Hypothalamus – Anatomy
The hypothalamus is a part of the diencephalon. It lies on the floor and lateral wall of the third ventricle. It has been designated as the head ganglion of the autonomic nervous system because it takes part in the control of many visceral and metabolic activities of the body.
Parts of the Hypothalamus
The hypothalamus is subdivided into optic tuberal and mammillary parts. The nuclei present in each part are as follows.
Supraoptic nucleus, above the optic chiasma.
Paraventricular nucleus just above the supraoptic nucleus.
Tuberal nucleus, lateral to the ventromedial nucleus.
Posterior nucleus caudal to the ventromedial and dorsomedial nuclei.
Lateral nucleus lateral to the posterior nucleus.
The nuclei 3, 4 and 6 are separated from nuclei 5 and 7 by the column of the fornix, the mammillothalamic tract and the fasciculus retro flexus.
Afferents: The hypothalamus receives visceral sensations through the spinal cord and brainstem. It is also connected to several centers associated with olfactory pathways, including the piriform cortex; with the cerebellum; and with the retina.
Supraopticohypophyseal track from the optic nuclei to the pars posterior, the pars tuberalis and the pars intermedia of the hypophysis cerebral.
Functions of Hypothalamus
Endocrine Control: By forming releasing hormones or release inhibiting hormones, the hypothalamus regulates secretion of thyrotropin (TSH) corticotropin (ACTH), SOMATOTROPIN (STH) prolactin, luteinizing hormone (LH) follicle stimulating hormone (FSH) and melanocyte-stimulating hormone by pars anterior of the hypophysis cerebral.
Neurosecretion: Oxytocin and vasopressin are secreted by the hypothalamus and transported to the infundibulum.
General Autonomic Effect: The anterior parts of the hypothalamus chiefly mediate parasympathetic activity, and the posterior parts chiefly mediate sympathetic activity.
Temperature Regulation: The hypothalamus maintains a balance between heat production and heat loss of the body.
Regulation of Foot and Water Intake: The hunger or feeding center is placed laterally the satiety center causes hyperphagia leading to obesity
Sexual Behaviour and Reproduction: Through its control of the anterior pituitary the hypothalamus controls gametogenesis various reproductive cycles and the maturation and maintenance of secondary sexual characteristics.
Emotion, Fear, Rage, Aversion, Pleasure and Rewards: These faculties are controlled by the hypothalamus the limbic system and the prefrontal cortex.
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