Exocrine gland
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Exocrine glands are
gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormone A hormone (from the Greek participle , "setting in motion") is any member of a class of signaling molecules in multicellular organisms, ...

gland
s that secrete substances onto an
epithelial Epithelium is one of the four basic types of animal Tissue (biology), tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed Cell (biology), cells with little Extr ...
surface by way of a duct. Examples of exocrine glands include
sweat Perspiration, also known as sweating, is the production of fluids secreted by the sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin Skin is the layer of usually soft, fle ...
,
salivary The salivary glands in mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which in Female#Mammalia ...
,
mammary A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organ (anatomy), organs such as the b ...
, ceruminous, lacrimal gland, lacrimal, sebaceous, prostate and mucous. Exocrine glands are one of two types of glands in the human body, the other being endocrine glands, which secrete their products directly into the bloodstream. The liver and pancreas are both exocrine and endocrine glands; they are exocrine glands because they secrete products—bile and pancreatic juice—into the human gastrointestinal tract, gastrointestinal tract through a series of ducts, and endocrine because they secrete other substances directly into the bloodstream.


Classification


Structure

Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland. * The duct portion may be branched (called compound) or unbranched (called simple). * The glandular portion may be tubular gland, tubular or acinar gland, acinar, or may be a mix of the two (called tubuloacinar). If the glandular portion branches, then the gland is called a branched gland.


Method of secretion

Exocrine glands are named apocrine glands, holocrine glands, or merocrine glands based on how their products are secreted. * Merocrine secretion – cells excrete their substances by exocytosis into a duct; for example, pancreatic acinar cells, maximum Sweat gland, sweat glands of humans, Salivary gland, salivary glands, Goblet cell, goblet cells, Intestinal gland, intestinal glands, Lacrimal gland, tear glands, etc. * Apocrine secretion – apical portion of the cytoplasm in the cell membrane that contains the excretion buds off. Examples are sweat glands of arm pits, pubic region, skin around anus, lips and nipples; Mammary gland, mammary glands, etc. * Holocrine secretion – the entire cell disintegrates to excrete its substance; for example, sebaceous glands of the skin and nose, meibomian gland, Gland of Zeis, zeis gland, etc.


Product secreted

* Serous gland, Serous cells secrete proteins, often enzymes. Examples include gastric chief cells and Paneth cells * Mucous gland, Mucous cells secrete mucus. Examples include Brunner's glands, esophageal glands, and pyloric glands * Seromucous glands (mixed) secrete both protein and mucus. Examples include the salivary glands: although the parotid gland (saliva secretion 25%) is predominantly serous, the sublingual gland (saliva secretion 5%) mainly mucous gland, and the submandibular gland (saliva secretion 70%) is a mixed, mainly serous gland. * Sebaceous glands secrete Sebaceous gland#Sebum, sebum, a lipid product. These glands are also known as oil glands, e.g. Fordyce spots and Meibomian glands.


Additional images

File:Gray1033.png, Section of the human esophagus. File:Gray1172.png, Dissection of a lactating breast.


See also

* List of glands of the human body * List of specialized glands within the human integumentary system


References


External links


Diagram at mhhe.com
{{Authority control Exocrine system