Gland

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Gland
Gray1026.png
Human submaxillary gland. At the right is a group of mucous alveoli, at the left a group of serous alveoli.
Latinglandula
CodeTH H2.00.02.0.02002
Anatomical terminology
 
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For other uses, see Gland (disambiguation).
"Glandula" redirects here. It is not to be confused with Gianduia (disambiguation).
Gland
Gray1026.png
Human submaxillary gland. At the right is a group of mucous alveoli, at the left a group of serous alveoli.
Latinglandula
CodeTH H2.00.02.0.02002
Anatomical terminology

A gland is an organ in an animal's body that synthesizes a substance such as hormones for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).

Structure[edit]

Glands are organs in that synthesizes a substance such as hormones for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Numerous glands exist throughout the human body.

Development[edit]

This image shows some of the various possible glandular arrangements. These are the simple tubular, simple branched tubular, simple coiled tubular, simple acinar, and simple branched acinar glands.
This image shows some of the various possible glandular arrangements. These are the compound tubular, compound acinar, and compound tubulo-acinar glands.

Every gland is formed by an ingrowth from an epithelial surface. This ingrowth may in 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.

Function[edit]

Glands are divided based on their function into two groups:

Endocrine glands[edit]

Main article: Endocrine gland

Endocrine glands secrete substances that circulate through the blood stream. These glands that secrete their products through the basal lamina into the blood stream and lack a duct system. These glands often secrete hormones, and play an important role in maintaining homeostasis. The pineal gland, thymus gland, pituitary gland, thyroid gland, and the two adrenal glands are all endocrine glands.

Exocrine glands[edit]

Main article: Exocrine gland

Exocrine glands secrete their products through a duct onto an outer surface of the body, such as the skin or the human gastrointestinal tract. Secretion is directly onto the apical surface. The glands in this group can be divided into three groups:

The type of secretory product of exocrine glands may also be one of three categories:

Clinical significance[edit]

Other animals[edit]

Additional images[edit]

References[edit]

Public Domain This article incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. 

External links[edit]