The liver and pancreas (pancreatic) gland are the most important human organs. A person cannot live without a liver. They are the largest glands of the digestive system. The functions of the pancreas and liver are extremely diverse; liver cells (hepatocytes) perform about 500 functions. What role do digestive glands play in the body - the liver and pancreas? Are they only responsible for digestion?
Anatomical features of the liver and pancreas
What is the pancreas and liver?
The pancreas is the second largest organ of the digestive system. It is located behind the stomach, has an oblong shape. As an exocrine gland, it secrets pancreatic juice containing enzymes that digest carbohydrates, proteins and fats. Like the endocrine gland, the hormones insulin, glucagon and others secrete. 99% of the gland has a lobed structure - this is the exocrine part of the gland. The endocrine part occupies only 1% of the volume of the organ, is located in the tail of the gland in the form of islets of Langerhans.
The liver is the largest human organ. It is located in the right hypochondrium, has a lobed structure. Under the liver is the gall bladder, which stores bile produced in the liver. Behind the gallbladder are the gates of the liver. Through them, the portal vein enters the liver, carrying blood from the intestines, stomach and spleen, the hepatic artery that feeds the liver itself, nerves. Lymphatic vessels and the common hepatic duct exit the liver. The cystic duct from the gallbladder flows into the latter. The resulting common bile duct, together with the duct of the pancreatic gland, opens into the duodenum.
Pancreas and liver - glands, what secretion?
Depending on where the gland secretes its secretion, glands of external, internal and mixed secretion are distinguished.
- The endocrine glands produce hormones that enter directly into the bloodstream. Such glands include: the pituitary gland, thyroid gland, parathyroid gland, adrenal glands;
- The endocrine glands produce specific contents that are secreted onto the surface of the skin or into any cavity of the body, and then outward. These are sweat, sebaceous, lacrimal, salivary, mammary glands.
- Glands of mixed secretion produce both hormones and substances secreted from the body. They include the pancreas, gonads.
According to Internet sources, the liver is an external secretion gland, however, in the scientific literature, the question: “The liver is iron, what is secretion?”, Gives a definite answer - “Mixed”, because several hormones are synthesized in this organ.
The biological role of the liver and pancreas
These two organs are called the digestive glands. The role of the liver and pancreas in digestion is the digestion of fats. The pancreas, without the participation of the liver, digests carbohydrates and proteins. But the functions of the liver and pancreas are extremely diverse, some of which are in no way associated with the digestion of food.
Liver functions:
- Hormonal It synthesizes some hormones - an insulin-like growth factor, thrombopoietin, angiotensin and others.
- Depositing. Up to 0.6 l of blood is stored in the liver.
- Hematopoietic. The liver during intrauterine development is an organ of hematopoiesis.
- Excretory. It secretes bile, which prepares fats for digestion - emulsifies them, and also has a bactericidal effect.
- Barrier. Various toxic substances regularly enter the human body: drugs, paints, pesticides, intestinal microflora metabolism products are produced in the intestine. Blood flowing from the intestines and containing toxic substances does not go directly to the heart, and then spreads throughout the body, but enters the portal vein into the liver. Every third of a person’s blood passes through this organ every minute.
In the liver, the neutralization of foreign and toxic substances that have got into it occurs. The danger of such substances is that they react with proteins and lipids of cells, disrupting their structure. As a result, such proteins and lipids, and therefore cells, and tissues and organs, do not fulfill their functions.
The process of neutralization goes in two stages:
- Translation of water-insoluble toxic substances into soluble,
- The connection of the obtained soluble substances with glucuronic or sulfuric acid, glutathione with the formation of non-toxic substances that are excreted from the body.
Metabolic function of the liver
This internal organ is involved in the metabolism of proteins, fats and carbohydrates.
- Carbohydrate metabolism. Provides consistent blood glucose. After a meal, when a large amount of glucose enters the blood, its supply in the form of glycogen is created in the liver and muscles. In between meals, the body receives glucose due to the hydrolysis of glycogen.
- Protein metabolism. Amino acids that have just entered the body from the intestines are sent through the portal vein to the liver. Here, coagulation system proteins (prothrombin, fibrinogen), and blood plasma (all albumin, α- and β-globulins) are built from amino acids. Here, amino acids enter the deamination and transamination reactions necessary for the mutual transformations of amino acids, the synthesis of glucose and ketone bodies from amino acids. In the liver, toxic products of protein metabolism, mainly ammonia, which turns into urea, are neutralized.
- Fat metabolism. After a meal, fats and phospholipids are synthesized in the liver from fatty acids coming from the intestines; part of the fatty acids is oxidized with the formation of ketone bodies and the release of energy. Between meals, fatty acids enter the liver from adipose tissue, where they undergo β-oxidation with the release of energy. In the liver, ¾ of all cholesterol in the body is synthesized. Only ¼ of it comes with food.
Pancreatic function
What is the pancreas already considered, now find out what functions it performs?
- Digestive Pancreatic enzymes digest all the components of food - nucleic acids, fats, proteins, carbohydrates.
- Hormonal The pancreas secretes several hormones, including insulin and glucagon.
What is digestion?
Our body consists of almost 40 trillion cells. For the life of each of them needs energy. Cells die, building materials are needed to form new ones. The source of energy and building material is food. It enters the digestive tract, is broken down (digested) into individual molecules that are absorbed into the bloodstream in the intestine and spread throughout the body to each cell.
Digestion, that is, the breakdown of complex food substances - proteins, fats and carbohydrates, into small molecules (amino acids), higher fatty acids and glucose, respectively, proceeds under the action of enzymes. They are found in digestive juices - saliva, gastric, pancreatic and intestinal juices.
