Citizendia
Your Ad Here

Parathyroid gland
Endocrine system. (Parathyroid gland not pictured, but are present on surface of thyroid gland, as shown below. )
Thyroid and parathyroid.
Latin glandula parathyroidea inferior, glandula parathyroidea superior, Phillip. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Hungerford. Daniel. Mart
Gray's subject #273 1271
Artery superior thyroid artery, inferior thyroid artery,
Vein superior thyroid vein, middle thyroid vein, inferior thyroid vein, thyreoidea ima
Nerve middle cervical ganglion, inferior cervical ganglion
Precursor neural crest mesenchyme and third and fourth pharyngeal pouch endoderm
MeSH Parathyroid+Glands
Dorlands/Elsevier g_06/{{{DorlandsSuf}}}

The parathyroid glands are small endocrine glands in the neck, usually located behind the thyroid gland, which produce parathyroid hormone. Gray's Anatomy the Respiratory apparatus ( Apparatus Respiratorius Respiratory system Respiratory apparatus Arteries are Blood vessels that carry blood away from the Heart. The superior thyroid artery arises from the External carotid artery just below the level of the greater cornu of the Hyoid bone and ends in the Thyroid gland The inferior thyroid artery passes upward in front of the Vertebral artery and Longus colli; then turns medialward behind the Carotid sheath and its contents In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel The superior thyroid vein begins in the substance and on the surface of the Thyroid gland, by tributaries corresponding with the branches of the Superior thyroid artery The middle thyroid vein collects the blood from the lower part of the Thyroid gland, and after being joined by some veins from the Larynx and trachea The inferior thyroid veins two frequently three or four in number arise in the Venous plexus on the Thyroid gland, communicating with the middle and Superior The thyroidea ima ascends in front of the trachea to the lower part of the Thyroid gland, which it supplies A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. The middle cervical ganglion is the smallest of the three Cervical ganglia, and is occasionally absent The inferior cervical ganglion is situated between the base of the transverse process of the last Cervical vertebra and the neck of the First rib, on the medial side Embryology (from Greek grc ἔμβρυον embryon, "unborn embryo" and grc -λογία -logia) is the study of the development The neural crest, a transient component of the Ectoderm, is located in between the Neural tube and the epidermis (or the free margins of the Neural folds Mesenchyme refers to loosely organized connective tissue present in the embryo regardless of origin In Gastroenterology, a pharyngeal pouch is a pathological pulsion Diverticulum of the pharyngeal Mucosa through Killian's dehiscence Endoderm, (sometimes called Entoderm) is one of the Germ layers formed during animal Embryogenesis. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group The endocrine system is an integrated system of small organs that involve the release of extracellular signaling molecules known as Hormones The endocrine system is instrumental A gland is an organ in an animal's body that synthesizes a substance for release such as Hormones or Breast milk, often into the Bloodstream The thyroid is one of the largest Endocrine glands in the body Parathyroid hormone (PTH, or parathormone, is secreted by the Parathyroid glands as a Polypeptide containing 84 Amino acids. In rare cases the parathyroid glands are located within the thyroid glands. The thyroid is one of the largest Endocrine glands in the body Most often there are four parathyroid glands, but some people have six or even eight.

Contents

Anatomy

The parathyroid glands are four or more small glands located on the posterior surface of the thyroid gland. The thyroid is one of the largest Endocrine glands in the body Histologically they are quite easily recognizable from the thyroid as they have densely packed cells in contrast with the follicle structure of the thyroid. The thyroid is one of the largest Endocrine glands in the body [1] However at surgery they are harder to differentiate from the thyroid or fat.

