The pancreas is a digestive and an endocrine organ with both endocrine and exocrine functions. It is about six inches long located in the upper portion of the abdominal cavity. The head of the pancreas lies within the indentation of the duodenum and is connected to it by the pancreatic duct. The uncinate process extends from the head and the neck connects to the body of the pancreas, which lies directly behind the stomach. The tail of the pancreas extends to the left side of the body and is in contact with the spleen. The head receives its blood supply from the superior pancreaticoduodenal and mesenteric arteries, while the splenic artery supplies blood to the neck, body and tail.
The endocrine portion of the pancreas, which makes up about one percent of the total cell population, has specialized hormone-producing cells called Islets of Langerhans. Within the Islets are four main types of cells: alpha cells secrete glucagons, beta cells secrete insulin, delta cells secrete somatostatin, and gamma cells secrete pancreatic polypeptide. Insulin lowers blood sugar levels by converting glucose to glycogen, while glucagon raises the blood sugar levels by influencing liver cells to convert glycogen back to glucose.
The exocrine portion of the pancreas, which makes up the remaining 99 percent of the cell population, has acinar cells, which are specialized cells controlled by the autonomic nervous system that produce pancreatic juices and digestive enzymes. This contains buffers as well as many digestive enzymes, including: proteases, which break down proteins; pancreatic amylase, which breaks down large carbohydrates; pancreatic lipase, which breaks down lipids; and nuclease, which breaks down DNA and RNA. The pancreatic juice is secreted into the pancreatic duct which connects directly to the small intestine.
Pancreatic activity is directly regulated by the hormones in the blood on the islets of Langerhans and indirectly regulated by the autonomic nervous system. The sympathetic or adrenergic produces alpha2, which increases secretion from alpha cells and decreases secretion from beta cells; and beta2, which increases secretion from beta cells. The parasympathetic or muscarinic produces M3, which increases stimulation of alpha cells and beta cells.
Pancreatitis is a common problem resulting from inflammation of the pancreas. While the cause is often unknown, as the inflammation worsens, it becomes damaged by its own digestive chemicals and can ultimately cause tissue death. Pancreatitis can lead to other conditions, such as a pancreatic pseudocyst, which is a fluid-filled sac that may need to be surgically drained. Pancreatic cancer occurs when one of the many types of cells found in the pancreas gives rise to a tumor. It is often a life-threatening condition, mainly because the patient is usually asymptomatic until it is advanced. The most common type comes from the cells that line the pancreatic duct.
Diabetes Mellitus is an endocrine disorder characterized by noticeably high blood glucose levels. It can be caused by a genetic disorder, a virus, or generalized obesity. There are two types of Diabetes Mellitus: Type I and Type II. Type I is caused when the body is not able to produce enough insulin due to a loss of pancreatic Beta cells. This is usually a type of autoimmune disorder and is considered insulin dependent. It is generally diagnosed during childhood or adolescence and can be controlled by insulin injections and dietary changes. Type II is caused when the cells are unresponsive to glucose intake, which may be due to a reduced number of insulin receptors or by chronic excessive intake of glucose. It is generally diagnosed in overweight adults but has recently been diagnosed in children as well.
Image Credit: Cradel/Wikipedia