Viral Hepatitis and HIV

About the Liver and Hepatitis

The Liver and Its Many Functions

The liver is the largest organ in the human body. Approximately the size of a football, it is located in the upper right part of the abdomen.

We can't live without a functioning liver. It's the body's filter and warehouse. Almost all cells and tissues in the body depend on the liver. When something goes wrong with the liver, it can have a serious effect on almost every other organ in the body.

A little over 1-1/2 quarts of blood pump through the liver every minute, allowing the liver to quickly and effectively remove toxins and waste products from the bloodstream. At the same time, the liver stores important nutrients such as vitamins, minerals, and iron. The liver also plays a role in managing levels of certain substances in the body, such as cholesterol, hormones, and sugars, which are all necessary for survival and are potentially harmful when out of balance. The liver also has a key role in digesting food through the production of bile and controls blood-clotting factors, which prevent excessive bleeding.

What Is Hepatitis?

Hepatitis is a general term that means inflammation of the liver. "Hepa" refers to the liver and "itis" means inflammation (as in arthritis, dermatitis, and pancreatitis).

Inflammation of the liver -- hepatitis -- has several possible causes, including:

• Toxins and chemicals such as excessive amounts of alcohol;

• Autoimmune diseases that cause the immune system to attack healthy tissues in the body; and

• Microorganisms, including viruses.

HAV, HBV, and HCV infect liver cells -- called hepatocytes -- that provide the best conditions for these viruses to reproduce. In response to the infection, the body's immune system targets the liver, causing inflammation (hepatitis). If the hepatitis is severe (which can happen with HAV and HBV) or goes on for a long period of time (which can happen with HBV and HCV), hardened fibers can develop in the liver, a condition called fibrosis.

Over time, more and more normal liver tissue can be replaced by hardened scar tissue, which can obstruct the normal flow of blood through the liver and seriously affect its structure and ability to function properly. This is called cirrhosis. If the liver is severely damaged, blood can back up into the spleen and the intestines, which can result in high pressure in these organs. Consequences of this condition -- called portal hypertension -- include bleeding (variceal bleeding) and fluid in the abdomen (ascites). Significant liver damage can also reduce the production of bile needed for proper digestion and decrease the liver's ability to store and process nutrients needed for survival. Other effects of a damaged liver include the inability to remove toxins from the bloodstream, which can eventually lead to mental confusion and even coma (encephalopathy).

There are five viruses known to affect the liver and cause hepatitis: HAV, HBV, HCV, the delta hepatitis virus (HDV, which only causes problems for people infected with HBV), and hepatitis E virus (HEV). There is no hepatitis F virus. The hepatitis G virus (HGV) was originally thought to cause liver damage, but has since been found to be an apparently harmless virus and has been renamed GB virus-C (GBV-C).