They distinguish themselves from the thyroid gland histologically as they contain two types of cells:[2]

Name Staining Quantity Size Function
parathyroid chief cells darker many[3] smaller manufacture PTH (see below). The thyroid is one of the largest Endocrine glands in the body Parathyroid chief cells are cells in the Parathyroid glands which produce Parathyroid hormone.
oxyphil cells lighter few larger function unknown. [4][5]

History

The parathyroid glands were discovered by Ivar Viktor Sandström (1852-1889), a Swedish medical student, in 1880. Year 1880 ( MDCCCLXXX) was a Leap year starting on Thursday (link will display the full calendar of the Gregorian calendar (or a Leap year [6] It was the last major organ to be recognized in humans.

Physiology

The sole function of the parathyroid glands is to maintain the body's calcium level within a very narrow range, so that the nervous and muscular systems can function properly. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 The nervous system is a Network of specialized cells that communicate information about an animal's surroundings and itself The muscular system is the anatomical system of a species that allows it to move

When blood calcium levels drop below a certain point, calcium-sensing receptors in the parathyroid gland are activated to release hormone into the blood. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 The calcium-sensing receptor (CaSR is a G-protein coupled receptor which senses extracellular levels of Calcium ion

Parathyroid hormone (PTH, also known as parathormone) is a small protein that takes part in the control of calcium and phosphate homeostasis, as well as bone physiology. Parathyroid hormone (PTH, or parathormone, is secreted by the Parathyroid glands as a Polypeptide containing 84 Amino acids. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Homeostasis (from Greek: ὅμος hómos, "equal" and ιστημι istēmi, "to stand" lit Parathyroid hormone has effects antagonistic to those of calcitonin. Parathyroid hormone (PTH, or parathormone, is secreted by the Parathyroid glands as a Polypeptide containing 84 Amino acids. Calcitonin is a 32-amino acid linear polypeptide Hormone that is produced in Humans primarily by the parafollicular (also known as C-cells of the It increases blood calcium levels by stimulating osteoclasts to break down bone and release calcium. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 An osteoclast (from the Greek words for "bone" and "broken" is a type of Bone cell that removes Bone tissue by removing its Mineralized matrix Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 It also increases gastrointestinal calcium absorption by activating vitamin D, and promotes calcium uptake by the kidneys. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Vitamin D is a group of fat-soluble Prohormones, the two major forms of which are vitamin D2 (or Ergocalciferol) and vitamin D3 (or Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 The kidneys are complicated organs that have numerous biological roles

Role in disease

Hyperparathyroidism and related conditions

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. Hyperparathyroidism is overactivity of the Parathyroid glands resulting in excess production of Parathyroid hormone (PTH Parathyroid hormone (PTH, or parathormone, is secreted by the Parathyroid glands as a Polypeptide containing 84 Amino acids. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 This is called hyperparathyroidism; it leads to hypercalcemia and osteitis fibrosa cystica. Hyperparathyroidism is overactivity of the Parathyroid glands resulting in excess production of Parathyroid hormone (PTH Hypercalcaemia (in American English '''Hypercalcemia''' is an elevated calcium level in the Blood. Osteitis fibrosa cystica or osteitis fibrosa, also known as Von Recklinghausen's disease of bone (after Friedrich Daniel von Recklinghausen) is a Since hyperparathyroidism was first described in 1925, the symptoms have become known as "moans, groans, stones, and bones. Hyperparathyroidism is overactivity of the Parathyroid glands resulting in excess production of Parathyroid hormone (PTH Kidney stones, also called renal calculi, are solid concretions (crystal aggregations of dissolved minerals in Urine; calculi typically form A bone fracture (sometimes abbreviated # or Fx or Fx) is a medical condition in which a Bone is cracked or broken " The primary treatment for this disease is the surgical removal of the faulty gland.

Modern high frequency ultrasound can see parathyroid masses, even before they cause high calcium. The parathyroid glands are small endocrine Glands in the neck usually located behind the Thyroid gland, which produce Parathyroid hormone. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 They are called parathyroid incidentalomas. If a patient has elevated calcium, the ultrasound can be used to locate the abnormal glands. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 The use of ultrasound guided FNA, and parathyroid hormone washings can confirm the abnormal glands. "FNA" redirects here For the botanical book series see Flora of North America North of Mexico. Parathyroid hormone (PTH, or parathormone, is secreted by the Parathyroid glands as a Polypeptide containing 84 Amino acids. A blood calcium 15-30 minutes after the biopsy can help determine if the disease is caused by a single abnormal gland or multiple glands.

