Pancreas
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Pancreas
1: Head of pancreas
2: Uncinate process of pancreas
3: Pancreatic notch
4: Body of pancreas
5: Anterior surface of pancreas
6: Inferior surface of pancreas
7: Superior margin of pancreas
8: Anterior margin of pancreas
9: Inferior margin of pancreas
10: Omental tuber
11: Tail of pancreas
12: Duodenum
Gray's
subject #251 1199
Artery
inferior
pancreaticoduodenal artery,
superior
pancreaticoduodenal artery,
splenic artery
Vein
pancreaticoduodenal veins,
pancreatic veins
Nerve
pancreatic plexus, celiac
ganglia, vagus[1]
Precursor
MeSH
pancreatic buds
Pancreas
Dorlands/Elsevier Pancreas
The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both
an endocrine gland (producing several important hormones, including insulin, glucagon, and
somatostatin), as well as an exocrine gland, secreting pancreatic juice containing digestive
enzymes that pass to the small intestine. These enzymes help in the further breakdown of the
carbohydrates, protein, and fat in the chyme.
Contents
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1 Histology
2 Function
o 2.1 Endocrine
o 2.2 Exocrine
o 2.3 Regulation
3 Diseases of the pancreas
4 History
5 Embryological development
6 As food
7 Additional images
8 References
[edit] Histology
Under a microscope, stained sections of the pancreas reveal two different types of
parenchymal tissue.[2] Lightly staining clusters of cells are called islets of Langerhans, which
produce hormones that underlie the endocrine functions of the pancreas. Darker staining cells
form acini connected to ducts. Acinar cells belong to the exocrine pancreas and secrete
digestive enzymes into the gut via a system of ducts.
Structure
Appearance
Function
Islets of
Langerhans
Lightly staining, large,
spherical clusters
Hormone production and secretion
(endocrine pancreas)
Pancreatic acini
Darker staining, small, berry- Digestive enzyme production and secretion
like clusters
(exocrine pancreas)
[edit] Function
The pancreas is a dual-function gland, having features of both endocrine and exocrine glands.
[edit] Endocrine
Main article: Endocrine pancreas
The part of the pancreas with endocrine function is made up of approximately million[3] 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.[4]
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 cytoplasmic processes or by direct apposition. According to the
volume The Body, by Alan E. Nourse,[5] 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."
[edit] Exocrine
Main article: Exocrine pancreas
In contrast to the endocrine pancreas, which secretes hormones into the blood, the exocrine
pancreas produces digestive enzymes and an alkaline fluid, and secretes them into the small
intestine through a system of exocrine ducts in response to the small intestine hormones
secretin and cholecystokinin. Digestive enzymes include trypsin, chymotrypsin, pancreatic
lipase, and pancreatic amylase, and are produced and secreted by acinar cells of the exocrine
pancreas. Specific cells that line the pancreatic ducts, called centroacinar cells, secrete a
bicarbonate- and salt-rich solution into the small intestine.[6]
[edit] Regulation
The pancreas receives regulatory innervation via hormones in the blood and through the
autonomic nervous system. These two inputs regulate the secretory activity of the pancreas.
Sympathetic (adrenergic)
Parasympathetic (muscarinic)
α2: decreases secretion from beta cells, increases
secretion from alpha cells
M3[7] increases stimulation from alpha
cells and beta cell
[edit] Diseases of the pancreas
Main article: 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.
An incision into the pancreas is known as a pancreatotomy.
[edit] History
The pancreas was first identified by Herophilus (335-280 BC), a Greek anatomist and
surgeon. Only a few hundred years later, Ruphos, another Greek anatomist, gave the pancreas
its name. The term "pancreas" is derived from the Greek pan, "all", and kreas, "flesh",
probably referring to the organ's homogeneous appearance.[8]
[edit] Embryological development
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 endodermal origin.
