key term - Parathyroid Hormone

Definition

Parathyroid hormone (PTH) is a key regulator of calcium and phosphate metabolism in the body, secreted by the parathyroid glands. It plays a crucial role in maintaining calcium homeostasis by increasing blood calcium levels when they drop too low, which connects it to various physiological processes involving hormone regulation, endocrine function, and bone health.

5 Must Know Facts For Your Next Test

1. Parathyroid hormone is produced by the chief cells of the parathyroid glands and is released when blood calcium levels are low.
2. PTH stimulates osteoclasts to increase bone resorption, releasing calcium from bones into the bloodstream.
3. It promotes renal reabsorption of calcium while increasing phosphate excretion in the kidneys, helping to balance mineral levels.
4. PTH also stimulates the conversion of vitamin D into its active form, calcitriol, enhancing intestinal absorption of calcium.
5. Excessive production of parathyroid hormone can lead to hyperparathyroidism, characterized by high blood calcium levels and potential bone density loss.

Review Questions

• How does parathyroid hormone influence bone remodeling and overall calcium balance in the body?
  • Parathyroid hormone influences bone remodeling primarily by stimulating osteoclasts, which break down bone tissue and release calcium into the bloodstream. This process increases blood calcium levels when they fall too low. Additionally, PTH promotes calcium reabsorption in the kidneys and activates vitamin D to enhance dietary calcium absorption. Together, these actions help maintain overall calcium balance and support vital physiological functions.
• Evaluate the relationship between parathyroid hormone and vitamin D in regulating mineral metabolism.
  • The relationship between parathyroid hormone and vitamin D is crucial for effective regulation of mineral metabolism. When blood calcium levels are low, PTH is secreted, which not only increases bone resorption but also stimulates the conversion of vitamin D into its active form, calcitriol. Calcitriol then enhances intestinal absorption of calcium. This synergy ensures that both hormones work together to maintain adequate calcium levels in the bloodstream.
• Discuss the implications of abnormal parathyroid hormone secretion on bone health and overall mineral homeostasis.
  • Abnormal secretion of parathyroid hormone can lead to significant health issues, particularly concerning bone health and mineral homeostasis. In conditions like hyperparathyroidism, excessive PTH leads to increased bone resorption and loss of bone density, increasing fracture risk. Conversely, insufficient PTH can result in hypoparathyroidism, causing low blood calcium levels and potentially leading to muscle spasms and seizures. Both scenarios highlight the critical role of PTH in maintaining not just bone integrity but also overall mineral balance within the body.

Related terms

Calcium Homeostasis: The process through which the body maintains stable levels of calcium in the blood and tissues, critical for proper physiological function.

Vitamin D: A fat-soluble vitamin that aids in the absorption of calcium and phosphate in the intestines and works in conjunction with parathyroid hormone to regulate calcium levels.

Osteoclasts:

Specialized cells that break down bone tissue, increasing calcium release into the bloodstream in response to parathyroid hormone.