PTH

Definition

PTH, or parathyroid hormone, is a crucial hormone produced by the parathyroid glands that plays a central role in regulating calcium and phosphate homeostasis within the body. It is intimately connected to the topics of 'An Overview of the Endocrine System' and 'The Parathyroid Glands'.

5 Must Know Facts For Your Next Test

1. PTH increases blood calcium levels by stimulating the release of calcium from bone, increasing calcium absorption in the intestines, and decreasing calcium excretion by the kidneys.
2. PTH also regulates phosphate levels by decreasing reabsorption of phosphate in the kidneys, leading to increased phosphate excretion.
3. Secretion of PTH is primarily controlled by the concentration of calcium in the blood, with low calcium levels triggering increased PTH release.
4. Chronic overproduction of PTH can lead to a condition called hyperparathyroidism, which is characterized by high blood calcium levels and weakened bones.
5. Decreased PTH secretion, or hypoparathyroidism, can result in low blood calcium levels and associated symptoms like muscle spasms and seizures.

Review Questions

• Explain how PTH helps maintain calcium homeostasis in the body.
  • PTH is the primary regulator of calcium homeostasis. When blood calcium levels drop, the parathyroid glands secrete PTH, which then acts on the bones, kidneys, and intestines to increase calcium levels. Specifically, PTH stimulates the release of calcium from bone, increases calcium absorption in the gut, and reduces calcium excretion by the kidneys. This multifaceted action of PTH helps restore normal blood calcium concentrations and maintain calcium balance within a tight physiological range.
• Describe the relationship between PTH and phosphate homeostasis.
  • In addition to its role in calcium regulation, PTH also influences phosphate homeostasis. PTH decreases reabsorption of phosphate in the kidneys, leading to increased phosphate excretion. This helps maintain the proper balance between calcium and phosphate levels, which is crucial for bone health and various other physiological processes. The interplay between PTH, calcium, and phosphate is essential for overall mineral homeostasis in the body.
• Analyze the potential consequences of dysregulation of PTH secretion.
  • Imbalances in PTH secretion can have significant health implications. Chronic overproduction of PTH, known as hyperparathyroidism, can result in high blood calcium levels and weakened bones, increasing the risk of fractures. Conversely, decreased PTH secretion, or hypoparathyroidism, can lead to low blood calcium levels, causing symptoms like muscle spasms and seizures. Maintaining proper PTH levels is crucial for regulating calcium and phosphate homeostasis, and dysregulation of PTH can have far-reaching effects on various physiological systems, underscoring the importance of this hormone in endocrine function.

Related terms

Calcium Homeostasis:

The process of maintaining a stable concentration of calcium in the blood and extracellular fluids, which is essential for proper nerve, muscle, and bone function.

Phosphate Homeostasis: The regulation of phosphate levels in the body, which is important for bone health, energy production, and various other physiological processes.

Parathyroid Glands:

Four small endocrine glands located behind the thyroid gland that secrete PTH to help maintain calcium and phosphate balance.