What mechanism regulates the absorption of calcium in the distal tubule of the nephron?

The regulation of calcium absorption in the distal tubule of the nephron is primarily controlled by parathyroid hormone (PTH). When calcium levels in the blood decrease, the parathyroid glands release PTH, which serves several key functions in maintaining calcium homeostasis. One of those functions is enhancing the reabsorption of calcium in the distal convoluted tubule of the nephron.

PTH acts on specific receptors in the distal tubule cells, leading to increased activity of calcium channels and transporters that facilitate the movement of calcium from the tubular fluid back into the blood. By upregulating these channels, PTH effectively increases the reabsorption rate of calcium, thereby helping to raise blood calcium levels when necessary.

This regulation is critical for numerous physiological processes, including bone health, muscle function, and blood coagulation. Understanding the role of PTH in calcium absorption is essential for grasping how the body maintains the balance of this vital mineral.