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Liver: Functions and Information
We all have livers, but how often do we really think about them? Unlike your heart, your liver doesn't pound when you feel nervous. Unlike your stomach, your liver doesn't make growling noises when you get hungry. As long as your liver stays healthy, it's easy not to notice. Although your liver works "behind the scenes", it's also one of the largest and most important organs in your body. It performs more than 300 functions, and helps some of your other organs do their jobs.
Where is my liver, and what does it look like?
Your liver is located in the upper right-hand part of your abdominal cavity, protected by your ribs. It is situated beneath your diaphragm and on top of your stomach, right kidney, and intestines.
By the time you are an adult, your liver weighs about three pounds. A healthy liver is dark reddish-brown in color, and is shaped like a wedge. Some doctors have described the liver's shape as that of a football that's been flattened on one side. Your liver is made up of two main lobes, or sections.
What are some of the other parts that make up my liver?
Those two main lobes are just the beginning. Each lobe is made up of thousands of hexagonally-shaped lobules. These lobules are very small; under a microscope, they look like this:
As you can see, each lobule is itself made up of numerous liver cells, called hepatocytes. Inside each lobule, the liver cells line up in radiating rows. Between each row are sinusoids. These small blood vessels diffuse oxygen and nutrients through their capillary walls into the liver cells.
The lobules are connected to small bile ducts that connect with larger ducts to ultimately form the hepatic duct. The hepatic duct transports bile produced by the liver cells to the gallbladder and duodenum (the first part of the small intestine). The gallbladder, a separate organ that works closely with the liver, is attached to the bile duct. Although it is a small organ, the gallbladder is distensible, which means it is able to stretch out (or distend) if necessary. The gallbladder stores bile and releases it back into the duct on cues from the stomach.
Did you know that at any given moment, the liver holds about 13 percent of the body's blood supply? Your liver gets blood from two distinct sources: the hepatic artery and the portal vein. Oxygen-rich blood flows in through the hepatic artery, while nutrients from the intestines come through the portal vein. Remember the sinusoids? This is where they get all that oxygen- and nutrient-rich blood.
Blood leaves your liver via a central vein in each lobule, then through a hepatic vein, one of several short veins originating within the lobes of the liver as small branches. These unite in a network of hepatic veins that lead directly to the inferior vena cava. This major vein collects blood from parts of the body below your diaphragm, and passes that blood on for your heart to use.
What are the liver's functions?
As you've seen, all of the blood leaving the stomach and intestines passes through the liver. Your liver is a very important "weigh station" in the blood's journey throughout your body. But why exactly does your liver need the oxygen and nutrients supplied by your blood? What does it do?
Some people think of the liver as the body's chemical plant and inspection station. Your liver processes blood, breaking down the nutrients and chemicals your blood carries. It changes these into forms that are easier for the rest of your body to use, and also regulates the levels of most chemical in your blood.
The inspection part comes in handy because helpful nutrients are not the only things your blood carries. There are also some waste products, which your liver filters out. If you've ever seen the movie Charlie and the Chocolate Factory, think of the scale for those golden eggs. Thanks to the "Egg-dicator", the good eggs could be separated from the bad ones. This is similar to the way your liver works. It can tell the difference between nutrients and wastes. Nutrients go back into your bloodstream, and wastes are excreted as a product called bile.
Even though bile is made out of waste products, it certainly doesn't go to waste. Bile is very useful in helping to break down fats and preparing them for further digestion and absorption. Once bile is released into your small intestine, it works its magic on the food you've eaten. (Bile by-products ultimately leave your body in your feces. Blood by-products are filtered out by the kidneys and leave your body in the form of urine.) In fact, there is an entire system in your body (of which your liver is a part) that is responsible for creating, transporting, storing, and releasing bile. This is called the biliary system. The biliary system is made up of the ducts arising in the liver, the gallbladder and its duct, and the common bile duct.
All of this, however, is only the basic version of your liver's job description. Remember, your liver actually performs more than 300 separate functions – and perhaps even more that scientists don't yet fully understand. Some of its other well-known liver functions include:
- 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 (This 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 one of the end products of protein metabolism that 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 blood stream
Learn more about Tests for Liver Transplant.
November 17, 2010
November 17, 2010