Pancreatic development begins the formation of a ventral and dorsal anlage (or buds). Each
structure communicates with the foregut through a duct. The ventral pancreatic bud becomes
the head and unciate process, and comes from the hepatic diverticulum.
Differential rotation and fusion of the ventral and dorsal pancreatic buds results in the
formation of the definitive pancreas.[9] 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 factors, and activation of the Notch receptor system.[9]
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.[9] 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.[9]
[edit] As food
The pancreas of lamb, beef, and pork is prepared and eaten. Along with the thymus, pancreas
is considered a sweetbread.
[edit] Additional images
Accessory digestive
system.
Digestive organs.
The celiac artery and
its branches; the
stomach has been
Lymphatics of
stomach, etc. The
stomach has been
raised and the
peritoneum removed.
Transverse section
through the middle of
the first lumbar
vertebra, showing the
relations of the
pancreas.
The duodenum and
pancreas.
The pancreatic duct.
turned upward.
Pancreas of a human
embryo of five
weeks.
Front of abdomen,
Pancreas of a human
showing surface
embryo at end of sixth markings for
week.
duodenum, pancreas,
and kidneys.
[edit] References
1. ^ Physiology at MCG 6/6ch2/s6ch2_30
2. ^ Histology at BU 10404loa
3. ^ Hellman B, Gylfe E, Grapengiesser E, Dansk H, Salehi A (2007). "[Insulin oscillations-clinically important rhythm. Anti-diabetics should increase the pulsative component of the
insulin release]" (in Swedish). Lakartidningen 104 (32-33): 2236–9. PMID 17822201.
4. ^ BRS physiology 4th edition ,page 255-256, Linda S. Constanzo, Lippincott publishing
5. ^ The Body, by Alan E. Nourse, in the Time-Life Science Library Series (op. cit., p. 171.)
6. ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna
Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood
Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1. OCLC 32308337.
7. ^ Verspohl EJ, Tacke R, Mutschler E, Lambrecht G (1990). "Muscarinic receptor subtypes in
rat pancreatic islets: binding and functional studies". Eur. J. Pharmacol. 178 (3): 303–11.
doi:10.1016/0014-2999(90)90109-J. PMID 2187704.
8. ^ Harper, Douglas. "Pancreas". Online Etymology Dictionary.
http://www.etymonline.com/index.php?term=pancreas. Retrieved on 2007-04-04.
9. ^ a b c d Carlson, Bruce M. (2004). Human embryology and developmental biology. St. Louis:
Mosby. pp. 372–4. ISBN 0-323-01487-9.
v•d•e
Anatomy of torso, digestive system: accessory digestive glands
Liver
by region: Left lobe (Caudate lobe, Quadrate lobe) • Right lobe •
Transverse fissure of liver • Bare area of the liver
by function: Fibrous capsule of Glisson • Hepatocyte • Space of Disse •
Space of Mall • Kupffer cell • Liver sinusoid • Ito cell • Hepatic lobule
Biliary tract
intrahepatic: Bile canaliculus • Canals of Hering •
Interlobular bile ducts • Intrahepatic bile ducts • Left and
Bile ducts Right hepatic ducts
extrahepatic: Common hepatic duct • Cystic duct • Common
bile duct
Gallbladder by region: Body • Fundus • Neck
by region: Tail • Body • Neck • Head • Uncinate process
Pancreas
by function: Islets of Langerhans • Exocrine pancreas
ducts: Pancreatic duct • Accessory pancreatic duct
Common
Hepatopancreatic ampulla • Sphincter of Oddi
v•d•e
Endocrine system > Pancreas – Islets of Langerhans
A/B
Other

alpha cell (glucagon) • beta cell (insulin)
delta cell (somatostatin) • PP cell (pancreatic polypeptide) • epsilon cell (ghrelin)
Pancreas entry in Britannica
Retrieved from "http://en.wikipedia.org/wiki/Pancreas"
Categories: Pancreas
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