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Your amazing bodyThe LiverThe liver, smooth, cone-shaped, red-brown and rubbery, is situated in the upper right part of the abdomen where it is partly protected by the rib cage. It is your largest and heaviest internal organ, weighing around 3.5 lb.(1.6 kilos). It contains 300 billion cells. It is the centre of your metabolism, a complex chemical factory and filter that controls the body's absorption of food. It carries out more than 500 separate processes concerned with regulating all the main chemicals in blood and many other life-supporting functions. Despite its complexity, the liver is remarkably resilient. It can keep going even if it loses as many as 80 percent or even 90 percent of its cells through disease or surgery. No machine could do its work. A diseased liver threatens all-round health; without a liver, life would be impossible. So, as the poet Hood wrote: "Is life worth living? - it depends on the liver".
How the liver is constructedThe liver is divided into a large right lobe, subdivided into three sections, and a smaller left lobe that tapers towards a tip, which is in contact with the stomach, intestines and oesophagus. Each lobe contains 50-100,000 small segments known as lobules. Each of these, in turn, contains hundreds of cells arranged like fine spokes radiating out from the central vein in a network of blood channels called sinusoids. These act like the holes in a sponge, carrying oxygenated and nutrient-rich blood to the liver cells.
Unlike any other organ, the liver has a double blood supply. Oxygenated blood from the heart to the liver, which needs about a quarter of the heart's total output - 1.75 pints (1 litre) a minute - comes via the hepatic artery. This subdivides into many branches within the liver to provide oxygen to all its cells. The portal vein also feeds the liver with blood. It carries nutrients from digested food such as fats and glucose from the intestines and spleen, which the liver either uses or stores, depending on the body's needs. All the liver's blood, carrying carbon dioxide and other products, drains into the hepatic veins. Bile, which assists digestion by processing fats in the small intestine and neutralising stomach acid, leaves the liver through a network of tiny bile ducts. These fuse to form the right and left hepatic ducts, which themselves fuse and carry bile to the gallbladder.  What the liver doesRaw materials for the human body, as with a household or a factory, both provide energy and repair or enhance the fabric. Also, some items need to be stored for future use or discarded as waste. The liver is central to all the many processes involved. After a meal, in a turmoil of activity, this chemical factory of the body acts a manufacturer and supplier, a depot and a waste disposal unit, a cleanser and protector, a regulator and facilitator.
What can go wrong with the liverBy far the most common cause of liver disease is too much alcohol. Drink-related disorders, notably acute hepatitis (liver inflammation), which can become chronic, and cirrhosis (liver cell death and scarring) greatly outnumber the incidence of all other liver diseases added together. The other main causes of hepatitis are viruses in contaminated food or drink when hygiene is poor, or infection in the serum from unsterilised syringes or blood transfusion. When you contract viral hepatitis, the initial symptoms are flu-like leading to jaundice, a yellowing of the skin and eyes due to build-up of bile in the blood. While symptoms can be managed, there is no cure. Drug overuse and some chemicals and poisons can also trigger hepatitis. Liver failure is a complication of hepatitis or cirrhosis when the liver functions can either not function at all or works so poorly that it affects other organs, particularly the brain. There are many other liver diseases, many in tropical countries being caused by worms and other parasites. Defects of liver structure at birth chiefly affect the bile ducts, blocking the flow and causing jaundice. In biliary atresia, the bile ducts are actually absent, also causing jaundice. Cancer can also affect the liver, usually after malignancy spreads from the stomach, pancreas or large intestine. Primary liver cancer, originating in the liver itself, is less common. The chief symptoms of liver disease besides jaundice include dark urine, vomiting of blood, easy bruising and tendency to bleed, grey or clay-coloured stools and abnormal build-up of fluid in the abdomen. Blood tests may detect early liver disease. Liver function tests show a distinct pattern of abnormalities. Biopsy (removal of a small sample of tissue for microscopic analysis) can identify the precise type of damage. Liver transplants have become increasingly successful in appropriate cases. A developing technique is to split one liver between two recipients - both livers regenerate fully within a month. Liver transplants have proved particularly valuable for children born with liver defects. Otherwise, liver transplants are reserved for patients with serious (end-stage) liver disease due to irreversible chronic liver disease, fulminant (sudden or intense) liver failure, metabolic disease or cancer. How to maintain a healthy the liverThe liver largely looks after itself and suffers little wear and tear. Drinking in moderation is the main preventive measure for liver disease. Complete abstinence from alcohol is the only way of improving the function of a drink-damaged liver. August 2001 Back to the 'Your amazing body' index. |
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