The Pancreas

2006-12-17T00:30:00.000-08:00

Pancreas

The pancreas is a long, flat gland tucked behind your stomach between the upper part of your small intestine (duodenum) and your spleen. It plays important roles in digestion and metabolism. The organ produces enzymes essential for digestion and secretes hormones that help control blood sugar levels.

Food Needs to be Digested:
Food consists of carbohydrates (e.g. starch), proteins (e.g. meat), and fat (e.g. butter), and digestion is not possible without the enzymes produced by the pancreas. The digestive portion that produces digestive enzymes is called the "exocrine pancreas". The hormone-producing portion is called the "endocrine pancreas".

The Exocrine Pancreas:
The pancreas makes a number of different enzymes each of which is responsible for breaking down the different types of food into small particles suitable for absorption. The enzymes are made in small glands within the pancreas and travel along increasingly large tubes until finally they reach the main pancreatic tube. This connects the gland to the first part of the bowel where food passes after it has gone through the stomach.

The enzymes are not active when they are first made within the pancreas (otherwise they would digest the pancreas as well) but when they pass into the bowel they are activated by the juices in the bowel. The main enzymes are called amylase (which digests carbohydrates), trypsin (which digests protein) and lipase (which digests fats). The bile, which comes from the liver, is also very important for the digestion of fat because it acts like a soap and breaks up the fat into minute droplets so that the pancreatic lipase can digest it.

The Endocrine Pancreas:
The hormone-producing portion of the pancreas is called the "endocrine pancreas". The hormones secreted by the endocrine pancreas are insulin, glucagon, and somatostatin. The cells that secrete insulin are called Islet of Langerhans cells, or more simply just "islet cells".

Their effects are:

insulin--lowers blood sugar;
glucagon--raises blood sugar;
somatostatin--inhibits release of a variety of hormones, including growth hormone, thyrotropin, corticotropin, insulin, glucagon, gastrin, secretin and renin.

These functions, both exocrine and endocrine, may be affected by pancreatitis, an inflammatory condition that occurs when digestive enzymes, instead of breaking down food in the small intestine, attack the pancreas itself.

Link to Pancreas: Wikopedia>Pancreas

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Pancreas
From Wikipedia, the free encyclopedia

Gray's subject #251 1199

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

Artery

Inferior pancreaticoduodenal artery,
Superior pancreaticoduodenal artery

Vein
Pancreaticoduodenal veins

Nerve
Pancreatic plexus,
celiac ganglia,
vagus[1]

Precursor pancreatic buds

MeSH Pancreas

Dorlands/Elsevier p_02/

The pancreas is a gland organ in the digestive and endocrine systems of vertebrates[2]. It is both exocrine (secreting pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including insulin, glucagon, and somatostatin).

Contents
1 Anatomy
1.1 Arteries and veins
1.2 Nerves
2 Function
2.1 Endocrine
2.2 Exocrine
3 Diseases of the pancreas
3.1 Diabetes mellitus
3.2 Benign tumours
3.3 Pancreatic cancer
3.4 Cystic fibrosis
3.5 Exocrine pancreatic insufficiency
3.6 Hemosuccus pancreaticus
3.7 Pancreatitis
3.8 Pancreatic pseudocyst
4 History
5 Pancreas as a food
6 Pop culture references
7 Additional images
8 References

Anatomy
In humans, the pancreas is a 15-25 cm (6-10 inch) elongated organ in the abdomen. One of the organs behind the abdominal cavity, it's located posterior to the stomach and in close association with the duodenum.

It is often described as having three regions: a head, body and tail.

The pancreatic head abuts the second part of the duodenum. The head of pancreas is flattened from before backward, and is lodged within the curve of the duodenum. Its upper border is overlapped by the superior part of the duodenum and its lower overlaps the horizontal part; its right and left borders overlap in front, and insinuate themselves behind, the descending and ascending parts of the duodenum respectively.
The body of the pancreas lies at the level of L2 on the spine. The body of pancreas is somewhat prismatic in shape, and has three surfaces: anterior, posterior, and inferior.
The tail of the pancreas extends towards the spleen.The pancreatic duct (also called the duct of Wirsung[3]) runs the length of the pancreas and empties into the second part of the duodenum at the ampulla of Vater. The common bile duct usually joins the pancreatic duct at or near this point. Many people also have a small accessory duct, the duct of Santorini, which extends from the main duct more upstream (towards the tail) to the duodenum, joining it more proximal than the ampulla of Vater.[3] The tail of the pancreas, located anatomically left near the hilum of the spleen, is not simply an antomical distinction. The tail is the only part of the pancreas which contains Pancreatic Polypeptide (PP) cells, which are responsible for secreting pancreatic polypeptide to coordinate exocrine and islet enzyme release. PP cells are found in the tail's periphery. Beta cells (insulin secretory) and delta cells (somatostatin secretory) are found in the central part of the tail as with the rest of the pancreas. The cells described above are located exclusively in the islet cells; their secretions reach exocrine portions of the pancreas via the capillary network surrounding the islet cell populations.

