The pancreas is a mixed secretions gland. As exocrine digestive gland it produces enzymes and releases them into the duodenum. And as endocrine gland

Pancreas

The pancreas is a mixed secretions gland. As exocrine digestive gland it produces enzymes and releases them into the duodenum. And as endocrine gland it produces and releases into the blood insulin and glucagon — hormones that regulate the metabolism of carbohydrates. Production of hormones is provided by pancreatic islet cells (islets of Langerhans) (diagram 163).

The main control factor of pancreatic hormones production is the glucose concentration in the blood. Its increasing enhances insulin production, decreasing — glucagon.

Insulin

Insulin promotes the reduction of blood glucose levels by increasing the cell membrane permeability thereto. Glucose — the main source of energy supply of the body and the only source for the brain. Therefore its concentration in the blood is maintained at a constant level in the range of 0.8-1.1 g/l. Excess of glucose that occurs as a result of its absorption from the intestinal tract, under the action of insulin is converted into glycogen — animal starch. Its main mass is accumulated in the liver.

Reducing glucose concentration below 0.5 g/l lead to disorders of the nervous system begins hypoglycemic coma, and death. This state may be normalized by intravenous infusion of glucose. Increasing glucose concentrations above 1.8 g/l (hyperglycemia) lead to its loss with the urine; a higher concentration may also cause coma by increasing the osmotic pressure of blood. Taken from http://worldofschool.org

Diagram 163. The structure of the pancreatic tissue: 1 — duct; 2 — digestive gland; 3 — alpha cells; 4 — islet of Langerhans; 5 — the beta cells; 6 — delta cells

Violation of insulin production leads to the development of diabetes. He was known even to the ancient Greeks and Romans. These patients experienced fatigue, drank plenty of water. Until the XX century diagnosis “diabetes” meant a death sentence. Today, millions of people suffer from this disease, but due to daily injection of insulin, they can live and work. Insulin is obtained from the pancreatic glands of animals.

Increased thirst, frequent urination, ulcers on the body may be signs of diabetes.

Glucagon

Glucagon promotes conversion of glycogen to glucose, causing its level growth in blood. Similarly, adrenaline influences the concentration of sugar in blood.

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Questions:
  • Identify the relationship of the pancreas structure and functions.

  • Why the pancreas glands are of a mixed secretion?