Hypothalamus: Function, Conditions, Disorders, Treatment

What Is the Hypothalamus?

The hypothalamus is the small portion of the brain located right under the thalamus and above the pituitary gland and forms the floor and walls of the third ventricle. It acts as the core centre for regulating most of the basic functions of the body, such as temperature control, hunger, thirst, sleep, and emotion.

The hypothalamus is indispensable to homeostasis; it provides a clear link between the nervous and endocrine systems through its actions on the pituitary, which then acts on other endocrine glands scattered in the body. Through the integration of signals originating from other parts of the brain and body, there are coordinated and balanced physiological responses to changes occurring both inside and outside the body.

Anatomy of the Hypothalamus

Hypothalamus is an essential structure of the brain comprising several anatomically separate nuclei and regions, each associated with specific functions.

Structural Regions

It has anatomically been divided into three main regions:

Anterior region

• Lies at the front part of the hypothalamus and includes the supraoptic nucleus and paraventricular nucleus.

• Concerned with the regulation of temperature, thirst, and secretions of antidiuretic hormone and oxytocin from the posterior pituitary.

Middle Region

• Core region in the hypothalamus includes several nuclei, like the ventromedial nucleus and the arcuate nucleus.

• Related to the control of hunger and satiety,

• Regulates the majority of hormones, notably those controlling growth and reproduction.

Posteriors Region

• Located at the back of the hypothalamus.

• Contains nuclei such as the mammillary bodies and posterior nucleus.

• Operates in the field of regulation of body temperature and actions of the sympathetic nervous system.

Functions of the Hypothalamus

The hypothalamus plays an important role in maintaining the state of internal balance of the body, or homeostasis, through several major functions:

Temperature Control

It senses the temperature conditions of the body and drives mechanisms to achieve thermal homeostasis either by sweating or by shivering.

Hunger and Thirst

It regulates hunger and thirst by responding to messages about the body's energy and fluid needs.

Sleep-Wake Cycle

The hypothalamus produces circadian rhythms by acting on sleep and wakefulness and follows cycles of day and night.

Emotional Responses

It regulates emotions. Through the autonomic nervous system, it acts on premises formed by limbic structures that are concerned with emotional expression.

Endocrine System Interaction

The various releasing and inhibiting hormones that act on the anterior pituitary are produced and secreted by it and regulate its secretion of a host of hormones.

Through the pituitary, it controls the secretion of hormones that govern growth, metabolism, response to stress as well as reproductive functions.

Hypothalamic Hormones

Most of these physiological functions are mediated by the release of specific hormones from the hypothalamus itself.

Types of Hormones

The types of hormones are:

Major Hormones and Functions

The major hormones are:

Thyrotropin-releasing hormone (TRH)

• The TRH stimulates the anterior pituitary to release Thyroid-Stimulating Hormone (TSH), which in turn, stimulates the thyroid gland to produce thyroid hormones (T3 and T4).

• These hormones are very essential in regulating metabolism processes, growth, and development.

Gonadotropin-releasing hormone (GnRH)

• GnRH triggers the anterior pituitary to secrete Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH).

• This will then trigger the reproductive hormones, which are in charge of the reproductive cycle, such as the menstrual cycle in females and spermatogenesis in males.

Growth Hormone-releasing Hormone (GHRH)

• GHRH will trigger the anterior pituitary to release GH, a hormone necessary for the growth of the body's tissues, cellular repairs, and metabolism.

Corticotropin-releasing Hormone (CRH)

• This stimulates the anterior pituitary to produce Adrenocorticotropic Hormone (ACTH).

• The latter will, in turn, signal to have the adrenal glands to produce cortisol.

• It is involved in the response against stress, metabolism, and regulation of inflammation.

Hypothalamic Disorders

Appropriate amounts of each hormone should be released. Hypothalamic problems can result from secretions that are either extremely high or extremely low.

Causes

The following issues may be the cause of hypothalamic disorders:

• Head injuries

• Genetic illnesses

• Hypothalamic tumours

• Eating disorders

• Brain Surgeries

• Autoimmune diseases

Symptoms

The following signs point to a hypothalamic disorder:

• Variations in body temperature

• Infertility

• Abnormal blood pressure

• Sleeplessness

• Appetite changes

• Excess urination

• Delayed puberty

All things considered, the hypothalamus is a tiny area in the middle of the brain that is crucial in telling the pituitary gland to release hormones to the rest of the entire endocrine system.

Hypothalamus NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Hypothalamic hormones and their functions

• Anatomy of Hypothalamus

Practice Questions for NEET

Q1. Hormones produced by Hypothalamus

1. Regulate synthesis of pituitary hormones

2. Regulate secretion of pituitary hormones

3. Regulate secretion of adrenal gland

4. More than one correct answer

Correct answer: 4) More than one correct answer

Explanation:

Hormones produced by Hypothalamus - These hormones regulate the synthesis and secretion of pituitary hormones. The hypothalamus produces releasing hormones (e.g., GnRH, TRH, CRH) and inhibiting hormones (e.g., somatostatin, dopamine) that regulate the anterior pituitary's function. It also synthesizes oxytocin and vasopressin (ADH), which are stored and released by the posterior pituitary. These hormones play critical roles in maintaining homeostasis, stress response, and reproductive processes.

Hence, the correct answer is option 4) More than one correct answer.

Q2. The hypothalamus is the basal part of

1. Forebrain

2. Diencephalon

3. Limbic system

4. More than one correct answer.

Correct answer: 4) More than one correct answer.

Explanation:

The hypothalamus is a significant component of the forebrain, situated within the diencephalon, a distinct region of the forebrain. The hypothalamus is a vital component of the diencephalon. It is essential for homeostasis regulation, controlling various bodily functions such as temperature, appetite, thirst, sleep, and hormone management. It acts as a bridge between the nervous and endocrine systems, using the pituitary gland to modulate growth, metabolism, and stress-related activities.

Hence, the correct answer is option 4) More than one correct answer.

Q3. LH and FSH are collectively called

1. Somatotrophins

2. Oxytocin

3. Gonadotrophins

4. Luteotropic hormones

Correct answer: 3) Gonadotrophins

Explanation:

LH and FSH are the main gonadotropins secreted by the anterior pituitary gland, and they are triggered by the action of GnRH from the hypothalamus. These hormones control gonadal function: LH is responsible for androgen production by Leydig cells in the testes and for progesterone in the ovaries, and FSH causes spermatogenesis in Sertoli cells of the testes and estrogen secretion in ovarian follicles. Therefore, both hormones are necessary for proper reproductive function.

Hence the correct answer is option (3) gonadotrophins.

Also Read:

• MCQs on Hypothalamus

• Mechanism of Hormone Action

• Pancreas Function in Human Body

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