what is pancreas? its exocrine role along with role of islets of Langerhans and diseases related to pancreas


Pancreas is also one of the most important gland of human because it performs dual functions such as it performs role as an endocrine gland and as well as an exocrine gland. As an endocrine gland it is involved in production and release of various useful hormones such as insulin and glucagon whereas it plays its exocrine role in digestion of food at the level of duodenum of the small intestine by secreting pancreatic juice into the duodenum through the pancreatic duct. Pancreas in humans is also known ass heterocrine gland because of its dual function. In humans pancreas is present in the abdomen behind the stomach. Pancreas is about 6-8 inches long. The head of the pancreas is on the right side of the abdomen and is connected to the duodenum through the help of the pancreatic duct from which pancreas pours its pancreatic juice into the duodenum of the small intestine.The narrow end of the pancreas that also goes by the name of tail extends to the left side of the abdomen next to the spleen. 95% of the pancreas is based upon exocrine tissues. A healthy pancreas creates about 1 liter of these digestive enzymes every day. The remaining 5% of the cells of the pancreas are endocrine cells that are also known as the islets of Langerhans. These cells produces hormones that regulates pancreatic secretion and control blood sugar level. Presence has a color similar to that of salmon. Pancreas is divide into three regions that are head tail and body two main ducts of the pancreas are the pancreatic duct and a smaller accessory pancreatic duct that runs through the body of pancreas joining with the common bile duct near a small ballooning called ampulla of vater that is surrounded by a muscle that goes by the name of sphincter of oddi. The head of the pancreas wraps  around the superior mesenteric artery and vein from the back of the head region of the pancreas emerges a small structure  that goes by the name of uncinate process which extends to the back of the superior mesenteric vein and ends at the superior mesenteric artery. To form the portal vein the superior mesenteric artery passes down in front of the left half across the uncinate process and the superior mesenteric vein runs upwards on the right side of the artery and behind the neck joins with the lineal vein. The body is the largest part of the pancreas and mostly lies behind the stomach with its tip region near the top of the pancreas and the base at the bottom. The pancreas narrows towards the tail which sits next to spleen and sits between the layers of the ligament between the spleen and the left kidney. Pancreas has a rich blood supply the splenic artery runs along the margin of the pancreas and supplies the left part of the body and the tail through its pancreatic branches the supply of oxygenated blood to the head of the pancreas is given by superior and inferior pancreaticoduodenal surfaces whereas if we talk about the deoxygenated blood the body and the neck of the pancreas drains it deoxygenated blood into the splenic vein.

function of pancreas
During the time of embryonic development the pancreas forms as two buds from the foregut as an embryonic tube that is the precursor to the gastrointestinal tract. Pancreatic development begins with the formation of a dorsal and ventral pancreatic bud. The ventral pancreatic bud forms the head and uncinate process. The definitive pancreas results from the rotation of the ventral bud an fusion of the two buds. The ventral pancreatic bud fuses with the much larger dorsal pancreatic bud insulin and glucagon can be detected in the human fetal circulation by the fourth or fifth month of the fetal development.

function of pancreas
If we talk generally considering both endocrine and exocrine functions of the pancreas than we can say that its functions are blood sugar regulation and metabolism along with aiding in the digestion of food by sending pancreatic juice into duodenum of the small intestine and that pancreatic juice have enzymes in it that are responsible for the breakdown of protein lipids carbohydrates pancreas have its very major role in the release of glucose regulating hormones such as 
  • insulin
  • glucagon
  • amylin
  • somatostatin 
  • ghrelin
  • pancreatic polypeptide
so on the basis of functions and secretion we can divide roles of pancreas into two major types
  • endocrine role
  • exocrine role
exocrine role of pancreas
The exocrine tissues of the pancreas secretes a clear watery and alkaline juice that contains several enzymes such as trypsin amylase lipase and they are responsible for the breakdown of food into smaller molecules that can be easily taken up by the intestine this is the exocrine role of the pancreas. The cells that do this are arranged in clusters called acini. Secretion into the middle of the acinus accumulate in intralobular ducts which drains into the pancreatic duct which ultimately drains into the duodenum of the small intestine. Approximately 1.5 - 3 liters of this fluid is secreted in this manner every day enzymes of the pancreatic juice such as amylase trypsin and lipase are secretes in a fluid rich in bicarbonate. Alkaline pH is the most optimum for the enzymes that acts in the duodenum and also responsible for the neutralization of stomach acid that enters the duodenum.  Chyme after neutralization by secretions from liver pancreas and duodenum is called as chyle the main components of the pancreatic juice are as following 
  • amylase 
  • lipase
  • trypsin
  • chymotrypsin
  • sodium bicarbonate
secretion in this region is greatly influenced by hormones such as 
  1. secretin 
  2. cholecystokinin 
  3. vasoactive intestinal peptide
that are stimulated from the vagus nerve hormone gastrin is released from the stomach whereas the hormone secretin is released from the duodenum lining from S cells (that are found in duodenum and jejunum ) as a result of gastric acid or acidity that comes from the stomach and in the duodenum that acidity or gastric acid is neutralized such as conversion of chyme into chyle because intestine works in alkaline medium the hormone vasoactive intestinal peptide increases the secretion of enzymes and bicarbonate. Sodium bicarbonate is involved in neutralization chyme and provide alkaline medium. Secretin and vasoactive intestinal peptide acts to increase the opening of the cystic fibrosis trans-membrane conductance regulator which leads to more membrane depolarization and more secretion of bicarbonate. Such as in case of stomach when a layer of mucus and various other factors covers the internal lining of the stomach to prevent it being digested from the same enzyme pepsin that breakdown protein in stomach and stomach is also made of protein Similarly to ensure that the digestive action of the pancreas does not act such to digest the tissue of its own therefore the internal lining of the pancreas is also protected by releasing enzymes in inactive form along with the release of various  protecting factors such as trypsin inhibitor and the main chain of release and activation is such that trypsin is secreted in inactive form trypsinogen which is activated by enterokinase an enzymes which is secreted by the lining of the duodenum whereas the chymotrypsin is secreted in inactive form chymotrypsinogen which is actiavted by trypsin and also the low levels of calcium within the cells causes inactivation of trypsin.

