How Your Liver Works

Medically Reviewed by Minesh Khatri, MD on May 16, 2023
Written by Elizabeth Svoboda
3 min read

Your liver is the largest internal organ in your body -- and has a bunch of important jobs to do. It filters out dangerous chemicals, helps break down the food you eat, and builds proteins that keep your body in good repair.

It's a dark red wedge about the size of a football that weighs around 3 pounds. Your liver fills the space under the right side of your rib cage and nestles on top of your stomach. It's made up of two parts called lobes -- a smaller left lobe and a bigger right lobe.

After blood leaves your digestive tract and flows into your liver, the liver gears up to process a wide variety of dangerous chemicals in your bloodstream.

The cells that process these toxins break them down into molecules that are less risky for your body. For example, liver cells turn ammonia, which is released when you digest proteins, into a harmless byproduct called urea, which passes out of your system when you pee.

Your liver also safely handles the alcohol you drink by turning it into a chemical called acetate, which other tissues in your body break down into carbon dioxide and water.

You need your liver to digest anything you eat that has fat in it. Every day, your liver cells make almost a liter of bile, a dark green liquid that flows into tubes called bile ducts.

From there, the bile passes into the duodenum, a section of your small intestine, where it breaks the fat into smaller particles. This allows your cells to better absorb the nutrients your food contains.

After a meal, your liver works with another organ called the pancreas to control your levels of blood sugar (glucose).

If your blood sugar dips too low, your liver breaks down sugars it has stored in a form called glycogen and releases them into your bloodstream. This makes more sugars available to your cells for energy.

At other times, when your blood sugar is higher, your liver filters some of the glucose from your blood and stores it as glycogen to be used later.

Your liver stores most of the iron you take in and distributes it to the rest of your body.

While your liver helps process much of what moves through your digestive system, it is also a master builder. It creates a wide variety of proteins your body needs.

These proteins include clotting factors that help you stop bleeding. The liver also makes a protein called albumin, which makes sure that fluid from your blood doesn't seep into other tissues in your body.

Your liver makes a large number of proteins in the enzyme family, all of which break down different molecules so that your body can use them better.

The liver makes molecules outside the protein family as well. It creates about half of the cholesterol in your body, which is a building block for hormones like estrogen and testosterone.

When you get an infection, your liver plays a role in fighting off germs. The organ has a large number of cells called phagocytes that detect and destroy viruses and bacteria, especially those that arrive through your digestive system.

Unlike most other organs in your body, your liver has a special ability to renew damaged parts of itself. Sounds amazing, right? Don't feel bad if your reaction is that it seems more like science "fiction" than fact. According to a WebMD survey in collaboration with UPMC, more than three-quarters of respondents say they weren't aware that a liver can regrow.

The liver's ability to regenerate makes possible a procedure called a living-donor liver transplant, where you donate part of your liver to someone who needs one. After this operation, both the donor and the recipient will eventually have a fully working liver.