What effects does parathyroid hormone have on blood calcium level?

Verified step by step guidance

1. Understand that parathyroid hormone (PTH) is secreted by the parathyroid glands and plays a crucial role in regulating blood calcium levels.
2. Recognize that PTH increases blood calcium levels by stimulating osteoclast activity, which breaks down bone matrix and releases calcium into the bloodstream.
3. Note that PTH enhances calcium reabsorption in the kidneys, reducing calcium excretion in urine and thus conserving calcium in the body.
4. Understand that PTH indirectly increases calcium absorption from the digestive tract by stimulating the production of active vitamin D (calcitriol) in the kidneys, which promotes calcium absorption in the intestines.
5. Summarize that the overall effect of PTH is to raise and maintain blood calcium levels within a normal physiological range.

Key Concepts

Parathyroid Hormone (PTH)

Parathyroid hormone is a peptide hormone secreted by the parathyroid glands that regulates calcium levels in the blood. It increases blood calcium by acting on bones, kidneys, and the intestines, maintaining calcium homeostasis essential for various physiological functions.

Bone Resorption

Bone resorption is the process by which osteoclasts break down bone tissue, releasing calcium and phosphate into the bloodstream. PTH stimulates this process to increase blood calcium levels when they are low, ensuring adequate calcium availability for critical cellular activities.

Calcium Reabsorption in Kidneys

PTH enhances calcium reabsorption in the renal tubules, reducing calcium excretion in urine. This action helps conserve calcium in the body, contributing to elevated blood calcium levels and preventing hypocalcemia.