What is the Difference Between ADH and Aldosterone?

ADH (antidiuretic hormone) and aldosterone are two hormones that play crucial roles in regulating blood pressure and fluid balance in the body. They have different target sites, mechanisms, and release factors:

1. Target Sites: ADH primarily acts on the collecting ducts to increase their permeability to water, enabling more water reabsorption. In contrast, aldosterone acts on the distal convoluted tubules and collecting ducts to promote sodium reabsorption, which subsequently causes passive water reabsorption through osmosis.
2. Mechanisms: ADH causes the reabsorption of just water, while aldosterone causes the reabsorption of water as well as sodium. ADH works by increasing the permeability of the collecting ducts to water, leading to the production of concentrated urine and an increase in blood volume and blood pressure. Aldosterone, on the other hand, promotes sodium reabsorption, which in turn causes water to follow due to osmosis, increasing blood volume and blood pressure.
3. Release Factors: ADH release is primarily stimulated by low blood pressure, low blood volume, or high blood osmolality, which can be sensed by osmoreceptors in the hypothalamus. Aldosterone release is primarily stimulated by low blood pressure, low blood volume, or low blood sodium levels.
4. Where They are Produced: ADH is a peptide hormone made in the brain and released by the posterior pituitary gland. Aldosterone is a corticosteroid hormone made in the adrenal glands.

In summary, both ADH and aldosterone contribute to blood pressure regulation by promoting water and ion reabsorption, but they differ in their target sites, mechanisms, and release factors. ADH primarily acts on the collecting ducts, while aldosterone acts on the distal convoluted tubules and collecting ducts. ADH causes water reabsorption, while aldosterone causes water and sodium reabsorption. ADH release is mainly stimulated by osmotic factors, while aldosterone release is mainly stimulated by blood pressure and sodium levels.

Comparative Table: ADH vs Aldosterone

Here is a table comparing the differences between ADH and Aldosterone:

In summary, ADH is a peptide hormone produced by the hypothalamus and released from the pituitary gland, while aldosterone is a steroid hormone synthesized and secreted from the adrenal glands. ADH primarily increases water permeability in the collecting duct, leading to increased blood pressure by increasing blood volume. Aldosterone, on the other hand, increases the active reabsorption of Na+ in the collecting duct, resulting in increased blood pressure and blood volume.