AskDefine | Define gland

Dictionary Definition

gland n : any of various organs that synthesize substances needed by the body and release it through ducts or directly into the bloodstream [syn: secretory organ, secretor, secreter]

User Contributed Dictionary

English

Etymology 1

17th century. Latin (via French) glandula “tonsil” < glans “acorn”.

Noun

  1. an organ which secretes something
  2. a secretory structure on the surface of an organ.
Related terms
Translations

See also

Etymology 2

19th century. Etymology unknown.

Noun

gland
  1. (mechanical) a compressable cylindrical case and its contents around a shaft where it passes through a barrier, intended to prevent the passage of a fluid past the barrier. Examples:
    a. used around a ship’s propeller shaft.
    b. used around a tap, valve or faucet.

French

Pronunciation

Noun

gland

Romanian

Noun

gland

Extensive Definition

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 (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).

Types

Glands can be divided into two groups:
  • Endocrine glands — are glands that secrete their product directly onto a surface rather than through a duct.
  • Exocrine glands — secrete their products via a duct, the glands in this group can be divided into three groups:
    • Apocrine glands — a portion of the secreting cell's body is lost during secretion. Apocrine gland is often used to refer to the apocrine sweat glands, however it is thought that apocrine sweat glands may not be true apocrine glands as they may not use the apocrine method of secretion.
    • Holocrine glands — the entire cell disintegrates to secrete its substances (e.g., sebaceous glands)
    • Merocrine glands — cells secrete their substances by exocytosis (e.g., mucous and serous glands). Also called "eccrine."
The type of secretory product of an Exocrine gland may also be one of three categories:
  • Serous glands — secrete a watery, often protein-rich product.
  • Mucous glands — secrete a viscous product, rich in carbohydrates (e.g., glycoproteins).
  • Sebaceous glands — secrete a lipid product.

Formation

Every gland is formed by an ingrowth from an epithelial surface. This ingrowth may from the beginning possess be a tubular structure, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated.
As growth proceeds, the column of cells may divide or give off offshoots, in which case a compound gland is formed. In many glands the number of branches is limited, in others (salivary, pancreas) a very large structure is finally formed by repeated growth and sub-division. As a rule, the branches do not unite with one another, but in one instance, the liver, this does occur when a reticulated compound gland is produced. In compound glands the more typical or secretory epithelium is found forming the terminal portion of each branch, and the uniting portions form ducts and are lined with a less modified type of epithelial cell.
Glands are classified according to their shape.
  • If the gland retains its shape as a tube throughout it is termed a tubular gland.
  • In the second main variety of gland the secretory portion is enlarged and the lumen variously increased in size. These are termed alveolar or saccular glands.

Specific glands

A list of human exocrine glands is available here.
A list of human endocrine glands is available here.

Crypts of Lieberkuhn

The Crypts of Lieberkuhn in the lower gastrointestinal tract are also referred to as "glands."

Additional images

submaxillary gland of kitten. Duct semidiagrammatic. pancreas of dog. X 250. breast. mamma. Image:Drüse Kopie.jpg|Methods of secretion

References

gland in Arabic: غدة
gland in Bulgarian: Жлеза
gland in Catalan: Glàndula
gland in Czech: Žláza
gland in Danish: Kirtel
gland in German: Drüse
gland in Modern Greek (1453-): Αδένας
gland in Spanish: Glándula
gland in Esperanto: Glando
gland in Persian: غده
gland in French: Glande
gland in Galician: Glándula
gland in Indonesian: Kelenjar
gland in Interlingua (International Auxiliary Language Association): Glandula
gland in Italian: Ghiandola
gland in Hebrew: בלוטה
gland in Pampanga: Gland
gland in Latin: Glandula
gland in Lithuanian: Liauka
gland in Macedonian: Жлезда
gland in Dutch: Klier
gland in Japanese: 腺
gland in Norwegian: Kjertel
gland in Norwegian Nynorsk: Kjertel
gland in Polish: Gruczoł
gland in Portuguese: Glândula
gland in Romanian: Glandă
gland in Sicilian: Ghiànnula
gland in Simple English: Gland
gland in Slovenian: Žleza
gland in Serbian: Жлезда
gland in Finnish: Rauhanen
gland in Swedish: Körtel
gland in Telugu: గ్రంధి
gland in Turkish: Bez
gland in Ukrainian: Залоза
gland in Yiddish: גלענד
gland in Chinese: 腺体

Synonyms, Antonyms and Related Words

acromegaly, adrenal, breast, choriocarcinoma, cretinism, diabetes, diabetes insipidus, diabetes mellitus, dwarfism, gasket, giantism, hyperglycemia, hyperparathyroidism, hypo-ovarianism, hypothyroidism, liver, mamma, mammary gland, ovary, packing, padding, pancreas, panhypopituitarism, pheochromocytoma, pineal body, prostate, prostate gland, sexual precocity, spermary, stopping, stuffing, tampon, testicle, thyroid, thyroid gland, thyrotoxicosis, toxic goiter, wadding
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