The pancreas is a small gland located near the small intestine.
It is made up of two kinds of tissues that independently function as exocrine and endocrine glands.
As an exocrine organ, the pancreas secretes digestive enzymes into the duodenum.
Endocrine function of the pancreas
The primary products of the endocrine portion of the pancreas are glucagon and insulin, two non-steroid protein hormones.
These hormones regulate the body’s metabolism of glucose and other carbohydrate molecules. They are produced by the islets of Langerhans.
Insulin forces the body to store nutrients surplus to our immediate needs:
Insulin increases the intake of glucose, fatty acid, and amino acids by adipose (fat) and muscle cells and activates enzyme systems that convert glucose to glycogen in liver and muscle cells.
In addition, insulin stimulates protein synthesis and tissue growth throughout the body, and suppresses the metabolism of glucose in liver and muscle cells.
When insulin attaches to a receptor, the insulin-receptor combination migrates into the cell.
Part of the receptor molecule has enzymatic properties. Insulin activates these enzymes by attaching to the enzyme molecule.
These receptor enzymes then activate protein molecules (carriers) that transport glucose into the cell by facilitated diffusion.
Starvation (fasting) tends to induce the production of more receptors, while obesity decreases the number of cell receptors on cell surfaces.
Glucagon hormone secretion, which performs its functions as a catabolic hormone, triggers the cellular release of glucose, fatty acids, and amino acids into the bloodstream.
Homeostatic mechanisms for regulation of blood glucose levels
Diabetes is a malfunction of one of the major homeostatic systems in the body.
This system controls the levels of sugar (usually glucose) in the blood.
Normally, blood glucose level stays around 100 mg/mL, although it fluctuates somewhat during the day.
These changes of blood glucose levels are controlled by a homeostatic mechanism called antagonistic hormones (insulin vs. glucagon).
Insulin is a hormone that lowers blood sugar (glucose) levels.
It accomplishes this by making the cell membranes with which it comes in contact more permeable to glucose. In addition, insulin triggers changes within the cells to increase their rate of metabolism and thus consume increased amounts of glucose.
Glucagon raises blood glucose level by stimulating the breakdown of glycogen.
Rather than changing the chemistry of many of the body cells, this hormone targets a group of cells (found primarily in the liver) that store excess glucose in the form of glycogen.
While insulin and glucagon work together to maintain blood sugar at normal levels, they have opposite effects and are therefore antagonistic.
Type 1 Diabetes (juvenile diabetes)
Type 1 diabetes is an autoimmune disorder.
In the case of Type 1 diabetes, the immune system attacks the pancreas, because it no longer recognizes certain cells of the pancreas as being “self.”
Diabetes mellitus type 2
Type 2 is a more common form of diabetes, affecting six percent of the population.
It is also referred to as adult onset diabetes, as it typically occurs in adults over the age of 40.
Ninety percent of diabetics are Type 2.
In the cases of type 2 diabetes, while the body produces insulin, it is either in insufficient quantities or the body cells neither recognize nor respond to the insulin.
This form of diabetes is often successfully treated by means of changes in diet and exercise.
Both forms of diabetes can cause rapid weight loss, blindness, and/or circulatory disorders that may have serious consequences.
