How do hormones like ADH affect water balance?

ADH, or antidiuretic hormone, helps regulate water balance by controlling the amount of water reabsorbed by the kidneys.

ADH, also known as vasopressin, is a hormone produced in the hypothalamus and stored in the pituitary gland at the base of the brain. It plays a crucial role in maintaining the body's water balance. When the body is dehydrated, the concentration of solutes in the blood increases. This change is detected by osmoreceptors in the hypothalamus, which then stimulate the release of ADH.

Once released, ADH travels in the bloodstream to the kidneys. Here, it acts on the cells of the collecting ducts, making them more permeable to water. This means that more water is reabsorbed back into the bloodstream, rather than being excreted as urine. As a result, the volume of urine produced decreases, and its concentration increases. This process helps to conserve water and restore the solute concentration in the blood to normal levels.

Conversely, when the body is well-hydrated, less ADH is released. This makes the collecting ducts in the kidneys less permeable to water, leading to more water being excreted in the urine. This helps to prevent water overload and maintain the correct balance of water in the body.

In summary, ADH plays a vital role in regulating the body's water balance. It does this by adjusting the amount of water reabsorbed by the kidneys, in response to changes in the body's hydration levels. This ensures that the body always has the right amount of water to function properly.