A drop in serum calcium suggests a single source, and no drop suggests multiple glands. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 This, with a non-localizing Sestamibi scan would point toward a neck exploration, rather than a minimally invasive method aimed a single gland disease.

A Sestamibi scan is often used to determine which parathyroid gland(s) are responsible for overproduction of parathyroid hormone. A sestamibi scan of the Parathyroid gland is a Nuclear medicine procedure which is performed to identify Hyperparathyroidism (or Parathyroid adenoma

Another related condition is called secondary hyperparathyroidism, or secondary HPT - common in patients with chronic kidney disease on dialysis. In secondary HPT, the parathyroid glands make too much parathyroid hormone (PTH), and the kidneys do not produce enough vitamin D, and calcium and phosphorus are out of balance. Even though one may not have any symptoms, treating secondary HPT is important. Cinacalcet (Sensipar) is a medicine that can help treat such dialysis patients and is available by prescription only.

Hypoparathyroidism and related conditions

Embryology and Evolution

The parathyroid glands originate from the interaction of neural crest mesenchyme and third and fourth pharyngeal pouch endoderm. The neural crest, a transient component of the Ectoderm, is located in between the Neural tube and the epidermis (or the free margins of the Neural folds Mesenchyme refers to loosely organized connective tissue present in the embryo regardless of origin In Gastroenterology, a pharyngeal pouch is a pathological pulsion Diverticulum of the pharyngeal Mucosa through Killian's dehiscence Endoderm, (sometimes called Entoderm) is one of the Germ layers formed during animal Embryogenesis.

Genetically, Eya-1 (transcripitonal co-activator), Six-1 (a homeobox transcription factor), and Gcm-2 (a transcription factor) have been associated with the development of the parathyroid gland, and alterations in these genes alters parathyroid gland development.

The conserved homology of genes and calcium sensing receptors in fish gills with those in the parathryroid glands of birds and mammals is recognized by evolutionary developmental biology as evolution using genes and gene networks in novel ways to generate new structures with some similar functions and novel functions. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Evolutionary developmental biology ( evolution of development or informally evo-devo) is a field of Biology that compares the developmental processes

Additional images

Scheme showing development of branchial epithelial bodies. I, II, III, IV. Branchial pouches. In the development of vertebrate animals, Pharyngeal or branchial pouches form on the endodermal side between the Branchial arches and pharyngeal

Human parathyroid glands

References

  1. ^ Histology at BU 15001ooa
  2. ^ Histology at BU 15002loa
  3. ^ Histology at USC end/c_28
  4. ^ Histology at OU 40_06
  5. ^ Histology at USC end/c_34
  6. ^ Eknoyan G. A gland is an organ in an animal's body that synthesizes a substance for release such as Hormones or Breast milk, often into the Bloodstream For similarly-named academic institutions see Education in Boston MA. For similarly-named academic institutions see Education in Boston MA. The University of Southern California (commonly referred to as USC, SC, Southern California, and incorrectly University of Oklahoma, abbreviated OU, is a Coeducational public Research university located in the U The University of Southern California (commonly referred to as USC, SC, Southern California, and incorrectly . (1995). "A history of the parathyroid glands". Am J Kidney Dis 26 (5): 801-7. doi:10.1016/0272-6386(95)90447-6. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 7485136.  

External links

eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors The University of Southern California (commonly referred to as USC, SC, Southern California, and incorrectly The University of Iowa, is a major teaching service and Research university located on a campus in Iowa City Iowa, on the banks of the Iowa River

Dictionary

parathyroid gland

-noun

  1. (anatomy) Any one of four endocrine glands situated in the neck, usually within a thyroid gland, which produce parathyroid hormone.
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic