Pancreas
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{{Infobox Anatomy |
Name = '''Pancreas''' |
Latin = |
GraySubject = 251 |
GrayPage = 1199 |
Image = Illu pancrease.jpg |
Caption = |
Image2 = illu_pancreas_duodenum.jpg |
Caption2 = 1: [[Head of pancreas]]<BR>2: [[Uncinate process of pancreas]]<BR>3: [[Pancreatic notch]]<BR>4: [[Body of pancreas]]<BR>5: [[Anterior surface of pancreas]]<BR>6: [[Inferior surface of pancreas]]<BR>7: [[Superior margin of pancreas]]<BR>8: [[Anterior margin of pancreas]]<BR>9: [[Inferior margin of pancreas]]<BR>10: [[Omental tuber]]<BR>11: [[Tail of pancreas]]<BR>12: [[Duodenum]] |
Precursor = [[pancreatic bud]]s |
System = |
Artery = [[inferior pancreaticoduodenal artery]], [[superior pancreaticoduodenal artery]], [[splenic artery]] |
Vein = [[pancreaticoduodenal veins]], [[pancreatic veins]] |
Nerve = [[pancreatic plexus]], [[celiac ganglia]], [[vagus]]<ref>{{GeorgiaPhysiology|6/6ch2/s6ch2_30}}</ref> |
Lymph = |
MeshName = Pancreas|
MeshNumber = A03.734 |
DorlandsPre = p_02 |
DorlandsSuf = |
}}
The '''pancreas''' is a [[gland]] [[Organ (anatomy)|organ]] in the [[digestive system|digestive]] and [[endocrine system]] of [[vertebrates]]. It is both [[Exocrine gland|exocrine]] (secreting [[pancreatic juice]] containing [[Digestion|digestive]] [[enzyme]]s) and [[endocrine system|endocrine]] (producing several important [[hormone]]s, including [[insulin]], [[glucagon]], and [[somatostatin]]). It also produces digestive enzymes that pass into the [[small intestine]]. These enzymes help in the further breakdown of the [[carbohydrates]], [[protein]], and [[fat]] in the [[chyme]].
==Histology==
Under a [[microscope]], stained sections of the pancreas reveal two different types of [[parenchyma]]l tissue.<ref>{{BUHistology|10404loa}}</ref> Lightly staining clusters of cells are called [[islets of Langerhans]], which produce [[hormone]]s that underlie the [[endocrine gland|endocrine]] functions of the pancreas. Darker staining cells form [[pancreatic acini|acini]] connected to [[exocrine duct|ducts]]. Acinar cells belong to the [[exocrine pancreas]] and secrete [[digestive enzyme]]s into the gut via a system of ducts.
{| class="wikitable"
| '''Structure''' || '''Appearance''' || '''Function'''
|-
| [[Islets of Langerhans]] || Lightly staining, large, spherical clusters || [[Hormone]] production and secretion ([[endocrine pancreas]])
|-
| [[Exocrine pancreas|Pancreatic acini]] || Darker staining, small, berry-like clusters || [[Digestive enzyme]] production and secretion ([[exocrine pancreas]])
|}
==Function==
The pancreas is a dual-function gland, having features of both [[endocrine gland|endocrine]] and [[exocrine gland]]s.
===Endocrine===
{{main|Endocrine pancreas}}
The part of the pancreas with endocrine function is made up of a million<ref>{{cite journal |author=Hellman B, Gylfe E, Grapengiesser E, Dansk H, Salehi A |title=[Insulin oscillations--clinically important rhythm. Antidiabetics should increase the pulsative component of the insulin release] |language=Swedish |journal=Lakartidningen |volume=104 |issue=32-33 |pages=2236–9 |year=2007 |pmid=17822201 |doi=}}</ref> cell clusters called [[islets of Langerhans]]. There are four main cell types in the islets. They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion: α cells secrete [[glucagon]], β cells secrete [[insulin]], δ cells secrete [[somatostatin]], and PP cells secrete [[pancreatic polypeptide]].<ref>BRS physiology 4th edition ,page 255-256, Linda S. Constanzo, Lippincott publishing</ref>
The islets are a compact collection of endocrine cells arranged in clusters and cords and are crisscrossed by a dense network of capillaries. The capillaries of the islets are lined by layers of [[endocrine]] cells in direct contact with vessels, and most endocrine cells are in direct contact with blood vessels, by either [[cytoplasm]]ic processes or by direct apposition. According to the volume ''The Body,'' by [[Alan E. Nourse]],<ref>''The Body,'' by [[Alan E. Nourse]], in the Time-Life Science Library Series (op. cit., p. 171.) </ref> the islets are "busily manufacturing their hormone and generally disregarding the pancreatic cells all around them, as though they were located in some completely different part of the body."
===Exocrine===
{{main|Exocrine pancreas}}
In contrast to the endocrine pancreas, which secretes hormones into the blood, the exocrine pancreas produces [[digestive enzyme]]s and an alkaline fluid, and secretes them into the [[small intestine]] through a system of [[exocrine duct]]s. Digestive enzymes include [[trypsin]], [[chymotrypsin]], [[pancreatic lipase]], and [[pancreatic amylase]], and are produced and secreted by [[acinar cell]]s of the exocrine pancreas. Specific cells that line the pancreatic ducts, called [[centroacinar cell]]s, secrete a [[bicarbonate]]- and [[salt]]-rich solution into the small intestine.<ref>{{cite book
| last = Maton
| first = Anthea
| authorlink =
| coauthors = Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright
| title = Human Biology and Health
| publisher = Prentice Hall
| date = 1993
| location = Englewood Cliffs, New Jersey, USA
| pages =
| url =
| doi =
| id =
| isbn = 0-13-981176-1}}</ref>
===Regulation===
The pancreas receives regulatory innervation via [[hormone]]s in the blood and through the [[autonomic nervous system]]. These two inputs regulate the secretory activity of the pancreas.
{| class="wikitable"
| '''[[Sympathetic nervous system|Sympathetic]]''' ([[adrenergic]]) || '''[[Parasympathetic]]''' ([[muscarinic]])
|-
| α2: decreases secretion from [[beta cell]]s, increases secretion from [[alpha cell]]s || M3<ref>{{cite journal |author=Verspohl EJ, Tacke R, Mutschler E, Lambrecht G |title=Muscarinic receptor subtypes in rat pancreatic islets: binding and functional studies |journal=Eur. J. Pharmacol. |volume=178 |issue=3 |pages=303–11 |year=1990 |pmid=2187704| doi = 10.1016/0014-2999(90)90109-J <!--Retrieved from CrossRef by DOI bot-->}}</ref> increases stimulation from [[alpha cell]]s and [[beta cell]]
|}
==Diseases of the pancreas==<!-- This section is linked from [[Pancreatic dysfunction]]. See [[WP:MOS#Section management]] -->
{{main|Pancreatic disease}}
Because the pancreas is a storage depot for digestive enzymes, injury to the pancreas is potentially very dangerous. A puncture of the pancreas generally requires prompt and experienced medical intervention.
==History==
The pancreas was first identified by [[Herophilus]] (335-280 BC), a [[Greeks|Greek]] [[anatomist]] and [[surgery|surgeon]]. Only a few hundred years later, [[Ruphos]], another Greek anatomist, gave the pancreas its name. The term "pancreas" is derived from the [[Greek language|Greek]] ''pan'', "all", and ''kreas'', "flesh", probably referring to the organ's homogeneous appearance.<ref>{{cite web |last=Harper |first=Douglas |title=Pancreas |work=Online Etymology Dictionary |url=http://www.etymonline.com/index.php?term=pancreas |accessdate=2007-04-04}}</ref>
==Embryological development==
[[Image:Suckale08FBS fig1 pancreas development.jpeg|thumbnail|300px|Schematic illustrating the development of the [[pancreas]] from a [[dorsal]] and a [[ventral]] bud. During maturation the ventral bud flips to the other side of the gut tube (arrow) where it typically fuses with the dorsal lobe. An additional ventral lobe which usually regress during development is omitted.]]
The pancreas forms from the embryonic [[foregut]] and is therefore of [[endoderm]]al origin. Pancreatic development begins the formation of a ventral and dorsal anlage (or buds). Each structure communicates with the foregut through a duct.
Differential rotation and fusion of the ventral and dorsal pancreatic buds results in the formation of the definitive pancreas.<ref name="carlson">{{cite book |author=Carlson, Bruce M. |title=Human embryology and developmental biology |publisher=Mosby |location=St. Louis |year=2004 |pages=pp372-4 |isbn=0-323-01487-9 |oclc= |doi=}}</ref> As the duodenum rotates to the right, it carries with it the ventral pancreatic bud and common bile duct. Upon reaching its final destination, the ventral pancreatic bud fuses with the much larger dorsal pancreatic bud. At this point of fusion, the main ducts of the ventral and dorsal pancreatic buds fuse, forming the [[duct of Wirsung]], the main pancreatic duct.
Differentiation of cells of the pancreas proceeds through two different pathways, corresponding to the dual endocrine and exocrine functions of the pancreas. In progenitor cells of the exocrine pancreas, important molecules that induce differentiation include [[follistatin]], [[fibroblast growth factor]]s, and activation of the [[Notch receptor]] system.<ref name="carlson"/> Development of the exocrine acini progresses through three successive stages. These include the predifferentiated, protodifferentiated, and differentiated stages, which correspond to undetectable, low, and high levels of digestive enzyme activity, respectively.
Progenitor cells of the endocrine pancreas arise from cells of the protodifferentiated stage of the exocrine pancreas.<ref name="carlson"/> Under the influence of [[neurogenin-3]] and [[Isl-1]], but in the absence of Notch receptor signaling, these cells differentiate to form two lines of committed endocrine precursor cells. The first line, under the direction of [[Pax-6]], forms α- and γ- cells, which produce the peptides [[glucagon]] and [[pancreatic polypeptide]], respectively. The second line, influenced by [[Pax-4]], produces β- and δ-cells, which secrete [[insulin]] and [[somatostatin]], respectively.
Insulin and glucagon can be detected in the fetal circulation by the fourth or fifth month of fetal development.<ref name="carlson"/>
==Additional images==
<gallery>
Image:Digestive system showing bile duct.png|Accessory digestive system.
Image:BauchOrgane wn.png|Digestive organs.
Image:Gray533.png|The celiac artery and its branches; the stomach has been raised and the peritoneum removed.
Image:Gray614.png|Lymphatics of stomach, etc. The stomach has been turned upward.
Image:Gray1097.png|Transverse section through the middle of the first lumbar vertebra, showing the relations of the pancreas.
Image:Gray1098.png|The duodenum and pancreas.
Image:Gray1100.png|The pancreatic duct.
Image:Gray1101.png|Pancreas of a human embryo of five weeks.
Image:Gray1102.png|Pancreas of a human embryo at end of sixth week.
Image:Gray1225.png|Front of abdomen, showing surface markings for duodenum, pancreas, and kidneys.
</gallery>
==References==
<references/>
{{Digestive glands}}
{{endocrine pancreas}}
* ''[http://www.britannica.com/eb/article-9058232/pancreas Pancreas entry in Britannica]''
[[Category:Abdomen]]
[[Category:Digestive system]]
[[Category:Endocrine system]]
[[Category:Diabetes]]
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[[uk:Підшлункова залоза]]
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