The pancreas is a glandular type organ and manifests itself in the digestive and endocrine systems. Allocates a number of enzymes involved in the process of splitting the organic structures of food. Actively involved in all types of metabolism.
Anatomy
This is an oblong-shaped organ, the length of which is about 20 cm. It occupies part of the retroperitoneal space, behind is the lumbar spine, and in front is the stomach. Structural parts:
- Head. Close contact with the horseshoe-shaped depression formed by the bends of the duodenum allows the pancreatic ducts to open into this section of the intestine and provide the digestive process with the necessary enzymes.
- Body. It has three faces and resembles a prism. On the border with the head there is a notch for the mesenteric vessels.
- Tail. Directed to the spleen.
Along the axis of the organ passesWirsunga duct. The organ is located in a connective tissue capsule. The anterior surface of the gland is covered by the peritoneum.
Circulation
The organ receives arterial nutrition from the hepatic, gastroduodenal arteries. The caudal part is supplied with blood from the arterial bed of the spleen. Venous blood drains from the organ into the portal vein.
Nervous supply
Receives autonomic innervation. Parasympathetic nerve supply is provided by the tenth pair of cranial nerves, and sympathetic influence is exerted by the celiac and superior mesenteric ganglia.
Physiology
The structure of the pancreas involves two functions.
Function of external (exocrine) secretion
The parenchyma of the organ forms pancreatic juice, which has an alkaline reaction in order to neutralize the acidic food bolus. The volume of juice per day is up to 2 liters. The basis of the juice is water, bicarbonates, potassium and sodium ions and enzymes.
Some enzymes are inactive because they are very aggressive. These enzymes include:
- trypsin, its inactive form is trypsinogen, which is activated by intestinal enterokinase;
- Chymotrypsin, which is formed from chymotrypsinogen by activation by trypsin.
They are proteolytic enzymes, that is, they break down protein together with carboxypeptidase.
Active Enzymes:
- amylase -breaks down carbohydrates (starch), also found in the mouth;
- lipase breaks down fats partially broken down into small droplets by bile;
- ribonuclease and deoxyribonuclease act on RNA and DNA.
Function of internal (endocrine) secretion
The structure of the pancreas implies the presence of individual islets of Langerhans, which occupy 1-2% of its parenchyma. A number of hormones are released:
- Beta cells synthesize insulin. It is the "key" for the entry of glucose into cells, stimulates fat synthesis, reduces its breakdown, and activates protein synthesis. Produced in response to hyperglycemia.
- Alpha cells are responsible for the production of glucagon. Ensures the release of glucose from the depot in the liver, which increases blood sugar. Synthesis activates a decrease in glucose levels, stress, excessive physical activity. Inhibits insulin production and hyperglycemia.
- Delta cells synthesize somatostatin, which has an inhibitory effect on the functioning of the gland.
- PP-cells synthesize a pancreatic polypeptide that reduces the excretory work of the gland.
Pancreatic juice is secreted when:
- evacuation of the food bolus into the duodenum;
- production of cholecystokinin, secretin and acetylcholine;
- work of the parasympathetic nervous system.
Inhibition of pancreatic juice production contributes to:
- production of trypsin inhibitor by pancreatic acini;
- inhibitory action of glucagon, somatostatin, adrenaline;
- sympathetic influence.
Products
The figure shows that the pancreatic ducts open into the duodenum.
- Santorini channel (additional).
- Small and large duodenal papilla.
- Wirsunga duct.
The most important is Virsungov, he completely repeats the shape and bends of the gland and serves as a collector for the interlobular tubules. The ductal "tree" can be scattered, that is, the tubules flow into the main one in large numbers (about 60) and penetrate the entire thickness of the gland. The main type has about 30 tubules and they are located at a greater distance from each other.
The anatomist from Germany Wirsung, who later received his name, became interested in the structural features of the main pancreatic duct. Wirsung noted that the course of the duct completely repeats the shape of the pancreas. The source of the duct originates in the tail part and has a small diameter. In the area of the body, the diameter becomes wider. At the level of the head, the duct bends slightly and merges with the common bile duct, having the largest diameter.
The formation of pancreatic secretion begins with small structures of the lobules of the organ - acini. The secret exits through the intralobular ducts, and then they connect with the interlobular ducts, forming the main one. The formed pancreatic ducts open into the descending part of the duodenum.
Later, the scientist Vater described in detail the major duodenal papilla and, like many scientists, named it after himself. The papilla is surrounded by the sphincter of Oddi. From Vater's observations, it became clear that the papilla is a single opening (95% of cases) for the pancreatic and common bile ducts. The study of cadaveric material showed that there may be an additional small papilla for the mouth of the accessory duct. There is evidence that there is a special type of duct that occurs in 5% of cases. It starts in the thickness of the head, its migration is disturbed and it ends with the Helly sphincter on the wall of the duodenum.
The ducts of the pancreas open into the duodenum, interacting with the biliary tract. The pathology of any of these anatomical structures often causes dysfunction of another organ. For example, a change in the structure of the pancreas (tumor, inflammation, cyst) can compress the common bile duct. The passage of bile is disturbed and obstructive jaundice develops. Gallbladder feces can migrate and block the bile ducts. Later they become inflamed and compress the main pancreatic. The situation leads to inflammation of the Wirsung duct, the process passes to the parenchyma of the gland and inflammation of the gland (pancreatitis) develops. The pathological interaction of the intestine and pancreas consists in the reflux of intestinal contents into the mouth of the main duct, enzymes are activated, and self-digestion of the gland occurs. The process is dangerous by the development of a totalnecrosis in the organ and death of the patient.
Impaired patency of the ducts can be observed in congenital malformations. They may branch excessively and, as a rule, the daughter ducts are much narrower than normal. Stenosis makes it difficult for the juice to flow out, the gland overflows and becomes inflamed. The reverse side of the coin is that the channels can pathologically expand with tumor growth, the presence of stones in the ducts, and a chronic inflammatory process in the gland. This situation leads to an exacerbation of diseases of the stomach, liver.
In conclusion
Knowledge of the anatomy and physiology of the organ is necessary for general practitioners (therapists) for the early appointment of a course of enzyme preparations in the treatment of acute and chronic pancreatitis. Endocrinologists deal with the treatment of hormonal deficiency of the pancreas. Pathological formations (cysts, tumors) in the gland are eliminated by surgeons.
