kerääjätubuleissa

Kerääjätubulukset, also known as collecting tubules, are essential components of the nephron in the mammalian kidney. These tubules are responsible for reabsorbing water and electrolytes, thereby concentrating urine and maintaining the body's fluid and electrolyte balance. They receive filtrate from the distal convoluted tubules and convey it towards the renal pelvis.

The collecting tubules are lined by principal cells and intercalated cells. Principal cells play a crucial role in regulating sodium and water reabsorption, primarily influenced by antidiuretic hormone (ADH) and aldosterone. ADH increases the permeability of the collecting tubule to water, allowing more water to be reabsorbed from the filtrate back into the bloodstream, thus concentrating urine. Aldosterone promotes sodium reabsorption and potassium secretion.

Intercalated cells, on the other hand, are involved in acid-base balance. Type A intercalated cells secrete hydrogen ions, contributing to the acidification of urine, while type B intercalated cells reabsorb hydrogen ions and secrete bicarbonate ions, helping to alkalinize the blood. The precise function of collecting tubules is vital for homeostasis, ensuring that the body does not lose excessive water or essential salts and that the pH of the blood is maintained within a narrow range. Their activity is finely tuned by hormonal signals and the body's overall physiological state.