Hypothalamus is a tiny part of our brain and it directs a number of important functions in the body. Since it produces hormones, these hormones govern body temperature, hunger, sleep, sex drive, moods, thirst and the release of other hormones in the body. It is responsible for most of our physiological, emotional and behavioural responses.

Ironical to such a big name and so many functions, Hypothalamus is of the size of an almond and it weighs even lesser than 1 percent of the weight of brain..This small organ located in the human brain has numerous fibre tracts and nuclei.

The nuclei of the Hypothalamus are divided into three different divisions:

• Anterior (or chiasmatic)

• Median (or tuberal)

• Posterior (or mammillary)

This division is based on the hypothalamic blood supply of the brain to the respective regions. The anterior Hypothalamus gets its blood supply from the anterior cerebral and anterior communicating arteries. The posterior communicating arteries supply blood to the median Hypothalamus and the posterior Hypothalamus has its blood supplier as the posterior communicating artery, posterior cerebral and basilar arteries.

Hypothalamus plays a vital role for our living. It plays the role of a mediator between the nervous system and the endocrine system.
The major functions of Hypothalamus are:

• It releases eight hormones which in turn control the release of eight hormones by the pituitary gland

• It also controls and regulates our body temperature

• It is also responsible for the hunger, thirst and our intake of foods and water

• Reproduction and sexual behaviours are also controlled by Hypothalamus

• It also regulates daily physiological states and behaviours

• The emotional responses are also mediated by Hypothalamus

The eight hormones secreted by Hypothalamus are anti-diuretic hormone, oxytocin, corticotropin-releasing hormone, dopamine, growth hormone-releasing hormone, somatostatin, gonadotropin-releasing hormone and thyrotropin-releasing hormone.

Anti-diuretic hormone reabsorbs water in the kidneys reducing the urine volume and also prevents dehydration. Oxytocin stimulates uterine contraction during childbirth and also the flow of breast milk while breastfeeding. Gonadotropin-releasing hormone regulates the production of gonads-controlling hormones. Thyrotropin-releasing hormone regulates the thyroid gland by promoting the secretion of its functional hormones. Corticotropin-releasing hormone controls the adrenal cortex, growth hormone-releasing hormone regulates the production of growth hormones, dopamine acts as a neurotransmitter that sends out signals to other nerve cells and somatostatin inhibits the growth hormones and the thyroid-stimulating hormones.

Certain conditions such as head trauma, brain tumours, infection, surgery, radiation and malnutrition might hamper the functions of the Hypothalamus leading to certain disorders.

The major disorder caused by improper functioning of Hypothalamus is diabetes insipidus. It is when the kidney fails to reabsorb water leading to excessive loss of dilute urine which is caused due to the lack of anti-diuretic hormone. Some of the other disorders are insomnia, loss of energy balance and thermoregulation.

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