Function Of The Pancreas - Diseases Of The Pancreas - Health Article

Function Of The Pancreas - Diseases Of The Pancreas

What is a pancreas?


The pancreas is a gland lying transversely in the upper abdomen organ in vertebrates. The digestive enzymes produced by it are released into the duodenum. It is therefore an exocrine gland (exocrine "outward tampering"; in this case in the digestive tract). These digestive enzymes break down proteins, carbohydrates and fats of the food in the intestine into absorbable from the intestinal mucosa (recordable) size. Moreover, in the pancreatic hormones are formed, which are transferred directly into the blood. Thus, it is simultaneously also an endocrine gland (endocrine "inward tampering"). The endocrine portion of the pancreas, the islets of Langerhans which are primarily responsible for the regulation of blood glucose levels (over the hormones insulin and glucagon), and of the digestive processes.

An inflammation of the pancreas (pancreatitis) performs the released digestive enzymes to self-digestion of the organ. In a slowing formation of digestive enzymes (exocrine pancreatic insufficiency), the food can not be sufficiently open-minded. The most common disorder of the endocrine portion of the Diabetes (diabetes mellitus).

Anatomy in humans


Location and Structure
The pancreas of man is about 16-20 cm long, 3-4 cm wide and 1-2 cm thick wedge-shaped organ. They weigh between 40 and 120 g. The institution is divided into lobules, which structure the surface characteristic.

The pancreas is located in the retroperitoneal space, ie behind the peritoneum, between the stomach, duodenum, spleen, liver and large blood vessels of the abdomen (aorta and inferior vena cava). It is hardly atemverschieblich, ie in contrast to other organs of the abdominal cavity (eg. As the liver), their position in inhalation and exhalation changed little.

Macroscopically There are three different sections of the pancreas: the pancreas head (head of the pancreas), the pancreatic body (body of the pancreas) and pancreatic tail (tail of the pancreas). The pancreatic head is covered by the duodenum and carries a downwardly directed hook extension (uncinate process). At the Pankreaseinkerbung (notch pancreas), the head goes into the pancreatic body to the left. At this notch also extend the superior mesenteric artery and the superior mesenteric vein. The pancreatic body crosses running horizontally at the level of the first to second lumbar spine. There the organ bulges slightly inward in the mesh bag, which is referred to as network boss (omental tuberosity). Finally, the triangular in cross-section pancreatic body runs without clear boundary from the pancreatic tail, which extends to the vascular pole of the spleen.

The approximately 2 mm wide duct of the pancreas (pancreatic duct, Wirsung-speed) flows together with the common bile duct (ductus choledochus) or close to that in the duodenum. This estuary is (major duodenal papilla or papilla of vater) a wart-like elevation. For some individuals, a second, smaller duct is present, the Accessory pancreatic duct (Santorini-speed), the then opens on the small Zwölffingerdarmwarze (minor duodenal papilla) in the duodenum.

Histology
The pancreas is both exocrine and endocrine gland. As an exocrine gland it produces digestive enzymes, as endocrine hormones (see also section function).

The exocrine part consists of thousands of loosely assembled lobules with a diameter of about 3 mm. Such lobules contains several, surrounded by secretion-producing cells gland ducts (acini). The digestive enzymes produced by these glands cells are released without loss of cell components (merocrine secretion) in the form of an aqueous (serous) secretion and forwarded via the acini and in some cases saved. The acini are surrounded by a basement membrane, which is supported by a fine network of reticular fibers. About three to five acini are connected to form a complex or "glands tree" and open via so-called switching pieces in a common corridor. The cells of these pieces are called switching centroacinar cells. The ducts unite and eventually becomes the main excretory ducts. In the exocrine portion of the pancreas lie between the acini and cells, which are called pancreatic stellate cells. They play a role especially during repair processes.

Blood supply and lymphatic drainage
The supply of the pancreas is via three major vessels: the upper pancreatic duodenal artery (Superior pancreaticoduodenal artery), the great pancreatic artery (Greater pancreatic artery) and the lower pancreatic duodenal artery (Inferior pancreaticoduodenal artery) branch out into smaller arteries, which in part connect with each other (anastomose).

The venous blood from the body and tail of the pancreas is of small pancreatic veins (venae pancreaticae) via the splenic vein (vena splenic) in the portal vein (portal vein) directed. The blood from the head of the pancreas passes via the pancreatic duodenal vein (vena pancreaticoduodenal) in the upper Gekrösevene (superior mesenteric vein) and then also in the portal vein.

The lymphatics of the pancreas pull in the lymphoidei nodes (lymph nodes.) Pancreatici and the lymph nodes. pancreaticoduodenales the superior et inferior. These are close to the pancreas and lead the lymph into the intestinal trunk on.

Innervation
The pancreas is how almost all internal organs, supplied by both parts of the autonomic nervous system (sympathetic and parasympathetic). The parasympathetic supply is provided by the vagus nerve. About the M3 receptor α- and β-cells are stimulated. Sympathetic fibers reach over the Thoracic splanchnic nerves, the celiac ganglion, where they are switched to the second sympathetic neuron, which then moves into the pancreas. About α2-adrenoceptors secretion of β- and δ-cells is decreased and increased the α-cells. About β2-adrenoceptors secretion of β- and δ-cells is increased.

What is the function of the pancreas?


Function as an exocrine gland
As an exocrine gland, the pancreas is a pure serous gland and the most important digestive gland. It produces in humans a daily basis up to 2 l secretion in horses up to 35 l. The formation of the digestive secretion (also called pancreatic juice) is stimulated by the smell and taste of food and mastication on the vagus nerve. The stretching of the stomach wall (also via the vagus nerve), and from the hormones secretin and cholecystokinin enhance the formation and release of pancreatic juice.

