Gland: Wikis

  
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Did you know ...


More interesting facts on Gland

Include this on your site/blog:

Encyclopedia

From Wikipedia, the free encyclopedia

Human submaxillary gland. At the right is a group of mucous alveoli, at the left a group of serous alveoli.

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).

Contents

Types

Glands can be divided into 3 groups:

  • Endocrine glands — are glands that secrete their products through the basal lamina and lack a duct system.
  • Exocrine glands — secrete their products through a duct or directly onto the apical surface, 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.

the third type; mixed

Formation

Every gland is formed by an ingrowth from an epithelial surface. This ingrowth may from the beginning possess 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

Additional images

References


Simple English

If you are looking for the city, see Gland (city)

A gland is a special organ. It can be found in animals (and of course humans). A gland makes a special substance. Very often this is a hormone. This substance is then put into the bloodstream. In this case, the gland is called endocrine gland. If the substance is released to somewhere else, the gland is called exocrine gland.

Examples of glands in humans are:

  • Sweat glands that produce sweat for perspiration
  • The pineal gland in the brain, which produces the hormone melatonin at night








Got something to say? Make a comment.
Your name
Your email address
Message