endocrine role of pancreas

islets of Langerhans
The endocrine function of pancreas is the release of hormones such as insulin and glycogen. The endocrine cells of the pancreas are known as the islets of Langerhans. The islets of Langerhans constituents about 1-2 % of the pancreases and receives 10-15 % of the blood flow they have their most important role in the metabolism of the glucose each of the islets of Langerhans are separated from the surrounding pancreatic tissues by a thin fibrous connective tissue capsule. As endocrine glands do not have any ducts therefore they are also known as the ductless less glands therefore so they pour their secretion into blood similarly islets of Langerhans are the endocrine cells of the pancreas so they pour their hormones into the blood. Islets of Langerhans are made up of total five different kinds of cells and their hormonal secretion are as following 
  • alpha cells that produces glucagon 
  • beta cells that produces insulin and amylin 
  • delta cells that produces somatostatin 
  • pancreatic polypeptide cells/gamma cells/F cells produces pancreatic polypeptide 
cells of the islets of Langerhans can influence each other through paracrine and autocrine communications.The main endocrine function of the pancreas is the blood regulation. When blood glucose levels are low alpha cells secretes glycogen which increases blood glucose level and when the opposite happens such as when the blood glucose level is high beat cells secrets insulin to decrease the amount of glucose in the blood. Delta cells secretes somatostatin which decreases the release of insulin and glucose activity of the cells of insulin and glucose. Activity of the cells of the islets of Langerhans are also effected by the autonomic nervous system.

diseases related to pancreas
Some of the diseases related to pancreas are as following 
  • diabetes type 1 
  • diabetes type 2
  • pancreatitis
  • cystic fibrosis in pancreas
  • pancreatic pseudocyst
diabetes type 1 
                    diabetes type 1 is also known as insulin dependent diabetes mallitus it is also called as juvenile diabetes because it usually occurs in early age before 40 it arises due to deficiency of pancreatic hormone insulin that normally routes blood glucose to cells for the use it is autoimmune disorder the immune system backfires and manufactures auto antibodies against body's own cell sometimes specific viral infections activate autoimmune response T cells of immune system attack pancreas and destroy insulin producing beta cells diabetics patients suffering from type 1 diabetes must receive exogenous insulin to survive the insulin gene is located on short arm of chromosome 11 polymorphism and genetic variations within this locus are responsible for diabetes type 1 

diabetes type 2
                                        it is also called as non insulin dependent diabetes mellitus it accounts for 90% of all the diabetic patients it occurs among people over the age of 40 and is more common among the obese such person produces some endogenous insulin but their body cells gradually fail to respond to insulin and cannot take up glucose from blood thee develop a sort of insulin resistance as exercise reduces obesity it indirectly increases insulin sensitivity and improves glucose tolerance about 2-5 % of the type 2 diabetics get the disease early in life before 25 years of age and such a condition is known as the maturity onset diabetics of the young 

                  pancreatitis is also known as the inflammation of the pancreas it is mostly associated with gallstones or chronic alcohol use along with some of the other causes this condition is likely to cause intense pain in the abdomen that is associated with nausea and vomiting in pancreatitis enzymes of the exocrine pancreas damage the structure and the tissues of the of the pancreas when the digestive functions of the pancreas is affected this may lead to problems with the fat digestion and the development of steahorrhoea whereas when the endocrine function is effected it causes diabetes

pancreatic pseudocyst
                                    pancreatic pseudocyst is a circumscribed collection of fluid rich in pancreatic enzymes blood and necrotic tissues typically located in the lesser sac of the abdomen pancreatic pseudocyst are usually complications of pancreatitis although in children they frequently occur following abdominal trauma the major and main symptom of pancreatic pseudocyst includes abdominal discomfort and indigestion diagnosis of pancreatic pseudocyst can be based on cyst fluid analysis 

cystic fibrosis 
                      cystic fibrosis in pancreas also known as pancreatic fibrosis is a genetic condition that affect multiple body organs such as lungs pancreas etc pancreatic fibrosis is a characteristic feature of chronic pancreatitis the fibrosis develops as a result of abnormal activation of stromal cells and deposition of extracellular matrix pancreatic fibrosis impairs endocrine and exocrine functions of the pancreas digestive and diabetic problem may also arise from it.


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