Antidiuretic Hormone (ADH)

Antidiuretic hormone (ADH), also known as vasopressin, is a hormone produced by the hypothalamus and released by the pituitary gland. Its primary function is to regulate the body's water balance by controlling the amount of water reabsorbed by the kidneys and the concentration of urine produced.

Function of ADH

ADH acts on the kidneys to increase the reabsorption of water, which helps to conserve body fluids and prevent dehydration. It does this by making the walls of the collecting ducts and distal convoluted tubules of the kidneys more permeable to water, allowing more water to be reabsorbed back into the bloodstream. As a result, the urine produced becomes more concentrated, helping to conserve water in the body.

Regulation of ADH

The release of ADH is tightly regulated by the body's internal water balance. When the body senses a decrease in blood volume or an increase in blood osmolarity (concentration of solutes), the hypothalamus signals the pituitary gland to release ADH. This triggers the kidneys to reabsorb more water, reducing the amount of urine produced and helping to maintain proper fluid balance in the body.

Disorders Related to ADH

Imbalances in ADH levels can lead to various disorders. For example, insufficient production or release of ADH can result in diabetes insipidus, a condition characterized by excessive urination and thirst. On the other hand, excessive ADH secretion can lead to syndrome of inappropriate antidiuretic hormone (SIADH), causing the body to retain too much water and leading to low sodium levels in the blood.

Study Guide

1. What is the primary function of ADH?
2. How does ADH affect the kidneys?
3. What triggers the release of ADH?
4. What are the consequences of insufficient ADH production?
5. What disorder is associated with excessive ADH secretion?