Question

PTH (parathyroid hormone) acts on the __________ to __________ Ca2+ reabsorption.

1) liver; decrease
2) bones; decrease
3) DCT; increase
4) arge intestine; increase

Answer 1

PTH acts on the distal convoluted tubule (DCT) to increase calcium reabsorption. It is released from the parathyroid glands in response to low blood calcium levels. By acting on the kidneys and stimulating calcitriol production, PTH helps maintain normal blood calcium levels.

Step-by-step explanation:

Parathyroid hormone (PTH) acts on the kidneys, specifically on the distal convoluted tubule (DCT), to increase calcium (Ca2+) reabsorption. When blood calcium levels are low, PTH is released from the parathyroid glands. In the kidneys, PTH's role is to decrease the excretion of calcium by increasing its reabsorption in the DCT. This helps to maintain blood calcium levels within the normal range. Also, PTH stimulates the formation of calcitriol (active vitamin D) in the kidneys, which then acts to increase dietary calcium absorption in the intestines.