What Is the Role of the Liver in the Human Body?

Liver, the name of human organs, one of the five internal organs. It is an organ in the body of vertebrates that is mainly responsible for metabolic functions. It plays a role in deoxidation, storage of glycogen, and synthesis of secreted proteins in the body. The liver also makes bile in the digestive system. In medical terms, the liver is often described by the Latin prefix hepato- or hepatic. Most liver diseases have symptoms of jaundice. This is because the liver cannot continue to excrete bilirubin, so it accumulates in the body. Traditional Chinese medicine believes that the liver and the gall are the inside and the outside of the body. "Su asked the five internal organs": "The liver also has tendons, and its glory claws." The liver is also the general's official, the main concern.

Liver, the name of human organs, one of the five internal organs. It is an organ in the body of vertebrates that is mainly responsible for metabolic functions. It plays a role in deoxidation, storage of glycogen, and synthesis of secreted proteins in the body. The liver also makes bile in the digestive system. In medical terms, the liver is often described by the Latin prefix hepato- or hepatic. Most liver diseases have symptoms of jaundice. This is because the liver cannot continue to excrete bilirubin, so it accumulates in the body. Traditional Chinese medicine believes that the liver and the gall are the inside and the outside of the body. "Su asked the five internal organs": "The liver also has tendons, and its glory claws."

Chinese name

liver

Foreign name

liver

The main function

Deoxidation, storage of glycogen

Shape

Wedge-shaped

Weight

Generally weighs about 1200 1600g

Liver location

Most of the human liver is located in the right quarter rib and upper abdomen, and a small part is located in the left quarter rib area. The upper boundary is flat to the fifth rib of the right midclavicular line. The upper part is close to the diaphragm and adjacent to the right lung and heart. The duodenum is adjacent to the right bowel of the colon; the rear is in contact with the right kidney, adrenal glands and esophagus and cardia. It is the largest gland of the human body, reddish brown, soft and brittle, wedge-shaped, rounded at the right end, and thin at the left end. The upper and lower sides, the front and back edges, and the left and right leaves, generally weigh about 1200 to 1600g, accounting for about 1/50 of the adult weight. Men are slightly heavier than women. Adult livers weigh 1.4-1.8 kg for men and 1.2 for women. -1.4 kg. Fetal and neonatal livers are relatively large, reaching 1/20 the body weight. The appearance of normal liver is reddish brown, soft and brittle. The shape of the liver is an irregular wedge shape, the right side is blunt and the left side is narrow. Generally, the left and right diameter (length) is about 25cm, the anterior and posterior diameter (width) is about 15cm, and the upper and lower diameter (thickness) is about 6cm. The upper process is round and in contact with the diaphragm. The lower process is flat and adjacent to the stomach, duodenum, gallbladder and colon. The upper boundary of the liver is consistent with the position of the diaphragm. It is about the fifth intercostal space on the right. The liver has a certain degree of movement and can move up and down with changes in position and breathing. The lower boundary of the liver generally does not exceed the costal arch. It is inaccessible under the peduncle, sometimes accessible under the xiphoid process, but generally not more than 3cm, and most children can reach under the costal margin.

Liver function

(1) From the perspective of collective metabolism, it has the following functions: Vitamin metabolism. The synthesis and storage of multivitamins such as A, B, C, D and K are closely related to the liver. When the liver is significantly damaged, secondary vitamin A deficiency may cause secondary blindness or dry skin syndrome. hormone metabolism. The liver is involved in hormone inactivation. Sexual hormone disorders can occur when liver function is chronically impaired, and there can be decreased libido, axillary hair, pubic hair scarcity or shedding, impotence, testicular atrophy, male breast development, female menstrual irregularities, liver palms and spider moles, etc. The liver participates in the metabolic process of water through the action of nerves and body fluids, counteracting the effect of antidiuretic hormone in the posterior pituitary gland to maintain normal urination. The liver also regulates acid-base balance and mineral metabolism, and is an important source of heat energy for organs.

(2) The function of bile secretion and excretion: The liver produces about one liter of bile within 24 hours and is transported to the gallbladder through the bile duct. The gallbladder functions to concentrate and discharge bile to promote the digestion and absorption of fat in the small intestine.

(3) Detoxification function: Toxic substances that are foreign or metabolized in the body must be detoxified in the liver to become non-toxic or highly soluble substances, which are excreted with bile or urine.

