The endocrine system in our body is made of several types of glands that secrete chemical messengers called hormones. These hormones circulate and transmit information from a group of cells to another, or between tissues and organs.
The most important glands that comprise the endocrine system include the thyroid, pituitary, the adrenals and the hypothalamus glands. The hypothalamus hormones directly control and regulate a wide variety of bodily processes.
What is Hypothalamus?
The hypothalamus is a tiny gland located towards the base of the brain and lies above the pituitary gland. The function of hypothalamus in the brain is a vital one; it forms a direct link between the endocrine system and the nervous system through the pituitary gland.
Location of Hypothalamus
The hypothalamus is a small organ located in the brain that controls secretions from the pituitary gland which sends hormones to different organs.
The brain is a mass of nervous tissue at the front end of an organism that functions as the “command and control system” of our body. The human brain is classified into three different main parts: the forebrain, the midbrain, and the hindbrain. The hypothalamus is part of the forebrain and is at the base of the thalamus bordered on the sides by temporal lobes and optic tracts. It includes many centers that control not only our body temperature, but also our daily activities.
Structure of Hypothalamus
The hypothalamus has a somewhat complex structure and comprises three regions. Each of these is made up of different kinds of nuclei. These nuclei are groups of nerve cells or neurons that carry out many important functions, such as secreting hormones.
The Parts of Hypothalamus are:
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Anterior region or Supraoptic region
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Middle region or Tuberal region
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Posterior region or Mammillary region
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Anterior Region
The anterior region is also known as the supraoptic region. The supraoptic part is made of the supraoptic and paraventricular nuclei. These nuclei mostly secrete hormones that interact with the pituitary gland to form more hormones.
The anterior region secretes some essential hypothalamus hormones. These are:
1. Vasopressin
Vasopressin is also known as the antidiuretic hormone or ADH. It modulates the levels of water in the body.
2. Oxytocin
The hormone oxytocin regulates several emotional responses and behaviour such as recognition, sexual arousal, excitement and trust. It also controls some parts of the reproductive system, such as lactation and childbirth.
3. Thyrotropin-releasing Hormone (TRH)
The TRH signals the pituitary gland to secrete thyroid-stimulating hormone or TSH.
4. Corticotropin-Releasing Hormone
The CRH stimulates the pituitary to secrete the adrenocorticotropic hormone or the ACTH. The ACTH signals the secretion of stress hormone which is known as cortisol.
5. Somatostatin
Somatostatin stops the pituitary gland from secreting some specific hormones.
6. Gonadotropin-Releasing Hormone (GnRH)
GnRH causes the pituitary to secrete reproductive hormones like FSH and LH.
The anterior region also helps maintain the body’s circadian rhythms and body temperature.
Now, let us recapitulate a few concepts with the following exercise.
Pop Quiz 1
1. Where is the Hypothalamus Located?
a. base of the brain and below pituitary gland
b. top of the brain and above pituitary gland
c. base of the brain and above pituitary gland
d. top of the brain and below pituitary gland
Middle Region
Also known as the tuberal region, this middle region of the hypothalamus is mostly made up of the ventromedial and arcuate nuclei. The ventromedial nucleus helps to regulate appetite, and the arcuate plays a role in secreting GHRH or the growth hormone-releasing hormone. It is responsible for the proper growth and development of a body.
Posterior Region
Known as the mammillary region, the posterior region consists of the posterior hypothalamic nucleus and the mammillary nucleus. It helps control and stabilize body temperature and is also believed to play a role in memory and cognition.
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Now we know all about the structure of this hypothalamus. Let us revise our concepts with the following quiz.
Pop Quiz 2
1. Which of these are Hormones Secreted by Hypothalamus?
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Oxytocin
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Thyrotropin-releasing hormone (TRH)
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Corticotropin-releasing hormone
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All of these above
Functions of Hypothalamus
The hypothalamus connects to various parts of the central nervous system. It is connected to the brainstem, the part of the brain that carries information from the peripheral nerves and spinal cord to the upper part of the brain. The brainstem contains parts of the midbrain and hindbrain. The hypothalamus is also connected to the peripheral nervous system. With these connections, the hypothalamus can affect many autonomic or involuntary functions.
Besides the hypothalamus hormones, the hypothalamus also features osmotic sensors that react to concentrations of chloride, carbon dioxide, potassium and sodium. These osmotic sensors signal the kidneys to store or release water depending on their respective levels. The role of hypothalamus is an essential one and includes these following activities:
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Maintaining sleep cycles
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Connects the nervous and endocrine systems
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Balances body fluids
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Regulates blood pressure and heart rate
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Autonomic function control
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Maintains homeostasis, such as regulating body temperature, appetite and body weight, heart rate and blood pressure, etc.
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Motor function check
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Eating and Drinking
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Emotion control
Disorders of Hypothalamus
Besides these, the hypothalamus secretes hormones that are involved in many other functions such as appetite and thirst control. Optimum levels of hormones in the bloodstream are necessary for the body to function properly. Low or high levels of a particular hormone could lead to hypothalamus disorders. These include:
It is important to eat a balanced diet and ensure that the hypothalamus is healthy and functional.
For more on the work of hypothalamus and other glands in the endocrine system, refer to our PDF notes and solved question papers. Install the app today and discover an exciting world of learning with easy access to study materials and online interactive sessions.