The liver and pancreas (pancreatic) gland are the most important human organs. A person cannot live without a liver. They are the largest glands in the digestive system. The functions of the pancreas and liver are extremely diverse; liver cells (hepatocytes) perform about 500 functions. What role do the digestive glands - the liver and pancreas - play in the body? Are they only responsible for digestion?
Anatomical features of the liver and pancreas
What are 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 secretes pancreatic juice containing enzymes that digest carbohydrates, proteins and fats. As an endocrine gland, it secretes the hormones insulin, glucagon, and others. 99% of the gland has a lobular 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 formislets of Langerhans.
The liver is the largest human organ. It is located in the right hypochondrium, has a lobed structure. Beneath the liver is the gallbladder, which stores the bile produced by the liver. Behind the gallbladder is the gate of the liver. Through them, the portal vein enters the liver, carrying blood from the intestines, stomach and spleen, the hepatic artery, which feeds the liver itself, and nerves. Lymphatic vessels and the common hepatic duct exit the liver. The cystic duct flows into the latter from the gallbladder. The resulting common bile duct, together with the duct of the pancreatic gland, opens into the duodenum.
Pancreas and liver are glands, what secretion?
Depending on where the gland secretes its secret, there are glands of external, internal and mixed secretion.
- The endocrine glands produce hormones that go directly into the blood. These glands include: pituitary gland, thyroid gland, parathyroid gland, adrenal glands;
- External secretion glands produce specific contents that are released onto the surface of the skin or into any cavity of the body, and then out. These are sweat, sebaceous, lacrimal, salivary, mammary glands.
- Glands of mixed secretion produce both hormones and substances excreted from the body. These include the pancreas, sex glands.
The liver, according to Internet sources, is an external secretion gland, but scientificallyliterature on the question: "Liver - gland, what secretion?", An unequivocal answer is given - "Mixed", since 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 to digest 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 have nothing to do with the digestion of food.
Liver Functions:
- Hormonal. Some hormones are synthesized in it - insulin-like growth factor, thrombopoietin, angiotensin and others.
- Depositing. The liver stores up to 0.6 liters of blood.
- Hematopoietic. The liver during fetal development is a hematopoietic organ.
- 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, metabolic products of the intestinal microflora are produced in the intestines. The 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 liver through the portal vein. A third of all human blood passes through this organ every minute.
In the liver, foreign and toxic substances that have entered it are detoxified. The danger of such substances is that theyreact with proteins and lipids of cells, disrupting their structure. As a result, such proteins and lipids, and hence cells, tissues and organs, do not perform their functions.
The process of neutralization is in two stages:
- Transfer of water-insoluble toxic substances into soluble ones,
- Combining the obtained soluble substances with glucuronic or sulfuric acid, glutathione to form 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 a constant content of glucose in the blood. After eating, when a large amount of glucose enters the bloodstream, its store in the form of glycogen is created in the liver and muscles. Between meals, the body receives glucose through 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, proteins of the coagulation system (prothrombin, fibrinogen), blood plasma (all albumins, α- and β-globulins) are built from amino acids. Here, amino acids enter into the reactions of deamination and transamination necessary for the mutual transformations of amino acids, the synthesis of glucose and ketone bodies from amino acids. The liver neutralizes toxic products of protein metabolism, mainly ammonia, which turns into urea.
- Fat metabolism. After eating, fats and phospholipids are synthesized in the liver from fatty acids coming from the intestines; partfatty acids are oxidized to form ketone bodies and release energy. Between meals, fatty acids from adipose tissue enter the liver, where they undergo β-oxidation with the release of energy. The liver synthesizes ¾ of all cholesterol in the body. Only ¼ of it comes from food.
Pancreas functions
What is the pancreas has already been considered, now let's find out what functions it performs?
- Digestive. Pancreatic enzymes digest all food components - nucleic acids, fats, proteins, carbohydrates.
- Hormonal. The pancreas secretes several hormones, including insulin and glucagon.
What is digestion?
Our body is made up of nearly 40 trillion cells. Each of them needs energy to live. Cells die, building material is needed to form new ones. Food is the source of energy and building material. It enters the digestive tract, splits (digested) into individual molecules, which are absorbed in the intestines into the blood and carried throughout the body, to every 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 mouth, proteins begin to be digested in the stomach. Yet most of the breakdown reactions of carbohydrates, proteins and all lipid breakdown reactions occur in the small intestine under the influence of pancreatic and intestinal enzymes.
