Antidiuretic Hormone (ADH)

Antidiuretic hormone (ADH), also known as vasopressin, is an important hormone produced by the hypothalamus and released by the posterior pituitary gland. It maintains water balance by increasing water reabsorption in the kidneys. ADH plays a great role in homeostasis, controlling blood volume and osmotic pressure. It is one of the major scoring chapters in biology in CBSE class 11. It accounts for 2-4% of total marks in entrance exams such as NEET, AIIMS, nursing, paramedical, and pharmacy.

Synthesis and Storage of Antidiuretic Hormone

Although the posterior pituitary lobe, or neurohypophysis, does not synthesize hormones, it does store and secrete two peptide hormones, namely oxytocin and vasopressin.

Antidiuretic Hormone is one of the two neurohormones synthesized by the neurosecretory cells present in the hypothalamus and carried to the neurohypophysis along the nerve fibres, where it is stored along with oxytocin.

Specialized neurons of the hypothalamus with the ability to secrete known as “neurosecretory cells,” synthesize these hormones, which are then transported axonally via neurohypophysial capillaries to the posterior lobe.

Thus, the antidiuretic hormone (ADH or vasopressin hormone) is secreted into the bloodstream by the posterior lobe of the pituitary gland present at the base of the brain.

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Factors Affecting the Regulation of Antidiuretic Hormone

The release of Antidiuretic Hormone into the bloodstream is regulated by various factors. These include:

Antidiuretic Hormone Functions

Some of the major functions of Antidiuretic Hormone is discussed below:

• The antidiuretic hormone causes vasoconstriction and clot formation.

• The antidiuretic hormone plays a significant role in regulating the biological clock.

• ADH maintains the body's homeostasis, blood volume & the smooth and proper flow of urine from the kidneys.

• Apart from this adh also maintains an appropriate volume of water in the spaces surrounding the cells inside the body.

• The antidiuretic hormone also aids in smooth cellular functions.

Mechanism of Action Antidiuretic Hormone

The Antidiuretic Hormone mechanism of action can be explained as follows-

Antidiuretic Hormone exerts an antidiuretic action by enhancing the reabsorption of water from the kidneys back into circulation. Antidiuretic or vasopressin affects V1 and V2 receptors to produce its effects.

Functions of Antidiuretic Hormones

ADH causes constriction of blood vessels and raises blood volume or blood pressure, which is why it is called vasopressin.

Side Effects Of Antidiuretic Hormones

Excess secretion of Antidiuretic Hormone can also lead to some major side effects in the body. Some of them are mentioned below:

• A low level of ADH in the blood results in diabetes insipidus, where the reabsorption of water is reduced.

• This results in excessive water loss through dilute urine.

• Antidiuretic hormone often lowers blood pressure and increases urine volume.

• Hyposecretion of adh also causes damage to the hypothalamus and pituitary gland.

• A high adh level causes the blood to dilute and the plasma to be low in sodium.

• Hypersecretion of adh can result in acute conditions with symptoms such as nausea, headache, dehydration, vomiting, etc.

Antidiuretic Hormonal Disorders

A hyper or hypo secretion of ADH often results in several disorders.

These are as follows-

• Insomnia

• Head injuries

• Infertility - Causes and Types of Solutions

• Delayed puberty

• Frequent urination

• Autoimmune disorders

• Change in appetite etc.

Tips, Tricks, And Strategies To Prepare For ADH Hormone

Here are some quick tips, tricks, and strategies to remember the role of ADH (antidiuretic hormone) or vasopressin:

"Anti-diuretic" = Less Uretic

• "Anti" means opposing, so ADH reduces urination by retaining water in the body.

Vasopressin = Vessel Pressure

• Vasopressin is another name for ADH. It presses the blood vessels, leading to an increase in blood pressure.

• Remember: Vasopressin = Vessel pressure rises.

V2 = Water Reabsorption

• V2 receptors in the kidneys help in water reabsorption.

• Tip: Think of H2O to remember V2's role with water.

V2 = Very Thirsty

• When ADH acts on the kidneys, water is reabsorbed, reducing thirst and maintaining hydration.

Types of Questions Asked on Antidiuretic Hormone in Different Exams

During preparation for different exams, students may face different questions on the topic of antidiuretic hormone

Weightage of Antidiuretic Hormone in Different Entrance Exams

The table which is given below contains the overall weightage of the topic of antidiuretic hormone in different exams. This will help in increasing concentration on the topic as per the weightage.

Conclusion

As we have gone through the details of antidiuretic hormone, its action, its regulatory pathway, and clinical significance it becomes important for us to understand why it is important for our body.

It is essential to recognize the implications for our health homeostasis and also the various physiological effects of ADH on our body. This is one of the underrated integrated relationships between our hormones and overall health.

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