Pancreas

[3][4][5][6] As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin and pancreatic polypeptide.

The pancreas stretches from the inner curvature of the duodenum, where the head surrounds two blood vessels: the superior mesenteric artery and vein.

[7] The superior and inferior pancreaticoduodenal arteries run along the back and front surfaces of the head of the pancreas adjacent to the duodenum.

The cells of each acinus secrete inactive digestive enzymes called zymogens into the small intercalated ducts which they surround.

In each acinus, the cells are pyramid-shaped and situated around the intercalated ducts, with the nuclei resting on the basement membrane, a large endoplasmic reticulum, and a number of zymogen granules visible within the cytoplasm.

[16] The pancreas forms during development from two buds that arise from the duodenal part of the foregut, an embryonic tube that is a precursor to the gastrointestinal tract.

These are the predifferentiated, protodifferentiated, and differentiated stages, which correspond to undetectable, low, and high levels of digestive enzyme activity, respectively.

[17] The pancreas is involved in blood sugar control and metabolism within the body, and also in the secretion of substances (collectively pancreatic juice) that help digestion.

These are divided into an "endocrine" role, relating to the secretion of insulin and other substances within pancreatic islets that help control blood sugar levels and metabolism within the body, and an "exocrine" role, relating to the secretion of enzymes involved in digesting substances in the digestive tract.

[18] Insulin acts to decrease blood glucose levels by facilitating uptake by cells (particularly skeletal muscle), and promoting its use in the creation of proteins, fats and carbohydrates.

It does this by secreting a fluid that contains digestive enzymes into the duodenum, the first part of the small intestine that receives food from the stomach.

[21] Secretion is influenced by hormones including secretin, cholecystokinin, and VIP, as well as acetylcholine stimulation from the vagus nerve.

Secretin is released from the S cells which form part of the lining of the duodenum in response to stimulation by gastric acid.

Cholecystokinin is released from Ito cells of the lining of the duodenum and jejunum mostly in response to long chain fatty acids, and increases the effects of secretin.

Secretin and VIP act to increase the opening of the cystic fibrosis transmembrane conductance regulator, which leads to more membrane depolarisation and more secretion of bicarbonate.

Enterochromaffin cells of the pancreas secrete the hormones motilin, serotonin, and substance P.[9] It has been demonstrated that pancreatic tissue is a strong accumulator and secretor in the intestine of radioactive cesium (Cs-137).

Acute pancreatitis is likely to cause intense pain in the central abdomen, that often radiates to the back, and may be associated with nausea or vomiting.

Severe pancreatitis may lead to bleeding or perforation of the pancreas resulting in shock or a systemic inflammatory response syndrome, bruising of the flanks or the region around the belly button.

Detection of some of these enzymes, such as amylase and lipase in the blood, along with symptoms and findings on medical imaging such as ultrasound or a CT scan, are often used to indicate that a person has pancreatitis.

This may include removal of gallstones, lowering of blood triglyceride or glucose levels, the use of corticosteroids for autoimmune pancreatitis, and the cessation of any medication triggers.

[27] Symptoms tend to arise late in the course of the cancer, when it causes abdominal pain, weight loss, or yellowing of the skin (jaundice).

[27] Pancreatic cancer is usually diagnosed by medical imaging in the form of an ultrasound or CT scan with contrast enhancement.

This may include management of itch, a choledochojejunostomy or the insertion of stents with ERCP to facilitate the drainage of bile, and medications to help control pain.

However the incidence of these cancers has been rising sharply; it is not clear to what extent this reflects increased detection, especially through medical imaging, of tumors that would be very slow to develop.

[37] Diabetes mellitus type 1 is a chronic autoimmune disease in which the immune system attacks the insulin-secreting beta cells of the pancreas.

[38] The management of type 2 diabetes involves a combination of lifestyle measures, medications if required and potentially insulin.

Even when a single pancreas is present, two or three pancreatic ducts may persist, each draining separately into the duodenum (or equivalent part of the foregut).

[48] In teleost fish, and a few other species (such as rabbits), there is no discrete pancreas at all, with pancreatic tissue being distributed diffusely across the mesentery and even within other nearby organs, such as the liver or spleen.

In a few teleost species, the endocrine tissue has fused to form a distinct gland within the abdominal cavity, but otherwise it is distributed among the exocrine components.

The most primitive arrangement, however, appears to be that of lampreys and lungfish, in which pancreatic tissue is found as a number of discrete nodules within the wall of the gut itself, with the exocrine portions being little different from other glandular structures of the intestine.

The pancreas (shown here in pink) sits behind the stomach , with the body near the curvature of the duodenum , and the tail stretching to touch the spleen .
This image shows a pancreatic islet when pancreatic tissue is stained and viewed under a microscope. Parts of the digestive ("exocrine") pancreas can be seen around the islet, more darkly. These contain hazy dark purple granules of inactive digestive enzymes ( zymogens ).
A pancreatic islet that uses fluorescent antibodies to show the location of different cell types in the pancreatic islet. Antibodies against glucagon, secreted by alpha cells, show their peripheral position. Antibodies against insulin, secreted by beta cells, show the more widespread and central position that these cells tend to have. [ 9 ]
The pancreas originates from the foregut , a precursor tube to part of the digestive tract , as a dorsal and ventral bud. As it develops, the ventral bud rotates to the other side and the two buds fuse together.
The pancreas maintains constant blood glucose levels (shown as the waving line). When the blood glucose level is too high, the pancreas secretes insulin and when the level is too low, the pancreas secretes glucagon.
The pancreas has a role in digestion, highlighted here. Ducts in the pancreas (green) conduct digestive enzymes into the duodenum. This image also shows a pancreatic islet , part of the endocrine pancreas, which contains cells responsible for secretion of insulin and glucagon .
Pancreatic cancer, shown here, most commonly occurs as an adenocarcinoma in the head of the pancreas. Because symptoms (such as skin yellowing, pain, or itch) do not occur until later in the disease, it often presents at a later stage and has limited treatment options.
Relative incidences of various pancreatic neoplasms , with pancreatic cancers in red/pink color. [ 28 ]