Hypothalamus

What is Hypothalamus?

Hypothalamus is a minute region, almost the size of an almond, present at the centre of the brain, near the pituitary gland.

It consists of three main regions:

  • the anterior region,

  • the middle region,

  • the posterior region.

It plays a vital role in the production of hormones. Maintaining the hypothalamus health is very important. Its improper functioning causes several disorders.

Structure of Hypothalamus

The structure of hypothalamus is made up of three main regions:

  • Anterior region

  • Middle region

  • Posterior region

Anterior Region

The anterior region is also known as the supraoptic region.

It regulates body temperature and maintains the circadian rhythm.

There are several small nuclei in the hypothalamus. The major nuclei include supraoptic and paraventricular nuclei.

The nuclei in this region are involved in the hormone secretion. Following are the hormones secreted by the anterior region of the hypothalamus:

  • Corticotropin-releasing hormone

  • Thyrotropin-releasing hormone

  • Gonadotropin-releasing hormone

  • Oxytocin

  • Vasopressin

  • Somatostatin

Middle Region

This is known as the tuberal region. It consists of ventromedial and arcuate nuclei.

The ventromedial nuclei control the appetite, whereas the arcuate nuclei secrete the growth hormone responsible for the growth and development of the body.

Posterior Region

This region is also known as the mammillary region. The major nuclei include posterior hypothalamic nucleus and mammillary nuclei.

The posterior hypothalamic nuclei cause shivering and blockage of sweat and thus regulates the body temperature. The mammillary nuclei, on the contrary, are believed to be involved in the memory function.

Hypothalamus Functions

Following are the important hypothalamus functions:

  • Its main function is maintaining the body’s internal balance- homeostasis. Hypothalamus stimulates or inhibits many of the body’s activities in order to maintain homeostasis, such as regulating body temperature, appetite and body weight, heart rate and blood pressure, etc.

  • It also connects the endocrine and the nervous system.

  • It is involved in many essential functions of the body.

  • Regulating body temperature

  • Appetite and thirst control

  • Childbirth

  • Sleep cycles

  • Emotions

  • Blood pressure and heart rate

  • Balancing body fluids

Hormones secreted by Hypothalamus

The anterior region of the hypothalamus is responsible for hormone secretion. The nuclei present in this region lead the process. The important hormones secreted by hypothalamus are:

  1. Anti-diuretic Hormone: It increases the amount of water absorbed in the blood by the kidneys. It is also known as vasopressin.

  2. Corticotropin-Releasing Hormone: This hormone is responsible for the regulation of metabolic and immune response.

  3. Thyrotropin Releasing Hormone: It triggers the pituitary gland to release thyroid stimulating hormone which plays a major role in the functioning of organs of the body such as heart, muscles, etc.

  4. Gonadotropin Releasing Hormone: It stimulates the pituitary gland to release several reproductive hormones.

  5. Oxytocin: It is involved in several processes such as lactation, childbirth, regulating sleep cycles, maintaining body temperature.

  6. Somatostatin: This hormone is also known as Growth Hormone Inhibiting Hormone. It regulates the endocrine system and affects the neurotransmission and cell proliferation by interacting with G-protein coupled receptors.

The middle region of hypothalamus stimulates the release of Growth Hormone Releasing Hormone. This hormone plays a major role in the growth and development of the body.

Hypothalamic Disorders

Every hormone should be secreted at accurate levels. Very high or very low secretions can lead to hypothalamic disorders. Hypothalamic disorders can be due to the following problems:

  • Head injuries

  • Genetic disorders

  • Tumours in the hypothalamus

  • Disorders in eating

  • Brain surgeries

  • Autoimmune disorders

The symptoms that indicate a hypothalamic disorder include:

  • Body temperature fluctuations

  • Infertility

  • Unusually high or low blood pressure

  • Insomnia

  • Change in appetite

  • Frequent urination

  • Delayed puberty

The hypothalamus plays a major role in signalling the pituitary gland to release hormones to the rest of the endocrine system.

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