The Liver: Anatomy and Functions

Anatomy of the liver

The liver is located in the upper right-hand portion of the abdominal cavity, beneath the diaphragm, and on top of the stomach, right kidney, and intestines.

Shaped like a cone, the liver is a dark reddish-brown organ that weighs about 3 pounds.

There are two distinct sources that supply blood to the liver, including the following:

• Oxygenated blood flows in from the hepatic artery

• Nutrient-rich blood flows in from the hepatic portal vein

The liver holds about one pint (13 percent) of the body's blood supply at any given moment. The liver consists of two main lobes, both of which are made up of thousands of lobules. These lobules are connected to small ducts that connect with larger ducts to ultimately form the hepatic duct. The hepatic duct transports the bile produced by the liver cells to the gallbladder and duodenum (the first part of the small intestine).

Functions of the liver

The liver regulates most chemical levels in the blood and excretes a product called bile, which helps carry away waste products from the liver. All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down the nutrients and drugs into forms that are easier to use for the rest of the body. More than 500 vital functions have been identified with the liver. Some of the more well-known functions include the following:

• Production of bile, which helps carry away waste and break down fats in the small intestine during digestion

• Production of certain proteins for blood plasma

• Production of cholesterol and special proteins to help carry fats through the body

• Conversion of excess glucose into glycogen for storage (glycogen can later be converted back to glucose for energy)

• Regulation of blood levels of amino acids, which form the building blocks of proteins

• Processing of hemoglobin for use of its iron content (the liver stores iron)

• Conversion of poisonous ammonia to urea (urea is an end product of protein metabolism and is excreted in the urine)

• Clearing the blood of drugs and other poisonous substances

• Regulating blood clotting

• Resisting infections by producing immune factors and removing bacteria from the bloodstream

When the liver has broken down harmful substances, its by-products are excreted into the bile or blood. Bile by-products enter the intestine and ultimately leave the body in the form of feces. Blood by-products are filtered out by the kidneys, and leave the body in the form of urine.