Liver

The liver is the body's largest internal organ and one of its busiest, performing hundreds of metabolic tasks. It is essential to digestion because it produces bile, but it also processes nutrients, neutralizes toxins, and manufactures vital proteins.

Structure and Location

The liver sits just beneath the diaphragm and fills most of the right upper quadrant of the abdomen, partly protected by the lower ribs. Anatomically it is divided into four lobes: the large right and left lobes plus the smaller caudate and quadrate lobes. Surgeons more often use the Couinaud system, which splits the liver into eight functional segments based on blood supply, so that portions can be removed independently.

The liver has an unusual dual blood supply. About 75 to 80 percent of its blood arrives through the portal vein, carrying nutrient-rich (but oxygen-poor) blood directly from the intestines, while the remaining 20 to 25 percent comes via the hepatic artery, delivering oxygenated blood. This arrangement lets the liver screen everything absorbed from the gut before it reaches the rest of the body.

Function

The liver makes bile, which is stored in the gallbladder and released to help digest and absorb fats. It also metabolizes carbohydrates, fats, and proteins; stores glucose as glycogen and releases it to keep blood sugar steady; detoxifies drugs, alcohol, and metabolic waste; and synthesizes key proteins including albumin and clotting factors. It processes old red blood cells, producing bilirubin that is excreted in bile.

Clinical Relevance

Because it handles toxins and nutrients, the liver is vulnerable to many insults. Viral hepatitis, chronic alcohol use, and fatty liver disease can cause inflammation and scarring that progresses to cirrhosis and liver failure. Blocked bile flow or red-cell breakdown causes jaundice (yellowing of skin and eyes). Liver cancer and portal hypertension are other serious conditions. This content is educational and not a substitute for medical advice.