Collecting duct system

Collecting duct system is a part of the kidney's nephron that plays a crucial role in the body's water balance and electrolyte balance. It is the final component of the nephron where the urine is collected before it is transported to the renal pelvis and ureter.

Structure

The collecting duct system is composed of two main parts: the cortical collecting duct and the medullary collecting duct. These ducts are lined with two types of cells: principal cells and intercalated cells. Principal cells are responsible for the reabsorption of sodium and water and the secretion of potassium, while intercalated cells are involved in the regulation of acid-base balance.

Function

The primary function of the collecting duct system is to fine-tune the amount of water, sodium, and potassium that is reabsorbed back into the body and the amount that is excreted in the urine. This process is regulated by two hormones: antidiuretic hormone (ADH) and aldosterone. ADH increases the permeability of the collecting duct to water, allowing more water to be reabsorbed back into the body. Aldosterone increases the reabsorption of sodium and the secretion of potassium.

Clinical significance

Abnormalities in the collecting duct system can lead to various kidney disorders. For example, nephrogenic diabetes insipidus is a condition caused by a defect in the collecting duct's response to ADH, resulting in excessive urine production. Polycystic kidney disease is another condition that can affect the collecting duct, leading to the formation of multiple cysts in the kidney.

See also

• Nephron
• Renal physiology
• Kidney disease