I. Getting to know liver
Liver is an important organ in human body. Everyone can not survive without a healthy liver. Somebody just knows the relationship among liver, digestion and detoxification, actually liver occupies an important place in body’s operation function. Many chronic diseases such as gout, hypertension, fatty liver, allergy, obesity, neurosis and so on are directly or indirectly caused by abnormal liver function.
Most people have no enough knowledge of their body and pay less care of their health. They don’t know how to take care of themselves when they suffer diseases. Persons cannot point the exact location of liver. The rising trend of prevalence and fatality rate in liver diseases is significant, so people are afraid of hepatocirrhosis and liver cancer. There are no miracle drugs for liver diseases, but some suitable and immediate adjustments can give liver a resurgent chance. This article will introduce some information on liver structure, function, abnormal function and different kinds of hepatitis and also various treatments for liver diseases.

II. Liver structure and function
1. Where is the liver located?
The liver is the largest glandular organ of the body with complicated functions. It is situated in the upper and right parts of the abdominal cavity beneath the diaphragm, occupying almost the whole of the right hypochondrium, the greater part of the epigastrium, and not uncommonly extending into the left hypochondrium as far as the mammillary line. Healthy liver can not be touched from the surface of abdomen wall unless a skilled doctor can do it.

2. Liver structure 　
Cell is the minimum structure unit and the collection of many cells with same figures and functions can be called tissue such as nerve tissue or muscle tissue. Organs are made of tissues with same function or objective like liver, heart, stomach, kidney etc. While the collection of organs with same function and objective is organic system. For example, digestive system is made up of esophagus, stomach, small intestine and large intestine.
The liver, the largest gland in the body has both external and internal secretions, which are formed in the hepatic cells. Blood is carried to the liver via two large vessels called the hepatic artery and the portal vein. The hepatic artery carries oxygen-rich blood from the aorta (a major vessel in the heart). The portal vein carries blood containing digested food from the small intestine. These blood vessels subdivide in the liver repeatedly, terminating in very small capillaries. Each capillary leads to a lobule. Liver tissue is composed of thousands of lobules, and each lobule is made up of hepatic cells, the basic metabolic cells of the liver.
In the male the liver weighs from 1.4 to 1.6 kilogm, in the female from 1.2 to 1.4 kilogm. It is relatively much larger in the fetus than in the adult, constituting, in the former, about one-eighteenth, and in the latter about one thirty-sixth of the entire body weight. Its greatest transverse measurement is from 20 to 22.5 cm. Vertically, near its lateral or right surface, it measures about 15 to 17.5 cm., while its greatest antero-posterior diameter is on a level with the upper end of the right kidney, and is from 10 to 12.5 cm. Opposite the vertebral column its measurement from before backward is reduced to about 7.5 cm. Its consistence is that of a soft solid; it is friable, easily lacerated and highly vascular; its color is a dark reddish brown, and its specific gravity is 1.05.

3. Liver function
a. System function assignment
The liver with esophagus, stomach, small intestine and large intestine make up of the digestive system. These organs help the body to break down and absorb food. Inside these hollow organs is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. The digestive tract also contains a layer of smooth muscle that helps break down food and move it along the tract. Nutrition can be absorbed in intestine and water is absorbed in large intestine while the rest things get excreted out of body as dejecta.
During the foods digestion, pancreas produces a juice that contains a wide array of enzymes to break down the carbohydrate, fat, and protein in food. Other enzymes that are active in the process come from glands in the wall of the intestine.
Histological structure of liver is made up of four parts with different functions, it is called as tissue in physiology. The two systems are special departments and also main structure tissues in liver. One is liver system, the other is biliary system. We can call the combination of the two systems as hepatobiliary system. The other two systems are blood circulation system and reticuloendothelium system.

