Hypothalamus: Functions, Anatomy, and Disorders

What is Hypothalamus? Is it found in the human body? Hypothalamus is a part of our brain. This small region of our brain controls our body temperature and the release of hormones. The hypothalamus (from Ancient Greek ὑπό, “under”, and θάλαμoς, “chamber”) is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the hypothalamus’ most essential jobs is to connect the neurological and endocrine systems via the pituitary gland.

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Hypothalamus Definition

The hypothalamus is a small organ situated in the brain below the thalamus that controls the secretion of the pituitary gland.

The brain is the mass of nerve tissue in the anterior end of an organism and acts as the ‘command and control system’ of our body. The brain can be divided into three major parts, namely, forebrain, midbrain, and hindbrain. Hypothalamus is a part of the forebrain and lies at the base of the thalamus. It contains a number of centres that control our body temperature (homeostasis), activities regarding eating and drinking. It also regulates the functioning of the pituitary gland.

Hypothalamus Anatomy

The hypothalamus has three main regions. Each region contains different nuclei. These are clusters of neurons that perform important functions, like releasing hormones. 

Fig: An Image Showing the Hypothalamus in the Brain

Anterior Region

1. The anterior region is also known as the supraoptic region. Its major nuclei include the two types, namely, periventricular and supraoptic nuclei. 
2. The anterior region of the hypothalamus also helps in regulating body temperature through the process called sweating.
3. The nuclei in the anterior region are highly involved in the secretion of various hormones. Some of the important hormones are given below:
   (i) Gonadotropin-releasing hormone (GnRH) – GnRH production causes the pituitary gland to produce important reproductive hormones, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
   (ii) Corticotropin-releasing hormone (CRH) – This hormone plays a role in the body’s response to both emotional and physical stress. It signals the pituitary gland to produce a special hormone called adrenocorticotropic hormone (ACTH), and this ACTH triggers the production of cortisol which is an important stress hormone.
   (iii) Thyrotropin-releasing hormone (TRH) – TRH production by the hypothalamus stimulates the pituitary gland which in turn produces thyroid-stimulating hormone (TSH).
   (iv) Oxytocin – This hormone controls many important behaviours and emotions, such as sexual arousal, trust, recognition, and maternal behaviour, which also involves childbirth and lactation.
   (v) Vasopressin –  It is also known as the antidiuretic hormone (ADH) that is produced by the hypothalamus and stored in the posterior pituitary. It helps in regulating the water level in the body and vasopressin is regulated by arginine vasopressin (AVP) gene expression which is managed by major clock-controlled genes.
   (vi) Somatostatin – Somatostatin also acts as a neurotransmitter in the nervous system that works to stop the pituitary gland from releasing certain hormones, including growth hormones and thyroid-stimulating hormones. In the pancreas, somatostatin inhibits the secretion of pancreatic hormones, including insulin and glucagon.

Middle Region

1. This region is also known as the tuberal region. 
2. The major nuclei of the middle region are the ventromedial and arcuate nuclei. 
3. This regulates the growth and development of the body.

Posterior Region

1. The posterior region is also named the mammillary region. 
2. Its main nuclei include the posterior hypothalamic nucleus and mammillary nuclei.
3. The posterior hypothalamic nucleus helps regulate body temperature. 

Hypothalamus Functions

The functions of the Hypothalamus are listed below:

1. The hypothalamus helps in controlling and integrating the activities of the autonomic nervous system (ANS) which regulates the smooth and cardiac muscles and also the glands.
2. It helps in thermoregulation, i.e., it allows the maintenance of the body’s temperature within normal ranges. 
3. The hypothalamus regulates the intake of food through the ventromedial, dorsomedial, paraventricular and lateral hypothalamus nucleus.
4. It helps in the regulation of the body’s water content through the antidiuretic hormone secretion. 
5. The hypothalamus regulates the daily pattern of sleep.
6. It regulates the secretion of the hormones in the body through the releasing and inhibitory factors, and these hormones are involved in the process of growth, reproduction process and metabolism.

Hypothalamus Disorders

A hypothalamic disease is any disorder that prevents the hypothalamus from functioning properly. Some of them are given below:

1. Excessive dietary iron in the diet can also trigger hypothalamus disorders.
2. When the body is deprived of essential nutrients, it can interfere with the normal functioning of the hypothalamus. Hence, poor nutrition or malnutrition can certainly put a person in the risk zone of hypothalamus disorders.
3. Even an accident such as head injuries that affects the head can also lead to hypothalamus dysfunctions.
4. Some hypothalamic diseases have a genetic link or history. For example, Kallman syndrome causes hypothalamic problems in children. The most noticeable symptoms are delayed or absence of puberty accompanied by an impaired sense of smell.
5. Also, Prader-Willi Syndrome is a condition in which a missing chromosome leads to short stature and hypothalamic dysfunctions.
6. Excessive bleeding may also lead to hypothalamus disorders.

Hypothalamus and Pituitary Gland

Both Hypothalamus and Pituitary glands are the primary endocrine glands of the human body. Hypothalamus is a small area of the brain, which is a part of the forebrain, and the pituitary gland is located just below the hypothalamus. The pituitary gland comprises two lobes namely the anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis). 
The hypothalamus is connected to the anterior lobe of the pituitary gland with the help of a special portal blood system. The hypothalamus is directly connected to the posterior lobe of the pituitary gland of our body with the help of nerve cells or neurons.
Hence, the hypothalamus and pituitary gland are interconnected, and the hypothalamus is known to regulate the function of the pituitary gland.

Fig: An image Showing Hypothalamus and Pituitary gland

Summary

Despite its small size, the hypothalamus represents an important integrative part of the brain with complex functions. Without the hypothalamus, the posterior pituitary gland is not functional because all the hormones released from this gland are synthesized by specific neurons of the hypothalamus.

Apart from regulating the function of the pituitary gland, the hypothalamus plays an important role in thermoregulation, regulating sleep patterns, and many more. So, in a nutshell, it can be said that without the hypothalamus, the normal functioning of the body cannot take place as the function of many associated organs, glands and other body parts will be hampered in this case. 

Frequently Asked Questions

Here are some of the FAQs on the Hypothalamus:

Q.1. What is the main function of the hypothalamus?
Ans: The main function of the hypothalamus is to maintain the homeostasis of the body.

Q.2. Can the hypothalamus be reset?
Ans: Yes, the hypothalamus can be reset. Chance HRT (Hypothalamic Reset Technique) is a simple technique to reset the Hypothalamus. The Hypothalamus is called the “Brain of the Brain.” This technique allows the Hypothalamus to regain control over so many functions of our body.

Q.3. What are the 2 functions of the hypothalamus?
Ans: The two functions of the hypothalamus are:
a. It secretes hormones such as oxytocin, Thyrotropin-releasing hormone (TRH), etc.
b. It regulates the intake of food and also regulates the daily pattern of sleep.

Q.4. How does the hypothalamus affect behaviour?
Ans: The hypothalamus mainly produces hormones that regulate the emotional behaviour of the body—some hormones of the hypothalamus, involved in the reproduction process, childbirth, and lactation.

Q.5. What emotions does the hypothalamus control?
Ans: The hypothalamus is involved in emotions such as pleasure, while the median part is associated with displeasure and a tendency to uncontrollable and loud laughing.

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