Pancreas

A long, thin organ in humans, the pancreas has both digestive and endocrine functions and for this reason contains two completely different types of cells. Measuring about 12-15 cm (5-6 in) long. It is nestled within the curve of the duodenum and stretches transversely across the posterior abdomen behind the stomach, in front of the spine and aorta.

The digestive, or exocrine, cells of the pancreas consist of a number of small lobules, or acinar cells, joined together into small ducts that, in turn, join the two major ducts of Santorini and Wirsung, which empty through small muscular openings into the duodenum. The lobules contain numerous cells that secrete pancreatic secretions containing electrolytes and three important digestive enzymes, typsin, amylase, and lipase. These enzyme digest proteins, split fat, break down highly polymerized nucleic acids, and break down polysaccharides such as starch, amylopectin, and glycogen. The protein splitting enzyme enterokinase is mixed with it, or in the presence of diseases such as pancreatitis or cancer. In a similar manner the activity of the other enzymes is enhanced by the admixture of intestinal secretion and bile.

The endocrine function of the pancreas is to release homones secreted by small groups of cells called the islets of Langehans into the blood. The hormones secretin controls the amount of fluid secretion. The hormones pancreozymin and gastrin, as well as the vagus nerve, control the amount secreted. The islets of Langerhands secrete two hormones that regulat carbohydrate metabolisms. Insulin causes a decrease in blood sugar, glucagons increases blood sugar. Other hormones control intestinal motility or interact with the thyroid, adrenal, or pituitary glands. In the absence of these islet cells a person develops Diabetes Melitus.

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