Parathyroid hormone (PTH)

Definition

Parathyroid hormone (PTH) is a hormone secreted by the parathyroid glands that regulates calcium and phosphate balance in the blood and tissues. It increases blood calcium levels by stimulating osteoclast activity, increasing intestinal calcium absorption, and promoting renal calcium reabsorption.

5 Must Know Facts For Your Next Test

1. PTH is produced by the parathyroid glands located behind the thyroid gland.
2. It plays a crucial role in maintaining stable levels of calcium in the blood.
3. PTH acts on bones, kidneys, and the intestines to increase blood calcium levels.
4. Excessive secretion of PTH leads to hyperparathyroidism, which can cause weakened bones and kidney stones.
5. PTH release is regulated by negative feedback from circulating calcium levels.

Review Questions

• What are the main functions of parathyroid hormone (PTH)?
• How does PTH affect bone tissue?
• What conditions can result from hypersecretion or hyposecretion of PTH?

Related terms

Calcitonin: A hormone produced by the thyroid gland that lowers blood calcium levels by inhibiting osteoclast activity.

Hyperparathyroidism: A condition characterized by excessive secretion of PTH leading to elevated blood calcium levels.

Hypocalcemia: A condition where there are abnormally low levels of calcium in the blood, often counteracted by increased PTH secretion.