The parathyroid hormone

The parathyroid hormone, called parathormone, regulates the calcium-phosphate balance between the blood and other tissues.

Production of this hormone is directly controlled by the calcium concentration of the extracellular fluid bathing the cells of these glands.

Parathormone exerts at least the following five effects:

 

(1)it increases gastrointestinal absorption of calcium by stimulating the active transport system and moves calcium from the gut lumen into the blood;

(2) it increases the movement of calcium and phosphate from bone into extracellular fluid. This is accomplished by stimulating osteoclasts to break down bone structure, thus liberating calcium phosphate into the blood. In this way, the store of calcium contained in bone is tapped;

(3)it increases re-absorption of calcium by the renal tubules, thereby decreasing urinary calcium excretion;

(4)it reduces the re-absorption of phosphate by the renal tubules

(5)it stimulates the synthesisof 1,25-dihydrixycholecalciferol by the kidney.

 

        

If parathyroid glands are removed accidentally during surgery on the thyroid, there would be arise in the phosphate concentration in the blood.

There would also be a drop in the calcium concentration as more calcium is excreted by the kidneys and intestines, and more incorporated into the bone.

This can produce serious disturbances, particularly in the muscles and nerves, which use calcium ions for normal functioning.

Over activity of the parathyroid glands, which can result from a tumor on the glands, produces a weakening of the bones.

This is a condition that makes them much more vulnerable to fracturing because of excessive withdrawal of calcium from the bones.

Sumber : Bpk. Dr. Iskandar Zulkarnain

#posting tugas cyberprenership

    ahmad baihaqi

    NIM 1112503964

 

 

 

Parathyroid Gland

Parathyroid gland

   

    There are four parathyroid glands. They are small, light-colored lumps that stick out from the surface of the thyroid gland. All four glands are located on the thyroid gland.

They are butterfly-shaped and located inside the neck, more specifically on both sides of the windpipe.

   One of the parathyroid glands most important functions is to regulate the body's calcium and phosphorus levels. Another function of the parathyroid glands is to secrete parathyroid hormone, which causes the release of the calcium present in bone to extracellular fluid.

PTH does this by depressing the production of osteoblasts, special cells of the body involved in the production of bone and activating osteoclasts, other specialized cells involved in the removal of bone.

Receptors bind a specific hormone and the result is a specific physiologic response, meaning a normal response of the body.

    PTH finds its major target cells in bone, kidneys, and the gastrointestinal system.

Calcitonin, a hormone produced by the thyroid gland that also regulates ECF calcium levels and serves to counteract the calcium-producing effects of PTH.

    The adult body contains as much as 1 kg of calcium. Most of this calcium is found in bone and teeth. The four parathyroid glands secrete the parathyroid hormone (PTH). It opposes the effect of thyrocalcitonin. It does this by removing calcium from its storage sites in bones, releasing it into the bloodstream. It also signals the kidneys to reabsorb more of this mineral, transporting it into the blood. It also signals the small intestine to absorb more of this mineral, transporting it from the diet into the blood.

    Calcium is important for steps of body metabolism. Blood cannot clot without sufficient calcium. Skeletal muscles require this mineral in order to contract. A deficiency of PTH can lead to tetany, muscle weakness due to lack of available calcium in the blood.

Sumber : Bpk. Dr. Iskandar Zulkarnain

#posting tugas cyberprenership

    ahmad baihaqi

    NIM 1112503964