Arteries and veins
The pancreas is supplied arterially by the Pancreaticoduodenal arteries[4] and the splenic artery:

the splenic artery supplies the neck, body, and tail of the pancreas.
the superior mesenteric artery provides the inferior pancreaticoduodenal artery
the gastroduodenal artery provides the superior pancreaticoduodenal artery

Venous drainage is via the pancreaticoduodenal veins which end up in the portal vein. The splenic vein passes posterior to the pancreas but is said to not drain the pancreas itself. The portal vein is formed by the union of the superior mesenteric vein and splenic vein posterior to the neck of the pancreas. In some people (some books say 40% of people), the inferior mesenteric vein also joins with the splenic vein behind the pancreas (in others it simply joins with the superior mesenteric vein instead).

Nerves
The pancreas is innervated by the pancreatic plexus; a subdivision of the celiac plexus that accompanies pancreatic arteries.

Function
Under a microscope, when properly stained, it is easy to distinguish two different tissue types in the pancreas.[5] These regions correspond to the main pancreatic functions:

Appearance Region Function

light staining circles (islets of Langerhans)

endocrine pancreas
secretes hormones that regulate blood glucose levels

darker surrounding tissue

exocrine pancreas
produces enzymes that break down digestible foods

Endocrine
There are four main types of cells in the islets of Langerhans. They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion:

Name of cells..Endocrine product....% of islet cells..Representative function
beta cells........Insulin and Amylin...50-80%........... lower blood sugar
alpha cells......Glucagon...................15-20%............raise blood sugar
delta cells.......Somatostatin...............3-10%...... inhibit endocrine pancreas
PP cells...........Pancreatic polypeptide.....1%.........inhibit exocrine pancreas

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, in the Time-Life Science Library Series, 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." (op. cit., p. 171.)

Exocrine
There are two main types of exocrine pancreatic cells, responsible for two main classes of secretions:

Name of cells...........Exocrine secretion...Primary signal
Centroacinar cells...bicarbonate ions.......Secretin
Basophilic cells........digestive enzymes....CCK
................................(pancreatic amylase,
..................................Pancreatic lipase,
..................................chymotrypsinogen,
..................................trypsinogen, etc.)

Diseases of the pancreas
Due to the importance of its enzyme contents, injury to the pancreas is potentially very dangerous. A puncture of the pancreas generally requires prompt and experienced medical intervention.

Diseases associated with the pancreas include:

Diabetes mellitus
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia. All three forms of the disease are due to the inability of the beta cells of the pancreas to produce sufficient insulin.

Researchers at the Toronto Hospital for Sick Children injected capsaicin into NOD mice (Non-obese diabetic mice, a strain that is genetically predisposed to develop the equivalent of diabetes mellitus type 1) to kill the pancreatic sensory nerves. This treatment reduced the development of diabetes mellitus in these mice by 80%, suggesting a link between neuropeptides and the development of diabetes. When the researchers injected the pancreas of the diabetic mice with sensory neuropeptide (sP), they were cured of the diabetes for as long as 4 months. Also, insulin resistance (characteristic of diabetes mellitus type 2) was reduced.

Benign tumours
Like any other organ, the pancras is susceptible to the growth of benign tumors. Benign tumors do not invade neighboring tissues, do not cause metastases, and usually do not return after surgical removal.

Pancreatic cancer
Pancreatic cancer is a malignant tumour within the pancreatic gland. Its prognosis is generally regarded as poor. The different types of pancreatic cancers include:

Tumors of the centroacinar cells.

Pancreatic Exocrine Tumors. Examples include:

Pancreatic adenocarcinoma. It represents about 95% of all pancreatic tumors. 75%
to 96% of all pancreatic adenocarcinomas are ductal cell adenocarcinomas.
Other tumors of the exocrine pancreas, such as serous cystadenomas.