b. Blood circulation in liver - portal vein
Blood circulation in liver is quite different from that in the other organs. It is a double circulatory system. One is the same with the circulation in the other organs - hepatic arterial and venous system in major cycle. And the second one can be called portal vein blood circulation system. The blood in portal vein is concerned with the metabolism of both nutritional components and useless materials absorbed from the wall of digestive tract. Liver can deal with those harmful things when portal vein takes them to it. Nutritional component can be used as nutriment for human body while the other things will be destroyed and discharged.

c. Epidemic prevention function in liver
Liver reticuloendothelium system is an immunity system and is dominated by Kupffer cells. This system captures toxins and disposes them in order to protect human body from attacking and invading. And this protecting function may be gradually decreased with liver damaged degree. Immunity system produces antibody to deal with the bad things (antigen), this antibody is immunoglobulin. As a result, the rising of immunoglobulin in blood serum can be considered as a proof of liver diseases examination.

d. Metabolism function of liver
When you eat foods—such as bread, meat, and vegetables—they are not in a form that the body can use as nourishment. Food and drink must be changed into smaller molecules of nutrients before they can be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into their smallest parts so the body can use them to build and nourish cells and to provide energy. Digestion involves mixing food with digestive juices, moving it through the digestive tract, and breaking down large molecules of food into smaller molecules. Digestion begins in the mouth, when you chew and swallow, and is completed in the small intestine.
Liver is the largest glandular organ and concerned with various physiological functions. We know that carbohydrates, protein and fat are the main nutritional components in human body. Liver controls the metabolism of these three nutriments. The jobs of liver conclude bile exudation, carbohydrates store, ketone body formation, sugar metabolism fat metabolism and so on. Internal secretion system has an intimate relationship with liver, such as deoxidization and combination of adrenal gland and gonadal steroids incretion. Liver cells are also closely related to antibodies like formation of plasma protein and combination of albumin. The liver removes toxins and amino acids that don't need to be in body. The excess amino acids are broken down so that they form the urea which is excreted in the urine. Liver cells use nutritional components that absorbed via digestive system to create useful elements for body.

e. Nutriments metabolism in liver
â…°Sugars
Liver have the ability of adjusting glucose, so healthy liver can balance glucose in a suitable concentration. Insulin secretion of diabetic patients is abnormal, so these patients should pay more attention to protect a well-balanced liver function.

â…± Fats.
Fat molecules are a rich source of energy for the body. The first step in digestion of a fat such as butter is to dissolve it into the watery content of the intestine. The bile acids produced by the liver dissolve fat into tiny droplets and allow pancreatic and intestinal enzymes to break the large fat molecules into smaller ones. Some of these small molecules are fatty acids and cholesterol. The bile acids combine with the fatty acids and cholesterol and help these molecules move into the cells of the mucosa. In these cells the small molecules are formed back into large ones, most of which pass into vessels called lymphatics near the intestine. These small vessels carry the reformed fat to the veins of the chest, and the blood carries the fat to storage depots in different parts of the body.

â…² Protein.
Foods such as meat, eggs, and beans consist of giant molecules of protein that must be digested by enzymes before they can be used to build and repair body tissues. When person eat fishes and meats, the liver will decompose more free amino acid and produce ammonia to change into urea and promote the protein synthesis too.

III. Biliary tract system
1. Bile secretion
Bile in biliary tract system is excreted by liver cell and then enters into duodenum via bile duct. Bile is stored between meals in the gallbladder before the entrance. At mealtime, it is squeezed out of the gallbladder, through the bile ducts, and into the intestine to mix with the fat in food. Bile contains of bilirubin, bile acids and various electrolytes. The bile acids dissolve fat into the watery contents of the intestine, much like detergents that dissolve grease from a frying pan. After fat is dissolved, it is digested by enzymes from the pancreas and the lining of the intestine.

