po·thal·a·mus

(hī'pō-thal'ă-mŭs), [TA] The ventral and medial regions of the diencephalon forming the walls of approximately the ventral half of the third ventricle; it is delineated from the thalamus by the hypothalamic sulcus, lying medial to the internal capsule and subthalamus, continuous with the precommissural septum anteriorly and with the mesencephalic tegmentum and central gray substance posteriorly. Its ventral surface is marked by (from rostral to caudal) the optic chiasma, the unpaired infundibulum that extends by way of the infundibular stalk into the posterior lobe of the hypophysis, and the paired mammillary bodies. The hypothalamus consists of the anterior hypothalamic area [TA], dorsal hypothalamic area [TA], intermediate hypothalamic area [TA], lateral hypothalamic area [TA], and posterior hypothalamic area [TA], each of these containing specific nuclei. It has afferent fiber connections with the mesencephalon, limbic system, cerebellum, and efferent fiber connections with the same structures and with the posterior lobe of the hypophysis; its functional connection with the anterior lobe of the hypophysis is established by the hypothalamohypophysial portal system. The hypothalamus is prominently involved in the functions of the autonomic (visceral motor) nervous system and, through its vascular link with the anterior lobe of the hypophysis, in endocrine mechanisms; it also appears to play a role in neural mechanisms underlying moods and motivational states.
See also: pituitary gland. [hypo- + thalamus]

hypothalamus

(hī′pō-thăl′ə-məs)n. The part of the brain that lies below the thalamus, forming the major portion of the ventral region of the diencephalon and functioning to regulate bodily temperature, certain metabolic processes, and other autonomic activities.

hy′po·tha·lam′ic (-thə-lăm′ĭk) adj.

hy·po·thal·a·mus

(hī'pō-thal'ă-mŭs) [TA] The ventral and medial region of the diencephalon forming the walls of the ventral half of the third ventricle; delineated from the thalamus by the hypothalamic sulcus, lying medial to the internal capsule and subthalamus, continuous with the precommissural septum anteriorly and with the mesencephalic tegmentum and central gray substance posteriorly. Its ventral surface is marked by, from before backward, the optic chiasma, the unpaired infundibulum, which extends by way of the infundibular stalk into the posterior lobe of the hypophysis, and the paired mammillary bodies. The nerve cells of the hypothalamus are grouped into the supraoptic paraventricular, lateral preoptic, lateral hypothalamic, tuberal, anterior hypothalamic, ventromedial, dorsomedial, arcuate, posterior hypothalamic, and premammillary nuclei and into the mammillary body. It has afferent fiber connections with the mesencephalon, limbic system, cerebellum, and efferent fiber connections with the same structures and with the posterior lobe of the hypophysis; its functional connection with the anterior lobe of the hypophysis is established by the hypothalamohypophysial portal system. The hypothalamus is prominently involved in the functions of the autonomic nervous system and, through its vascular link with the anterior lobe of the hypophysis, in endocrine mechanisms; it also appears to play a role in neural mechanisms underlying moods and motivational states.
See also: hypophysis

hypothalamus

The region of the under-surface of the brain immediately above the pituitary gland. The hypothalamus is the area in which the nervous and hormonal systems of the body interact. It receives information relating to hormone levels, physical and mental stress, the emotions and the need for physical activity, and responds by prompting the pituitary appropriately. Nuclei in the lower region of the hypothalamus contain neurons that secrete growth hormone releasing hormone, gonadotropin releasing hormone, somatostatin and other regulating substances.

hypothalamus

the part of the sides and floor of the brain derived from the forebrain. Associated with the control of body temperature, it also partially controls the PITUITARY GLAND and contains centres controlling sleep and wakefulness, feeding, drinking, speech and osmoregulation, the last by secretion of ADH from neurosecretory cells. It is also associated with aspects of reproductive behaviour.

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

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.

hy·po·thal·a·mus

(hī'pō-thal'ă-mŭs) [TA] Ventral and medial regions of diencephalon forming walls of approximately the ventral half of third ventricle; delineated from the thalamus by the hypothalamic sulcus, lying medial to the internal capsule and subthalamus, continuous with the precommissural septum anteriorly and with the mesencephalic tegmentum and central gray substance posteriorly. [hypo- + thalamus]

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Words related to hypothalamus

noun a basal part of the diencephalon governing autonomic nervous system

Related Words