(4) Functions related to blood: The liver is the main hematopoietic organ in the fetus, and is replaced by the bone marrow in the adult. The hematopoietic function is stopped, but its hematopoietic function is restored in some pathological conditions. In addition, almost all clotting factors are made by the liver. In the dynamic balance of the human coagulation and anticoagulation systems, the liver plays an important regulatory role. Therefore, the severity of liver damage is often parallel to the degree of coagulopathy, and patients with liver failure often have severe bleeding.

Study on in vitro culture of hepatic embryonic hepatocytes for liver tissue engineering

In order to prepare tissue-engineered livers that can be implanted in the body and achieve the ultimate goal of liver full function and permanent replacement of livers in patients with severe liver disease, scientists have done a lot of research in the field of liver tissue engineering. Current research in liver tissue engineering is mainly focused on seed cells, extracellular matrix materials (ie, three-dimensional scaffold materials), and the construction of liver tissue structure and growth and development microenvironment. Regarding the study of the construction of liver tissue, Auth et al. Cultured human bile duct epithelial cells on extracellular matrix materials to form bile duct-like structures; Kim et al. Used co-culture of endothelial cells and hepatocytes to better maintain hepatocytes Function: Sakai et al. Used a method of pre-culturing fibroblasts as a feeder layer to rapidly prepare liver cell sheet tissue with limited proliferation potential that can be used for highly specific cell transplantation. And our HE staining results show that under the conditions of the three-dimensional scaffold culture in this experiment, 15d mouse embryonic hepatocytes can be guided to form vascular-like structures and liver tissue-like structures, which is different from the results of planar culture in vitro culture flasks. Colony-like growth was common in cell culture, and no vascular-like structure was formed. In the field of liver tissue engineering, the choice of seed cell source is very important. In the hyaluronic acid scaffold material prepared by Zavana, under the action of the extracellular matrix secreted by fibroblasts, in vitro cultured mature hepatocytes can see the reconstruction of cell-cell contact, and the function of hepatocytes to secrete ALB is maintained for 14 days. The results of our immunohistochemical ALB expression suggest that embryonic liver cells have the function of secreting ALB under the conditions of three-dimensional scaffold culture. With the in vitro culture time, until the 28th day, the level of ALB expression of these cells increased. Positive PAS results also indicated the presence of hepatic glycogen in the cytoplasm on the 28th day of in vitro culture. ALB is a specific marker of liver cells and an important indicator of liver function expression; the synthesis and storage of liver glycogen is also one of the indicators of liver function. The above indicators fully reflect the 15th day of mouse embryonic liver cells as seed cells Feasibility and superiority. Because of the higher proliferation ability and differentiation potential and lower immunogenicity of embryonic hepatocytes, it should have great clinical application value for improving liver function and repairing liver damage, and it is an ideal source of seed cells. In this experiment, AFP was positively expressed on stent sections cultured for 1 week and 4 weeks. Since AFP is expressed only in fetal liver cells and adult hepatic stem cells, it is negative in mature hepatocytes, suggesting that culture under 3D scaffold conditions Most of the cells in the liver-like tissue at 4 weeks still have the characteristics of stem cells. How to add specific cytokines to induce the differentiation of embryonic hepatocytes into mature hepatocytes or bile duct epithelial cells under the condition of three-dimensional scaffold culture. This is the embryonic liver cell as a seed of liver tissue engineering A problem for the cell. During the construction of liver tissue engineering, scaffold materials and processes are also one of the key points. In terms of three-dimensional scaffolding technology, EnvisionTechnoloty in Germany and Clemson University in the United States have developed CellPrinting and CellPlotter that can spray cells and matrix materials. Valerie in the United States successfully prepared a three-dimensional structure of the liver tissue platform, and used the hydrogel of the cell as a scaffold material to assemble the liver tissue, and received good results. We use a "three-dimensional controlled assembly system" composed of a biomaterial rapid prototyping machine and control software developed by the Laser Rapid Prototyping Center of Tsinghua University. We select the best material distribution and microstructure distribution, and use computer-aided design software to perform liver lobular structures. Model design, using rapid prototyping technology, single-nozzle composite digital spray technology for precise spray forming of 15d embryonic liver cell material composites to prepare liver-like tissue precursors with a diameter of 100 m. The results show that the matrix material composed of gelatin and fibrinogen plus thrombin cross-linking used in the experiment has biomedical characteristics such as biocompatibility, low immunogenicity, and non-toxicity. The cell three-dimensional growth scaffold prepared from it and embryonic liver cells can maintain the metabolism and growth phenotype of cells in liver-like tissue, and provide experimental data for further exploration of the best materials and processes for assembling liver tissue engineering.