The pancreas is an organ of the glandular type and manifests itself in the digestive and endocrine systems. It isolates a number of enzymes involved in the process of splitting organic food structures. Actively involved in all types of metabolism.
Anatomy
This is an organ of oblong shape, whose length is about 20 cm. It occupies part of the retroperitoneal space, the lumbar spine is located behind, and the stomach is in front. Structural Parts:
- Head. Close contact with the horseshoe-shaped indentation formed by the bends of the duodenum allows the ducts of the pancreas to open in this section of the intestine and provide the digestive process with the necessary enzymes.
- Body. It has three faces and resembles a prism. At the border with the head there is a notch for the mesenteric vessels.
- Tail. Directed to the spleen.
The Wirsung duct runs along the axis of the organ. The organ is located in the connective tissue capsule. The front surface of the gland is covered with peritoneum.
Circulation
The organ receives arterial nutrition from the hepatic, gastroduodenal arteries. The caudal part is supplied from the arterial bed of the spleen. Venous blood departs from the organ into the portal vein.
Nervous support
Gets vegetative innervation. The tenth pair of cranial nerves provides parasympathetic nerve support, and the celiac and superior mesenteric ganglia have a sympathetic effect.
Physiology
The structure of the pancreas implies the performance of two functions.
Function of external (exocrine) secretion
The organ parenchyma forms pancreatic juice, which has an alkaline reaction to neutralize the acidic food lump. The volume of juice per day is up to 2 liters. The base of the juice is water, bicarbonates, potassium ions, sodium 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 trypsin activation.
They are proteolytic enzymes, that is, cleaving the protein together with carboxypeptidase.
Active enzymes:
- amylase - breaks down carbohydrates (starch), is also present in the oral cavity;
- lipase breaks down fats, partially broken into small droplets of bile;
- ribonuclease and deoxyribonuclease act on RNA and DNA.
The function of internal (endocrine) secretion
The structure of the pancreas implies the presence of separate 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. Hyperglycemia is produced in response.
- Alpha cells are responsible for the production of glucagon. Provides the release of glucose from the depot in the liver, which increases blood sugar. Synthesis activates a decrease in glucose levels, stress effects, excessive physical activity. It inhibits insulin production and hyperglycemia.
- Delta cells synthesize somatostatin, which inhibits the functioning of the gland.
- PP cells synthesize pancreatic polypeptide, which reduces the excretory function of the gland.
Pancreatic juice is released when:
- evacuation of the food lump into the duodenum;
- the production of cholecystokinin, secretin and acetylcholine;
- the work of the parasympathetic department of the nervous system.
Inhibition of pancreatic juice production contributes to:
- trypsin inhibitor production by pancreatic acini;
- inhibitory effect of glucagon, somatostatin, adrenaline;
- sympathetic influence.
Ducts
The figure shows that the pancreatic ducts open into the duodenum.
- Santorini duct (incremental).
- Small and large duodenal papillae.
- Wirsung duct.
The most important is the Wirsungs, it completely repeats the shape and bends of the gland and serves as a collector for interlobular tubules. The duct "tree" can be loose, that is, the tubules fall into the main one in large numbers (about 60) and penetrate the entire thickness of the gland. The trunk type has about 30 tubules and they are located at a greater distance from each other.
He became interested in the structural features of the main pancreatic duct by an anatomist from Germany, Virsung, who later received his name. Wirsung noted that the course of the duct completely repeats the shape of the pancreas. The source of the duct originates in the caudal 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 comes out through the intralobular ducts, and then they connect with the interlobular, forming the main one. The formed pancreatic ducts open in the descending part of the duodenum.
Later, the scientist Vater described in detail the large papilla of the duodenum and, like many scientists, called it by its name. The papilla is surrounded by the sphincter of Oddi. From the observations of Fater, it became clear that the papilla is a single hole (95% of cases) for pancreatic and common bile ducts. The study of cadaveric material showed that an additional small papilla may be present for the mouth of the extra duct. There is evidence that there is a special type of duct that occurs in 5% of cases. It begins in the thickness of the head, its migration is disturbed, and it ends with the Helly sphincter on the wall of the duodenum.
The
pancreatic ducts open into the duodenum, interacting with the biliary tract. The pathology of any of these anatomical structures often causes a violation of the function 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 broken and obstructive jaundice develops. Excrement of the gallbladder can migrate and clog the path of the gallbladder. Later they become inflamed and squeeze the main pancreatic. The situation leads to inflammation of the
Wirsung duct, the process goes to the parenchyma of the gland and inflammation of the gland develops (pancreatitis). The pathological interaction of the intestine and pancreas is the abandonment of intestinal contents at the mouth of the main duct, enzymes are activated, and the gland self-digests. The process is dangerous by the development of total necrosis in the organ and the death of the patient.
Violation of the patency of the ducts can be observed with congenital malformations. They can branch out unnecessarily and, as a rule, the daughter ducts are much narrower than normal. Stenosis makes it difficult to exit the juice, the gland overflows and becomes inflamed. The reverse side of the coin - the channels can expand pathologically 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.
Finally
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 treat pancreatic hormone deficiency. Pathological formations (cysts, tumors) in the gland are eliminated by surgeons.