The Liver - How it Works

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Introduction

Your liver is one of the largest organs in your body, second only to your skin.  Your liver is located in your right upper abdomen and is protected by your ribcage.  Your liver performs over 100 functions—most of them are related to keeping you alive and healthy.

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Anatomy

Your liver is divided into right and left lobes.  It is further divided into smaller lobes called the caudate and quadrate lobes.  The right lobe is the largest part of your liver.
 
About 25% of your total blood volume passes through your liver each minute.  Your liver receives blood from two sources, the portal vein and the hepatic artery.  Additionally, blood from your spleen drains into the splenic vein and connects with the portal vein.  Most of the blood received by your liver is from the portal vein.  Blood travels from your heart and through your gastrointestinal tract before returning to your liver via the portal vein.  This way, your liver is the first to receive substances from digested food. 
 
Your liver receives toxins, alcohol, nutrients, germs, and medications from your digestive tract.  As a result, one function of the liver is to metabolize toxins, alcohol, nutrients, and medications.  The liver kills germs that enter your body through your intestines.
 
The hepatic artery is the second source of blood supply to the liver.  Blood delivered through the hepatic artery comes directly from the heart.  It is higher in oxygen than blood from the portal vein. 
 
Once inside the liver, blood from the portal vein and the hepatic artery mix.  The blood flows through tiny blood vessels in the liver called sinusoids.  Components in the blood are delivered by the sinusoids to the hepatocytes.  Hepatocytes are the major cell type in the liver.  The hepatocytes metabolize nutrients, toxins, and drugs from the blood.  Blood leaves the liver through the hepatic vein.  The blood flows through the vena cava and back to the heart.  The hepatocytes perform numerous chemical processing functions that are necessary to keep you healthy and alive.  The hepatocytes play a role in blood clotting and secreting albumin.  Albumin helps to regulate the amount of fluids in your body.
 
The hepatocytes metabolize nutrients including carbohydrates, fats, cholesterol, and proteins.  Your liver functions to maintain appropriate ammonia and blood sugar (glucose) levels.  Correct levels of ammonia are necessary for good brain functioning.  Your cells use blood sugar for energy.  Your liver also stores vitamins, iron, and other minerals.
 
Another function of the hepatocytes is to filter certain compounds from the blood.  Blood arriving from the portal vein contains environmental toxins that were absorbed in the stomach.  The liver “detoxifies” or filters the toxins from the blood.  The toxins are secreted by your kidneys in urine or secreted into bile that leaves the liver.
 
Bile is a substance that is produced by your liver and stored in your gallbladder.  When you eat fatty foods, bile leaves your gallbladder via the common bile duct and travels to the duodenum, the first part of your small intestine.  There, the bile aids in breaking down fats for digestion.
 
Bile receives its yellow color from bilirubin.  Bilirubin is formed from the break down old red blood cells.  Your spleen breaks down your old red blood cells.  The hepatocytes metabolize the hemoglobin in old red blood cells into a form of bilirubin that can be excreted with bile.  This form of bilirubin is called “conjugated bilirubin.”  It eventually is removed from your body in your urine or stools.  Only a very small amount returns to your bloodstream.
 
The liver is unique in that it can regenerate itself.  If part of the liver is removed, the liver can re-grow tissue.  You need a liver to live.  If the liver is severely damaged, it needs to be replaced.
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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on February 16, 2022. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.