The pancreatic secretion contains the precursors of proteolytic enzymes (trypsinogen, chymotrypsinogen, Procarboxypeptidasen, proelastase), the starch-digesting enzyme α-amylase, ribo- and deoxyribonucleases and serving fat-splitting enzymes (lipases). The proteolytic enzymes are in the production in the gland in an inactive form to prevent self digestion of the organ. The trypsinogen is converted only through targeted cleavage by the enzyme enteropeptidase the brush border of the duodenal mucosa in trypsin and thus effective. Trypsin in turn activates the other proteolytic enzymes. The lipase is active only by the protein colipase. The latter also comes as a precursor of the pancreas and is only activated by trypsin. Regarding the enzyme composition of the pancreatic juice, there are dietary tierartliche differences. So the pancreas forms in animals with low starch content in the diet, such as pure carnivores such as cats or herbivores such as horses and ruminants, hardly starch-digesting amylase. In monogastric species varies depending on the composition of the food after a few days and the enzyme pattern of the pancreatic juice.

In addition to the enzymes form the epithelial cells of the pancreatic ducts abundant bicarbonate ions (HCO3-), which increase the pH of the pancreatic juice to 8. The alkaline pancreatic juice neutralizes the acidified by the gastric juice, intestinal contents and thus creates an optimal environment for the digestive enzymes.

Function as an endocrine gland
In addition to this function, exocrine glands are endocrine glands of proportion, given the islets of Langerhans, hormones directly into the blood. In the α-cells is glucagon, pancreatic polypeptide and the ε-cells synthesized ghrelin in the β-cell insulin, in the δ-cell somatostatin, the PP-cells.

The stimulus for insulin secretion is the rise in blood sugar. There is further stimulation of the parasympathetic nervous system and some intestinal hormones (gastrin, secretin, GIP and GLP-1 cholecystokinin). By insulin, the blood sugar is lowered to a physiological level by dextrose (glucose) is absorbed in liver, skeletal muscle and adipose tissue. In addition, the glucose storage are promoted and inhibited glucose formation. In strong blood sugar waste is released from the α-cell glucagon, which results in the release of glucose from the liver and thus to a rise in blood sugar.

Somatostatin is the inhibition of the exocrine part and the α-cells. In high concentrations it also inhibits the β-cells. The function of the pancreatic polypeptide has not yet been sufficiently clarified, it presumably inhibits the appetite.

In addition to the classic five hormones a variety of other peptides of the islet cells formed, such as cholecystokinin, calcitonin gene-related peptide, insulin-like growth factors, peptide YY, Cocaine and amphetamine regulated transcript and Thyrotropin-releasing hormone in frogs and secretin.

Pancreas diseases


Diseases of the exocrine part
An acute inflammation of the pancreas (pancreatitis) causing severe pain in the upper abdomen ("belly rubber"), nausea, vomiting, constipation and fever. The most common cause of acute pancreatitis in humans are gallstones, for it is the chronic alcohol abuse. A traumatic Pancreatic may cause pancreatitis. In acute pancreatitis, Pancreatic it comes to self-digestion of the institution by released enzymes and thereby a strong inflammatory response.

The insufficient education of pancreatic enzymes are called exocrine pancreatic insufficiency. It can be purchased by loss of pancreatic tissue in chronic pancreatitis or pancreatic cancer, but also by genetic disorders like cystic fibrosis be inherited. The exocrine pancreatic insufficiency leads to digestive problems with large-volume fat chair and is treated by administration of pancreatin with meals.

Pancreatic cysts and -pseudozysten, bubble-like formations in the pancreas may arise as a developmental disorder caused by trauma, inflammation or tumors. Pancreatic cysts often cause no symptoms. Pseudocysts have no epithelial lining and usually develop after a pancreatitis by Gewebseinschmelzung. They may be associated with signs of inflammation such as fever and tend to abscess formation and other complications.

Pancreatic tumors in 98% of cases involve the exocrine portion. In the majority, there are malignant adenocarcinomas (ductal adenocarcinoma), which are feared because of their high mortality rate.

Several parasites attack the duct system of the pancreas. The pancreatic fluke (Eurytrema pancreaticum) occurs mainly in artiodactyls in East Asia and South America, the raccoon pancreatic fluke (Eurytrema procyonis) occurs in the United States of America and infects raccoons, rarely cats, and Lyperosomum intermedium also occurs in the United States on and infects rice rats.

Diseases of the endocrine portion of the pancreas
The most common disorder of the endocrine portion is diabetes (diabetes mellitus pankreopriver). It is a cosmopolitan mass disease with considerable economic importance. Worldwide suffer approximately 380 million people (8.3% of the population) from this disease. In diabetes mellitus there is an absolute or relative insulin deficiency or attenuated activity of insulin. About 5 to 10% of diabetes is caused by a disorder of the pancreas. Even in domestic dogs and cats is diabetes mellitus one of the most common endocrine diseases.
In hereditary nesidioblastosis of the islet cell tissue is increased and increased insulin secretion, which already leads to severe hypoglycemia in infants.
Endocrine tumors account for only about 2% of pancreatic tumors. Here outweigh tumors of the insulin-producing β-cells (insulinoma) and tumors that produce gastrin (Zollinger-Ellison syndrome). An accumulation of endocrine pancreatic tumors occurs when Wermer syndrome.

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