Pancreatic Endocrine Tumors (PET's), also known as Endocrine Pancreatic Tumors (EPT's), or Islet Cell Tumors. They are a type of Neuroendocrine tumors. PET's represent between 1 and 2% of all pancreatic tumors. Between 15 and 30% of all PET's are non-functioning, while 70 to 85% of them are functioning. Examples of functioning PET's include:

Gastrinoma, producing excessive gastrin and causing Zollinger-Ellison Syndrome (ZES)
Insulinoma, producing excessive insulin
Glucagonoma, producing excessive glucagon
Vasoactive intestinal peptideoma (VIPoma), producing excessive vasoactive intestinal peptide(VIP)
PPoma, producing excessive pancreatic polypeptide (often classed with non-functioning PETs)
Somatostatinoma, producing excessive somatostatin Watery diarrhea,
hypokalemia-achlorhydria (WDHA)
CRHoma, producing excessive corticotropin-releasing hormonse (CRH)
Calcitoninoma, producing excessive calcitonin
GHRHoma, producing excessive growth-hormone-releasing hormone (GHRH)
Neurotensinoma, producing excessive neurotensin
ACTHoma, producing excessive adrenocorticotropic hormone (ACTH)
GRFoma, producing excessive growth-hormone release factor (GRF)
Parathyroid hormone–related
peptide tumor

Cystic fibrosis
Cystic fibrosis, also known as mucoviscidosis, is a hereditary disease that affects the entire body, causing progressive disability and early death. There is no cure for cystic fibrosis, and most affected individuals die young from lung failure. Cystic fibrosis is caused by a mutation in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR). The product of this gene helps create sweat, digestive juices, and mucus. Although most people without CF have two working copies of the CFTR gene, only one is needed to prevent cystic fibrosis. Cystic fibrosis develops when neither gene works normally. Therefore, it is considered an autosomal recessive disease. The name cystic fibrosis refers to the characteristic 'fibrosis' (tissue scarring) and cyst formation within the pancreas. Cystic fibrosis causes irreversible damage to the pancreas, which often results in painful inflammation (pancreatitis).

Exocrine pancreatic insufficiency
Exocrine pancreatic insufficiency (EPI) is the inability to properly digest food due to a lack of digestive enzymes made by the pancreas. EPI is found in humans afflicted with cystic fibrosis. It is caused by a progressive loss of the pancreatic cells that make digestive enzymes. Chronic pancreatitis is the most common cause of EPI in humans. Loss of digestive enzymes leads to maldigestion and malabsorption of nutrients.

Hemosuccus pancreaticus
Hemosuccus pancreaticus, also known as pseudohematobilia or Wirsungorrhage, is a rare cause of hemorrhage in the gastrointestinal tract. It is caused by a bleeding source in the pancreas, pancreatic duct, or structures adjacent to the pancreas, such as the splenic artery, that bleed into the pancreatic duct. Patients with hemosuccus may develop symptoms of gastrointestinal hemorrhage, such as blood in the stools, maroon stools, or melena. They may also develop abdominal pain. Hemosuccus pancreaticus is associated with pancreatitis, pancreatic cancer and aneurysms of the splenic artery. Angiography may be used to treat hemosuccus pancreaticus, where the celiac axis is injected to determine the blood vessel that is bleeding, because embolization of the end vessel may terminate the hemorrhage. Alternatively, a distal pancreatectomy may be required to stop the hemorrhage.

Pancreatitis
Pancreatitis is inflammation of the pancreas. There are three forms of pancreatitis, which are different in causes and symptoms, and require different treatment:

Acute pancreatitis: A rapidly-onset inflammation of the pancreas.
Chronic pancreatitis: A long-standing inflammation of the pancreas.
Hereditary pancreatitis: A genetic abnormality that renders trypsinogen active within the pancreas, which in turn leads to digestion of the pancreas from the inside.
Pancreatic pseudocyst: A pancreatic pseudocyst is a circumscribed collection of fluid rich in amylase and other pancreatic enzymes, blood and necrotic tissue, typically located in the lesser sac.

History
The pancreas was discovered 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 homogenous appearance.[6]

Pancreas as a food
Pancreases (specifically calf and lamb pancreases) are used in some meals often going by the name stomach sweetbreads.[2]

Pop culture references
Heywood Banks, who performs regularly on the Bob & Tom Show, recorded a song titled "The Pancreas," composed of doggerel verses that rather accurately, if facetiously, decribe the function of the pancreas. The lyrics include "Let's all sing a tribute to the pancreas...hey pancreas, have a nice day!"

Satiric singer "Weird Al" Yankovic has recently produced a song titled "Pancreas." It includes many lyrics about the functions of the organ as well as the names of various chemicals it produces, concluding, "I love my pancreas!" The song can be found on his 2006 album "Straight Outta Lynwood." Or you can scroll up to find it here!

References
^ Physiology at MCG
^ a b New Standard Encyclopedia, 1988. Volume P Page 68
^ a b Cutler, Anne G., et al., eds. Stedman's Medical Dictionary. Baltimore: The William and Wilkins Company, 1976 ed.
^ Norman/Georgetown pancreas
^ Histology at BU 10404loa
^ Harper, Douglas. Pancreas. Online Etymology Dictionary. Retrieved on April 4, 2007.
v • d • eAnatomy of torso, digestive system: Digestive glands

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