Your liver: An owner's guide

The liver is one of your body's largest and most important organs. Located just under your rib cage on the right side of your abdomen, it's about the size of a football, weighs 3 to 4 pounds and performs more than 500 vital functions. Without it, you couldn't absorb food, remove toxic substances from your body or stay alive.

Your liver is incredibly resilient. It can remain functional after losing 80 percent to 90 percent of its cells to disease. It can completely regenerate itself in a few weeks even if much of it has been removed during surgery.

But it's not indestructible. Toxins such as alcohol and drugs, and viruses such as hepatitis B and C can cause permanent liver damage. With advanced liver disease (cirrhosis), healthy liver tissue is replaced with scar tissue and your liver is no longer able to repair itself, gradually losing function and eventually failing. Although early-stage liver disease is more treatable now than in the past, cirrhosis is usually only curable with a liver transplant.

Your liver: A brief anatomy lesson

A healthy liver is cone-shaped, with a smooth, rubbery texture. Its color is dark reddish-brown because at any given moment it holds a pint of blood. It's divided into lobes: a large right lobe and smaller left lobe that tapers toward a tip. Unlike most other organs in your body, your liver has a dual blood supply. Most of its blood comes from the portal vein, which carries nutrients and toxins from your digestive system. The rest comes from the hepatic artery, which supplies oxygen-rich blood from your heart.

Everything you eat, drink, breathe and absorb through your skin eventually reaches your liver. Its 300 billion cells control a process called metabolism, in which your liver breaks down nutrients into usable byproducts. These byproducts are delivered to the rest of your body by your bloodstream. Your liver also metabolizes toxins into byproducts that can be safely eliminated. Some of these byproducts are routed into your bloodstream and carried to your kidneys, which filter them so that they can be excreted in urine. Others are carried away by bile, a yellow or greenish fluid produced by your liver. These byproducts flow through bile ducts to your gallbladder and intestines so that they can be excreted in feces.

Liver anatomy

Liver anatomy

Your liver is located under your rib cage, which helps protect it from injury. The liver plays a vital role in digesting food and filtering toxins from your bloodstream.

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What your liver does

Although separating nutrients from waste is one of your liver's most important functions, it's not the only one. Your liver is also a storage depot for sugar (glucose), which is released when you need energy. And it's a chemical factory, producing many substances that perform vital tasks in your body. Some substances produced by the liver include:

• Albumin, a protein that regulates the exchange of water between blood and tissues
• Bile, a fluid that carries away waste and digests fat in the small intestine
• Cholesterol, a substance needed by every cell in the body
• Clotting factors, which help stop bleeding
• Globin, part of the oxygen-carrying hemoglobin in blood
• Immune factors, which protect against infection

How to protect your liver

Excessive alcohol consumption over many years is the leading cause of liver disease. Too much alcohol can make a normal liver swell with fat, causing a condition called fatty liver. If the fat becomes inflamed, it can lead to either alcoholic hepatitis, which causes serious but often reversible liver damage, or cirrhosis, which causes irreversible liver damage. Because of extensive scarring, a cirrhotic liver shrinks to a fraction of its former size.

Normal and diseased livers

Normal and diseased livers

The liver and its cells — as seen through a microscope — change dramatically when a normal liver becomes fatty or cirrhotic.

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Looking ahead

In the future, liver disease treatments may include genetic therapy, as well as new vaccines and antiviral drugs to prevent and treat hepatitis C and other hepatitis viruses that cause permanent liver damage. Researchers are also working to develop an artificial liver that performs the liver's filtering functions, just as dialysis filters blood in people with kidney failure.

For now, though, the best way to control liver disease is to keep it from starting. By being careful with alcohol, drugs and chemicals, you can ensure that your liver lasts a lifetime.