Carbohydrates begin to be digested already in the oral cavity, proteins begin to be digested in the stomach. Nevertheless, most of the breakdown reactions of carbohydrates, proteins, and all the breakdown reactions of lipids occur in the small intestine under the influence of pancreatic and intestinal enzymes.
Undigested parts of the food are excreted.
The role of the pancreas in digestion
The pancreas plays an exceptional role in digestion. What is the pancreas responsible for? It secretes enzymes that hydrolyze proteins, carbohydrates, fats and nucleic acids in the small intestine.
The role of the pancreas in the digestion of proteins
Proteins, or food polypeptides, begin to break down in the stomach under the action of the trypsin enzyme to oligopeptides, which enter the small intestine. Here, oligopeptides are affected by pancreatic juice enzymes - elastase, chymotrypsin, trypsin, carboxypeptidase A and B. The result of their joint work is the breakdown of oligopeptides to di- and tripeptides.
Digestion is completed by intestinal cell enzymes, under the influence of which short chains of di- and tripeptides are broken down into individual amino acids, which are small enough to penetrate the mucous membrane and intestines and then enter the bloodstream.
The role of the pancreas in the digestion of carbohydrates
Polysaccharide carbohydrates begin to be digested in the oral cavity under the action of the salivary α-amylase enzyme with the formation of large fragments - dextrins. In the small intestine, dextrins, under the influence of the pancreatic enzyme, pancreatic α-amylase, break down to disaccharides, maltose and isomaltose. These disaccharides, as well as those that came with food - sucrose and lactose, break down under the influence of intestinal juice enzymes to monosaccharides - glucose, fructose and galactose, and much more glucose is formed than other substances. Monosaccharides are absorbed into the intestinal cells, then enter the bloodstream and are carried throughout the body.
The role of the pancreas and liver in the digestion of fats
Fats, or triacylglycerols, begin to be digested in an adult only in the intestines (in children in the oral cavity). The breakdown of fats has one feature: they are insoluble in the aquatic environment of the intestine, therefore, they are collected in large drops. How do we wash dishes on which a thick layer of fat is frozen? We use detergents. They wash off fat, as they contain surface-active substances that break down a layer of fat into small droplets that are easily washed off with water. The function of surface active substances in the intestine is performed by bile produced by liver cells.
Bile emulsifies fats - breaks up large drops of fat into individual molecules that may be exposed to the pancreatic enzyme, pancreatic lipase. Thus, the functions of the liver and pancreas during lipid digestion are performed sequentially: preparation (emulsification) - splitting.
During the decomposition of triacylglycerols, monoacylglycerols and free fatty acids are formed. They form mixed micelles, which also include cholesterol, fat-soluble vitamins, and bile acids. Micelles are absorbed into the intestinal cells and then enter the bloodstream.
Pancreatic hormone function
In the pancreas, several hormones are formed - insulin and glucagon, which ensure a constant level of glucose in the blood, as well as lipocaine and others.
Glucose plays an exceptional role in the body. Glucose is necessary for every cell, because the reactions of its transformation lead to the generation of energy, without which the life of the cell is impossible.
What is the pancreas responsible for? Glucose from the blood into the cells enters with the participation of special carrier proteins of several types. One of these species carries glucose from the blood to the cells of muscle and adipose tissue. These proteins work only with the participation of the pancreatic hormone - insulin. Tissues in which glucose enters only with the participation of insulin are called insulin-dependent.
What hormone does the pancreas secrete after eating? After eating, insulin is secreted, which stimulates reactions leading to a decrease in blood glucose levels:
- the conversion of glucose into a storage carbohydrate - glycogen;
- glucose transformations that occur with the release of energy - glycolysis reactions;
- the conversion of glucose into fatty acids and fats are energy storage substances.
With insufficient amounts of insulin, diabetes mellitus occurs, accompanied by metabolic disorders of carbohydrates, fats and proteins.
What hormone does the pancreas secrete during fasting? 6 hours after eating, the digestion and absorption of all nutrients ends. Blood glucose levels begin to decline. It is time to use spare substances - glycogen and fats. Their mobilization is caused by the hormone of the pancreas - glucagon. Its production begins with a drop in blood glucose, its task is to increase this level. Glucagon stimulates reactions:
- conversion of glycogen to glucose;
- the conversion of amino acids, lactic acid and glycerol to glucose;
- fat breakdown.
The joint work of insulin and glucagon ensures the preservation of the level of glucose in the blood at a constant level.
What is pancreatitis and how to treat it?
In diseases of the liver and pancreas, the digestion of food components is impaired. The most common pancreatic pathology is pancreatitis. The disease develops in case of obstruction of the pancreatic duct. Enzymes produced in the iron and capable of digesting proteins, fats and carbohydrates do not enter the intestines. This leads to:
- enzymes begin to digest the organ itself, this is accompanied by severe pain in the abdomen;
- food is not digested, it leads to upset stools and severe weight loss.
They treat pancreatitis with drugs that suppress the production of enzymes by the gland. Proper nutrition for pancreatic pancreatitis is crucial. At the beginning of treatment, for a few days, they must prescribe complete fasting. The main rule of nutrition for pancreatic pancreatitis is to choose foods and a meal regimen that do not stimulate the production of enzymes by the gland. For this, a fractional intake of warm food is prescribed in small portions. Dishes are first selected carbohydrate, in semi-liquid form. Then, as the pain subsides, the diet is expanded, excluding fatty foods. It is known that the pancreas, subject to all recommendations, is completely restored one year after the start of treatment.
The functions of the liver and pancreas in the body are diverse. These two organs are of great importance in digestion, because they provide the digestion of proteins, fats and carbohydrates in food.