What effect does parathyroid hormone have on the body?

Parathyroid hormone (PTH) plays a crucial role in the regulation of calcium levels in the body. When released from the parathyroid glands, PTH acts primarily to increase blood calcium levels. It achieves this by stimulating three main processes:

1. Bone Resorption: PTH promotes the release of calcium from bones into the bloodstream by stimulating osteoclasts, the cells responsible for breaking down bone tissue. This process raises the concentration of calcium in the blood.

2. Renal Reabsorption: PTH increases the reabsorption of calcium in the kidneys, which helps to conserve calcium and prevent its loss through urine. This reabsorption directly contributes to higher blood calcium levels.

3. Intestinal Absorption: PTH indirectly increases intestinal absorption of calcium by stimulating the production of active vitamin D (calcitriol) in the kidneys, which enhances calcium absorption from dietary sources in the intestines.

This multifaceted action of parathyroid hormone leads to an overall increase in the calcium levels in the bloodstream, making the answer regarding its effect correct. Other choices listed do not accurately reflect PTH's primary functions, as it does not lower blood calcium levels, stimulate muscle contraction directly, or regulate insulin