What Is the Liver?

The liver, a very complex and hard working structure, is the largest organ in the body. The liver filters the blood and has hundreds of other functions, most of which are necessary to life and are not done elsewhere in the body. Every part of the liver is capable of performing all of its tasks, and it is the only organ in the body with this capability. The liver has an amazing ability to recover from injury and regenerate new tissue.

Where Is the Liver Located?

The liver is a multi-lobed organ located in the front of the abdominal cavity. It lies directly behind the diaphragm (the muscle that aids in breathing and separates the chest from the abdomen) and directly in front of the stomach. The liver is positioned horizontally across the front of the abdomen, with proportionally more of the liver on the right side.

What Is the General Structure of the Liver?

The normal liver is a deep red color with a firm consistency. It is divided into several different lobes, and each lobe is made up of multisided units called hepatic lobules. Each lobule is composed of a curved sheet of cells, which enclose numerous blood filled cavities known as sinusoids. These sinusoids give the liver a spongy texture and enable it to hold large amounts of blood.

Two major blood vessels enter the liver: The portal vein carries most of the blood to the liver and contains nutrients from the gastrointestinal tract, as well as chemicals and drugs that have been absorbed into the body. The hepatic artery carries oxygen-rich blood to the liver from the heart and lungs.

Two major conducting structures exit the liver. The hepatic veins drain blood from the liver. The bile ducts take bile from the liver cells to the gall bladder, a pear shaped pouch located under the liver.

What Are the Functions of the Liver?

The liver regulates the levels of many different chemicals and substances in the blood, and it excretes bile, a yellowish-green digestive fluid. All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down the nutrients, chemicals, and drugs into forms that are easier for the rest of the body to use. There are more than 500 vital functions associated with the liver. Some of these functions include the following:

The production of bile, which is released into the gastrointestinal tract to help break down fats in the small intestine during digestion. The liver makes bile continuously, even when food is not being digested, and extra bile is stored in the gallbladder.

The production of certain proteins that circulate in the blood, such as albumin and several factors responsible for clotting.

The production of cholesterol and special proteins (lipoproteins) that help carry fats through the body.

The conversion of excess glucose (sugar) into a starch-like compound called glycogen and storage of this glycogen in the liver. Glycogen can later be converted back to glucose for energy whenever it is needed.

The storage of blood that can be shunted immediately into the general circulation when needed following injury or sudden blood loss.

The regulation of blood levels of amino acids, which form the building blocks of proteins.

The storage of iron that is used in the processing of hemoglobin in the blood. Hemoglobin is essential for carrying oxygen in the blood.

The conversion of ammonia in the blood to urea. The bacteria of the intestinal tract produce ammonia as they break down proteins, and ammonia can accumulate in the blood at potentially toxic levels. Urea is a safer product than ammonia and is excreted (passed out of the body) in the urine.

Clearing the blood of foreign substances, such as medications and anesthetic agents that are administered to animals.

Resisting infections by producing immune factors and filtering bacteria from the blood stream.