subject: Hypothalamus Function [print this page] Introduction to hypothalamus Introduction to hypothalamus
Hypothalamus is the area of the brain which forms the floor and part of the lateral wall of the third ventricle.It is composed of many nuclei scattered in this area.Hypothalamus being the key region for maintenance of homeostasis forms a very important part of CNS.It is intimately involved in regulation of many vital functions and is also related to endocrine regulation.It not only acts as head ganglion of ANS but also ensures coordination between autonomic and somatic responses as in emotional expressions. .
Functions of Hypothalamus
Autonomic Function:Hypothalamus is intimately related to ANS .When the anterior hypothalamus is stimulated,various changes are seen in parasympathetic stimulation like contraction of urinary bladder,vasodilatation ,fall in blood pressure etc.Stimulation of posterior and lateral parts of hypothalamus produce changes in sympathetic stimulation like vasoconstriction,rise of blood pressure and heart rate.
Sleep:Hypothalamus is involved in sleep-awake mechanism.Sleep awake cycle is altered after stimulation of hypothalamus.
Circadian rhythm:Circadian rhythm,as seen in different functions of the body relating 24 hours light and dark cycle,is an important function brought about by hypothalamus.
Feeding and satiety:The feeding centre is located in lateral hypothalamus ,which when stimulated leads to food intake(if available).The satiety centre when stimulated inhibits the feeding centre.
Thirst mechanism:Another important function of Hypothalamus is regulation of thirst mechanism.The thirst centre in hypothalamus receives information about water deficit in the body and initiates water intake to correct the deficit.
Temperature regulation:Hypothalamus contains the thermostat which helps to maintain body temperature at a constant level.This thermostat receives information about internal and external temperature and initiates the mechanism to lose or gain heat and maintain the body temperature within a narrow range like in case of human beings.
Regulation of emotional behaviour:Hypothalamus being intimately connected to the limbic system,plays important role in rage ,fight and other emotional behaviour.
Regulation of various vital functions like cardiovascular,respiratory system etc have contribution from hypothalamus.
Hypothalamus Function in Endocrine Regulation
Hypothalamus and pituitary function as a single unit due to their structural and functional relationship.The anterior pituitary is connected to hypothalamus through hypothalamo-hypophyseal portal circulation.This allows hormones of hypothalamus to reach pituitary (their target area).The hormones secreted by hypothalamus and their function are as follows.
1 Growth hormone releasing hormone(GNRH) leads to 'rArr' release of Growth hormone(GH).
2 Thyrotropin releasing hormone (TRH) leads to 'rArr' release of Thyroid stimulating hormone(TSH) and Prolactin(PRL).
3 Corticotropin releasing hormone(CRH) leads to 'rArr' release of ACTH.
4 Gonadotropin releasing hormone (GnRH) leads to 'rArr' release of LH and FSH.
5 Somatostatin leads to 'rArr' inhibition of GH and TSH.
