salivary gland
American Heritage Dictionary:
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salivary gland
n.
A gland that secretes saliva, especially any of three pairs of large glands, the parotid, submaxillary, and sublingual, whose secretions enter the mouth and mingle in saliva.
Britannica Concise Encyclopedia:
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salivary gland
Any of the organs that secrete saliva. Three pairs of major glands secrete saliva into the mouth through distinct ducts: the parotid glands (the largest), between the ear and the back of the lower jaw; the submaxillary glands, along the side of the lower jaw; and the sublingual glands, in the floor of the mouth near the chin. There are also numerous small glands in the tongue, palate, lips, and cheeks. The presence, smell, or thought of food normally increases secretion.
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Oxford Food & Nutrition Dictionary:
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salivary glands
Three pairs of glands in the mouth, which secrete saliva: parotid, submandibular, and submaxillary glands.
Columbia Encyclopedia:
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salivary glands
salivary glands (săl'əvâr'ē), in humans, three pairs of glands that secrete the alkaline digestive fluid, saliva, into the mouth. Most animals have salivary glands that resemble those in humans; however, in some animals these glands perform other functions. For example, the salivary glands of many blood-sucking species secrete a substance that prevents blood coagulation. In humans the largest pair of salivary glands is situated just below and in front of each ear (parotid glands), the second pair is below the jaw (submandibular), and the third is under the tongue (sublingual). Ducts carry the secretions of the salivary glands into the mouth cavity. Together with the mucus secreted by the membrane of the mouth and the secretions of other small glands in the mouth, saliva helps to keep the mouth moist, softens the food as it is chewed, and by means of salivary amylase-the digestive enzyme contained in saliva-converts starch to sugar, thus initiating the process of digestion (see digestive system). The flow of saliva is stimulated by the presence of food in the mouth, or even the sight and smell of food. A lack of salivary flow from a gland may be caused by the formation of a calculus, or mineral concretion, that blocks a duct. The parotid glands are subject to growths, usually benign, and to infection (see mumps).
Dictionary of Cultural Literacy: Health:
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salivary glands
Wiley Dictionary of Flavors:
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Salivary Glands
The organs that produce saliva, located at the sides of the face. Saliva aids in the digestion of food. As for flavors, saliva is an important carrier for volatiles. Being aqueous, saliva affects relative vapor pressures of non-polar volatile organics. Three pairs of glands produce saliva. These include the parotid gland (the largest) located over the jaw and under and in front of the ear, the sublingual gland (under the tongue), and the submandibular gland (under the jaw or mandible). Saliva is often emitted at the mere sight of food. Olfaction is tied into our pleasure centers deep within our brain called the limbic system. Therefore, flavors and food systems stimulate basic bodily functions and probably have major overall effects on our pleasure centers, hormonal balance (enzymes), emotions (limbic), and other fundamental positive results. Research is currently being conducted on proving these theories. Such a scientific response would tend to invalidate negative claims against the flavor industry.
Oxford Dictionary of Biochemistry:
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salivary gland
any of the various glands that discharge saliva into the mouth. In humans there are three pairs: the parotid, sublingual, and submaxillary glands. In snakes they include the venom glands.
| saliva, saline, salicylic acid | |
| salivary juice, salmine, salmon |
Saunders Veterinary Dictionary:
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salivary gland
Any of the glands around the mouth that secrete saliva. The major ones are the three pairs known as the parotid, mandibular or submandibular and sublingual glands. There are other smaller salivary glands within the cheeks, e.g. zygomatic gland, and in the tongue.
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- s. g. inflammation — see sialoadenitis, parotiditis.
- s. g. squamous metaplasia — of the interlobular duct of the salivary gland is a feature of hypovitaminosis A.
Mosby's Dental Dictionary:
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salivary glands
n.pl
Glands in the oral cavity that secrete saliva. Three major groups of salivary glands contribute their secretions to form the whole saliva; minor mucous glands found within oral mucosa contribute also in small part. The primary salivary glands are the parotid, submandibular, and sublingual.
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categories related to 'salivary glands'
- Endocrine System and Glands - salivary glands: three pairs of glands in mouth that secrete saliva: parotid, sublingual, submaxillary
Wikipedia on Answers.com:
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Salivary gland
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This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2007) |
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| Salivary glands: #1 is Parotid gland, #2 is Submandibular gland, #3 is Sublingual gland | |
| Latin | glandulae salivariae |
The salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose. In other organisms such as insects, salivary glands are often used to produce biologically important proteins like silk or glues, and fly salivary glands contain polytene chromosomes that have been useful in genetic research.
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Contents
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Histology
The gland is internally divided into lobules. Blood vessels and nerves enter the glands at the hilum and gradually branch out into the lobules.
Ducts
In the duct system, the lumina are formed by intercalated ducts, which in turn join to form striated ducts. These drain into ducts situated between the lobes of the gland (called interlobar ducts or secretory ducts).
All of the human salivary glands terminate in the mouth, where the saliva proceeds to aid in digestion. The saliva that salivary glands release is quickly inactivated in the stomach by the acid that is present there.
Anatomy
Parotid glands
Main article: Parotid gland
The parotid gland is the largest salivary gland and is found wrapped around the mandibular ramus. The secretion produced is mainly serous in nature and enters the oral cavity via Stensen's duct. You can usually feel this gland, as it is in the upper neck and feels like a rounded ball.
