The four human parathyroid glands are adjacent to the thyroid.

The parathyroid glands are small endocrine glands in the neck, usually located within the thyroid gland, which produce parathyroid hormone. Most often there are four parathyroid glands but some people have six or even eight. Image File history File links Illu_thyroid_parathyroid. ... Image File history File links Illu_thyroid_parathyroid. ... Major endocrine glands. ... A gland is an organ in an animals body that synthesizes a substance for release such as hormones, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). ... Parathyroid hormone (PTH) is secreted by the parathyroid glands as a polypeptide containing 84 amino acids. ...

Anatomy

Human parathyroid glands

The parathyroid glands are four small glands located on the posterior (closer to the back) surface of the thyroid gland. They distinguish themselves from the thyroid gland histologically as they contain two types of cells- parathyroid chief cells and oxyphil cells. Quite easily recognizable from the thyroid as it has densly packed cell as contrasted by the follicle structure of the thyroid. Parathyroid glands From Grays Anatomy 1918 edition This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Parathyroid glands From Grays Anatomy 1918 edition This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Parathyroid chief cells are cells in the parathyroid glands which produce parathyroid hormone. ... Oxyphil cells are cells found in oncocytomas of the kidney, endocrine glands, and salivary glands. ...

Physiology

Parathyroid hormone is a small protein that takes part in the control of calcium and phosphorus homeostasis, as well as bone physiology. When blood calcium levels drop below a certain point, calcium-sensing receptors in the parathyroid gland are activated to release hormone into the blood. It then stimulates osteoclasts to break down bone and release calcium into the blood. The sole purpose of the parathyroid glands is to regulate the calcium level in our bodies within a very narrow range so that the nervous and muscular systems can function properly. Drugs are good. Parathyroid hormone (PTH) is secreted by the parathyroid glands as a polypeptide containing 84 amino acids. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... This article is about the chemical element. ... Homeostasis is the property of an open system, especially living organisms, to regulate its internal environment to maintain a stable, constant condition, by means of multiple dynamic equilibrium adjustments, controlled by interrelated regulation mechanisms. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... An osteoclast is a multinucleated cell that degrades and reabsorbs bone. ...

Role in disease

Disorders of the parathyroid hormone receptor have been associated with Jansen's metaphyseal chondroplasia and Blomstrand's chondroplasia.

The single major disease of parathyroid glands is overactivity of one or more of the parathyroid lobes which make too much parathyroid hormone causing a potentially serious calcium imbalance. This is called hyperparathyroidism; it leads to hypercalcemia and osteitis fibrosa cystica. Since hyperparathyroidism was first described in 1925, the symptoms have become known as "moans, groans, stones, and bones." The primary treatment for this disease is the surgical removal of the faulty gland. Hyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone (PTH). ... Hypercalcaemia is an elevated calcium level in the blood. ... Osteitis fibrosa cystica is characterized by increased osteoclastic resorption of calcified bone with replacement by fibrous tissue. ... Kidney stones, also known as nephrolithiases, urolithiases or renal calculi, are solid accretions (crystals) of dissolved minerals in urine found inside the kidneys or ureters. ... A fractured bone in a living person is typically treated by restoring the fractured pieces of bone to their natural positions (if necessary), and maintaining those positions while the bone heals. ...

A is often used to determine which parathyroid gland(s) are responsible for overproduction of parathyroid hormone.

Embryology

The parathyroid glands originate from endoderm of the third and fourth pharyngeal pouches. It has been suggested that organogenesis be merged into this article or section. ... A pharyngeal pouch is a pulsion diverticulum of the pharyngeal mucosa through Killians dehiscence. ...

External links

• Endocrine Web
• Free Parathyroid Medical Clip Art
• Hypoparathyroidism Support