The parathyroid glands are located in the neck, just behind the butterfly shaped thyroid gland. Parathyroid hormone is secreted from four parathyroid glands, which are small glands in the neck, located behind the thyroid gland.

The Parathyroid Gland: Location and Secretion

The parathyroid gland is a small endocrine gland located in the neck, specifically behind the thyroid gland. It consists of four small oval-shaped glands, each about the size of a grain of rice. The parathyroid glands are usually found on the posterior surface of the thyroid gland, two on each side.

Function and Secretion

The main function of the parathyroid gland is to regulate the levels of calcium and phosphorus in the body. It does so by secreting a hormone called parathyroid hormone (PTH) or parathormone. PTH acts on various target organs to maintain the balance of calcium and phosphorus in the blood.

Control of Secretion

The secretion of parathyroid hormone is regulated by the negative feedback mechanism in response to the levels of calcium in the blood. When the calcium levels in the blood decrease, the parathyroid gland is stimulated to release more PTH. On the other hand, when the calcium levels rise, the secretion of PTH is inhibited.

Actions of Parathyroid Hormone

Once released into the bloodstream, parathyroid hormone has several effects on the body:

1. Stimulates Osteoclast Activity: PTH stimulates the activity of osteoclasts, which are cells responsible for breaking down bone tissue. This process releases calcium and phosphorus from the bone into the bloodstream.

2. Inhibits Calcium Excretion: PTH reduces the excretion of calcium through the kidneys, increasing its reabsorption. This helps to maintain the calcium levels in the blood.

3. Stimulates Calcium Absorption: PTH enhances the absorption of calcium from the intestines, increasing its uptake into the bloodstream.

4. Promotes Phosphorus Excretion: PTH increases the excretion of phosphorus through the kidneys, reducing its levels in the blood.

5. Stimulates Vitamin D Activation: PTH stimulates the activation of vitamin D in the kidneys. Activated vitamin D helps in the absorption of calcium from the intestines.

Importance in the Body

The parathyroid gland plays a crucial role in maintaining the balance of calcium and phosphorus in the body. Proper levels of calcium are necessary for various bodily functions, including muscle contraction, nerve transmission, blood clotting, and bone health. The secretion of parathyroid hormone ensures that these levels are regulated and maintained within a narrow range.

In conclusion, the parathyroid gland is located behind the thyroid gland and secretes parathyroid hormone (PTH) to regulate calcium and phosphorus levels in the body. PTH acts on various organs to stimulate calcium release from bones, increase calcium absorption, reduce calcium excretion, promote phosphorus excretion, and activate vitamin D. Maintaining proper calcium levels is essential for overall bodily functions and bone health.