2. Biochemical substance in biliary tract system
a. bilirubin
Bilirubin is a product that results from the breakdown of hemoglobin. And it is harmful for human body. Bilirubin metabolism begins with the breakdown of red blood cells. Red blood cells contain hemoglobin, which is broken down to heme and globin. Heme is converted to bilirubin, which is then carried by albumin in the blood to the liver.
In the liver, most of the bilirubin is chemically attached to another molecule before it is released in the bile. This "conjugated" (attached) bilirubin is called direct bilirubin; unconjugated bilirubin is called indirect bilirubin. Total serum bilirubin equals direct bilirubin plus indirect bilirubin. Conjugated bilirubin is released into the bile by the liver and stored in the gallbladder, or transferred directly to the small intestines. Bilirubin is further broken down by bacteria in the intestines, and those breakdown products contribute to the color of the feces. A small percentage of these breakdown compounds are taken in again by the body, and eventually appear in the urine. Total and direct bilirubin are usually measured to screen for or to monitor liver or gallbladder problems.

b. bile acid
Bile acids are steroid acids found predominantly in the bile of mammals. They are produced in the liver by the oxidation of cholesterol, and are stored in gallbladder and secreted into the intestine in the form of salts. Bile acids are quite different from bilirubin and it plays an important role in nutrient absorption. When they enter into intestines, they can help the fat absorption and finally most bile acid can be absorbed again in intestines and return to liver cells. The circulation like this can be called enterohepatic circulation.

â…£ Abnormal biochemical phenomena in liver
1. Rising of ALT (GPT)
Alanine aminotransferase (ALT) is an enzyme that normally present in liver, muscle, kidney and heart cells and is also called glutamic pyruvic transaminase (GPT). ALT is released into blood when the liver or heart is damaged. The blood ALT levels are thus elevated with liver damage (for example, from viral hepatitis) or with an insult to the heart (for example, from a heart attack). So ALT can be measured to see if the liver is damaged or diseased.

a. Diseases may be caused by ALT (GPT) value：
â…°. Liver diseases
ALT is measured to see if the liver is damaged or diseased. Low levels of ALT are normally found in the blood. However, when the liver is damaged or diseased, it releases ALT into the bloodstream, which makes ALT levels go up. Most increases in ALT levels are caused by infectivity hepatitis, toxicosis hepatitis, liver cirrhosis, bile duct occlusion, jaundice and fatty liver etc. Some medications can also raise ALT levels.

â…±. Muscle diseases
ALT is increasing with the serious muscle damage, but this increase should be distinguished from that caused by supervention liver injuries. Because heart failure may make liver got a supervention injury and lead to higher ALT value.

â…². Diseases may be caused by high ALT (GPT) value:
a) Liver putrescence; liver damage; liver congestion;
b) Toxicant in body;
c) Parasitic infection and brucellosis;
d) Muscle injury.

b. Reasons of low ALT (GPT)
â…°. Effects of drug (such as oxodipine)
â…±. Lack of vitamin B6
â…². End-stage liver diseases

2. AST, GOT
Aspartate aminotransferase (AST) is an enzyme that normally present in liver, skeletal muscle, myocardium, kidney, brain, lung, pancreas and red blood cell etc. and is also called glutamic-oxaloacetic transaminase (GOT). AST is measured to see if the liver and heart are damaged or diseased.

Diseases may be caused by AST (GOT) value：
The blood AST levels are elevated with acute liver diseases while decreased with chronic liver hepatitis. The diseases conclude:
a) infectivity hepatitis; b) toxicosis hepatitis; c) hepatocirrhosis; d) bile duct occlusion and jaundice; e) fatty liver; f) heart diseases.

a. Diseases may be caused by high AST (GOT) value:
Liver cells diseases such as viral hepatitis, toxicosis hepatitis, liver necrosis, bile duct obstruction, liver neoplasms. And other diseases like injury and putrescence of skeletal muscle, muscular degeneration, brain injury, myocardium and myocardial necrosis etc.

b. Reasons of low AST (GOT):
â…°. Effects of drug (such as oxodipine)
â…±. Lack of vitamin B6
â…². End-stage liver diseases.