Submandibular glands
Main article: Submandibular gland
The submandibular glands are a pair of glands located beneath the lower jaws, superior to the digastric muscles. The secretion produced is a mixture of both serous fluid and mucus, and enters the oral cavity via Wharton's ducts. Approximately 70% of saliva in the oral cavity is produced by the submandibular glands, even though they are much smaller than the parotid glands.
Sublingual gland
Main article: Sublingual gland
The sublingual glands are a pair of glands located beneath the tongue, anterior to the submandibular glands. The secretion produced is mainly mucus in nature, however it is categorized as a mixed gland. Unlike the other two major glands, the ductal system of the sublingual glands do not have striated ducts, and exit from 8-20 excretory ducts. Approximately 5% of saliva entering the oral cavity come from these glands.
Minor salivary glands
There are over 600 minor salivary glands located throughout the oral cavity within the submucosa[1] of the oral mucosa. They are 1-2mm in diameter and unlike the other glands, they are not encapsulated by connective tissue only surrounded by it. The gland is usually a number of acini connected in a tiny lobule. A minor salivary gland may have a common excretory duct with another gland, or may have its own excretory duct. Their secretion is mainly mucous in nature (except for Von Ebner's glands) and have many functions such as coating the oral cavity with saliva. Problems with dentures are usually associated with minor salivary glands.[2]
Von Ebner's glands
Main article: Von Ebner's glands
Von Ebner's glands are glands found in circumvallate papillae of the tongue. They secrete a serous fluid that begin lipid hydrolysis. They facilitate the perception of taste.
Innervation
Salivary glands are innervated, either directly or indirectly, by the parasympathetic and sympathetic arms of the autonomic nervous system. Both result in increased amylase output and volume flow.
- Parasympathetic innervation to the salivary glands is carried via cranial nerves. The parotid gland receives its parasympathetic input from the glossopharyngeal nerve (CN IX) via the otic ganglion, while the submandibular and sublingual glands receive their parasympathetic input from the facial nerve (CN VII) via the submandibular ganglion. These nerves release acetylcholine and substance P, which activate the IP3 and DAG pathways respectively.
- Direct sympathetic innervation of the salivary glands takes place via preganglionic nerves in the thoracic segments T1-T3 which synapse in the superior cervical ganglion with postganglionic neurons that release norepinephrine, which is then received by β-adrenergic receptors on the acinar and ductal cells of the salivary glands, leading to an increase in cyclic adenosine monophosphate (cAMP) levels and the corresponding increase of saliva secretion. Note that in this regard both parasympathetic and sympathetic stimuli result in an increase in salivary gland secretions.[3] The sympathetic nervous system also affects salivary gland secretions indirectly by innervating the blood vessels that supply the glands.
Role in disease
- See mumps (parotiditis epidemica), Sjögren's syndrome, Mucocele, Graft versus host disease and Salivary gland neoplasm.
Salivary duct calculus may cause blockage of the ducts, causing pain and swelling of the gland because of cysts. Many anti-cancer treatments may impair salivary flow. Radiation therapy may cause permanent xerostomia, whereas chemotherapy may cause only temporary salivary impairment. Graft versus host disease after allogeneic bone marrow transplantation may manifest as dry mouth and many small mucoceles. Tumors of the salivary glands may occur.
A sialogram is a radiocontrast study of a salivary duct.
Saliva production may be pharmacologically stimulated by so called sialagogues (e.g., pilocarpin, cevimeline). It can also be suppressed by so called antisialagogues (e.g., tricyclic antidepressants, SSRI, antihypertensives, polypharmacy).
In other animals
In most vertebrates, saliva does not contain any enzymes, consisting of mucus and water only, and its primary function is to moisten food while eating. As a result, true salivary glands are rarely found in fish or aquatic tetrapods, although there are often individual mucus-secreting cells. Amphibians have a single salivary gland, the intermaxillary gland, located in the forward part of the palate. Reptiles and birds normally have only very small glands on the lips, palate, and base of the mouth, although there are some birds with large glands, which produce a sticky saliva that helps in nest-building. The distinct parotid, submandibular, and sublingual glands are only developed in mammals.[4]
The salivary glands of some species, however, are modified to produce enzymes; salivary amylase is found in many, but by no means all, bird and mammal species (including humans, as noted above). Furthermore, the venom glands of poisonous snakes, Gila monsters, and some shrews, are modified salivary glands.[4]
See also
References
- ^ A.R TEN CATE, "Oral histology. Development, structure, and function".(1998), 2003, 2008
- ^ Cate, A.R. Ten. hi dude Oral Histology: development, structure, and function. 5th ed. 1998. Page 3. ISBN 0-8151-2952-1.
- ^ Costanzo, L. (2006). Physiology, 3rd ed.. Saunders Elsevier. ISBN 10:1-4160-2320-8.
- ^ a b Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 299–300. ISBN 0-03-910284-X.
External links
- Salivary Gland Disorders at intelihealth.com
- Illustration at merck.com
- Illustration at .washington.edu
- plastic/371 at eMedicine - "Parotid Tumors, Benign"
- Medical Encyclopedia Medline Plus: Salivary gland
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American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
Oxford Food & Nutrition Dictionary
A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved.
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Columbia Encyclopedia
The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2012, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/.
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Dictionary of Cultural Literacy: Health
The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and
James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin. All rights reserved.
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Wiley Dictionary of Flavors
Copyright © 2008 by Wiley-Blackwell. Wiley and the Wiley logo are registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other countries. Used here by license. Read more
Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
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Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
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Mosby's Dental Dictionary
Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.
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