Undigested parts of food are excreted from the body.
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 protein digestion
Proteins or polypeptides of food begin to break down in the stomach under the action of the enzyme trypsin to oligopeptides that enter the small intestine. Here, pancreatic juice enzymes act on oligopeptides - elastase, chymotrypsin, trypsin, carboxypeptidases A and B. The result of their joint work is the breakdown of oligopeptides to di- and tripeptides.
Completion of digestion is carried out by intestinal cell enzymes, under the action of which short chains of di- and tripeptides are cleaved into individual amino acids, which are small enough to penetrate the mucous membrane and intestines and then enter the bloodstream.
Role of the pancreas in carbohydrate digestion
Carbohydrates-polysaccharides begin to be digested in the oral cavity under the action of the enzyme α-amylase of saliva with the formation of large fragments - dextrins. In the small intestine, dextrins under the influence of the pancreatic enzyme - pancreatic α-amylasebreak down into disaccharides - m altose and isom altose. 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.
Role of the pancreas and liver in fat digestion
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 peculiarity: 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 has frozen? We use detergents. They wash the fat, as they contain surfactants that break the layer of fat into small drops that are easily washed off with water. The function of surfactants in the intestines is performed by bile produced by liver cells.
Bile emulsifies fats - breaks down large droplets of fat into separate molecules that can be exposed to the action of the pancreatic enzyme - pancreatic lipase. Thus, the functions of the liver and pancreas during lipid digestion are performed sequentially: preparation (emulsification) - splitting.
When triacylglycerols break down, monoacylglycerols and free fatty acids are formed. They form mixed micelles, which also include cholesterol, fat-solublevitamins, bile acids. Micelles are absorbed into the intestinal cells and then enter the bloodstream.
Hormonal function of the pancreas
Several hormones are produced in the pancreas - 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, since the reactions of its transformation lead to the production of energy, without which the life of the cell is impossible.
What is the pancreas responsible for? Glucose from the blood enters the cells with the participation of several types of special carrier proteins. One of these species transports glucose from the blood into 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 that lead to a decrease in blood glucose levels:
- turning glucose into a storage carbohydrate - glycogen;
- glucose transformations that go with the release of energy - glycolysis reactions;
- transformation of glucose into fatty acids and fats - reserve energy substances.
With insufficient amount of insulin, diabetes mellitus occurs, accompanied by metabolic disorders of carbohydrates, fats and proteins.
What hormonesecretes the pancreas during fasting? 6 hours after eating, digestion and absorption of all nutrients ends. Blood glucose levels begin to drop. It is time to use spare substances - glycogen and fats. Their mobilization is caused by the pancreatic hormone - glucagon. Its production begins with a drop in blood glucose levels, its task is to increase this level. Glucagon stimulates reactions:
- conversion of glycogen to glucose;
- transformation of amino acids, lactic acid and glycerol into glucose;
- fat breakdown.
Insulin and glucagon work together to keep blood glucose at a constant level.
What is pancreatitis and how is it treated?
In diseases of the liver and pancreas, the digestion of food components is disturbed. The most common pathology of the pancreas is pancreatitis. The disease develops in case of obstruction of the pancreatic duct. Enzymes produced in the gland and capable of digesting proteins, fats and carbohydrates do not enter the intestines. This results in:
- enzymes begin to digest the organ itself, this is accompanied by severe pain in the abdomen;
- food is not digested, this leads to upset stool and severe weight loss.
Pancreatitis is treated with drugs that suppress the production of enzymes by the gland. Proper nutrition in pancreatitis of the pancreas is crucial. At the beginning of treatment for several days, it is necessary to prescribecomplete starvation. The main rule of nutrition for pancreatic pancreatitis is to choose foods and food intake that do not stimulate the production of enzymes by the gland. To do this, prescribe a fractional intake of warm food in small portions. Dishes are chosen first carbohydrate, in a semi-liquid form. Then, as the pain eases, the diet is expanded, excluding fatty foods. It is known that the pancreas, if all recommendations are followed, is fully 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 exceptional importance in digestion, as they provide the digestion of proteins, fats and carbohydrates of food.
