THE LIVER - A VITAL ORGAN
The liver is the largest organ in the body and plays a vital role in regulating life processes. Located behind the lower ribs on the right side of the abdomen the liver weighs about 1.4kgs and is roughly the size and shape of a small football.
Functions of the Liver
This vital organ performs many complex functions. Some of these are:
1. Conversion of food into the chemicals necessary for life and growth
2. The manufacture and export of important substances used by the rest of the body
3. Processing of drugs absorbed from the digestive tract into forms that are easier for the body to use
4. The detoxification and excretion of substances that otherwise would be poisonous to the body. The liver converts these toxins into substances that can be easily eliminated from the body.
All of the blood leaving the stomach and intestines must pass through the liver before reaching the rest of the body. In essence, the liver can be thought of as the body’s refinery.
Oxygenated blood that has returned from the lungs to the left ventricle of the heart is pumped to all the tissues of the body. This is called the systemic circulation.
After reaching the tissues, blood is returned to the right side of the heart. From there it is pumped to the lungs and then returned to the left side of the heart after taking up oxygen and giving off carbon dioxide. This is called the pulmonary circulation.
Blood from the gut and the spleen flow to and pass through the liver before returning to the right side of the heart. This is called the portal circulation and the large vein through which blood is brought to the liver is called the portal vein.
The liver also receives some blood directly from the heart via the hepatic artery. In the oesophagus, stomach, small intestine and rectum, the portal circulation and veins of the systemic circulation are connected. Under normal conditions, there is little to no back flow from the portal circulation into the systemic circulation.
In patients with advanced liver disease however, there is often a rise in the blood pressure in the portal vein (this is called portal hypertension). Connections can then develop between the portal and systemic systems. If these connections occur in certain areas (eg. the lower end of the oesophagus), engorged veins can form under the increased pressure. These veins can burst and bleed causing serious consequences.
The liver is the site of bile formation. Bile contains bile salts, fatty acids, cholesterol, bilirubin and other compounds. The components of bile are synthesized and modified in the hepatocytes (the main cell type in the liver) and secreted into small bile ducts within the liver itself.
These small bile ducts form a branching network of progressively larger ducts and ultimately become the common bile duct which takes bile to the small intestine.
Bilirubin is a yellow pigment that is made up from the breaking down of old red blood cells. Bilirubin is taken up from the blood by hepatocytes, modified in the hepatocytes to a water soluble form and secreted into the bile.
The Liver helps you by:
• Producing quick energy when it is needed
• Manufacturing new body proteins
• Preventing shortages of body fuel by storing certain vitamins, minerals and sugars
• Regulating transport of fat stores
• Regulating blood clotting
• Aiding in the digestive process by producing bile
• Controlling the production and excretion of cholesterol
• Neutralizing and destroying poisonous substances
• Metabolising alcohol
• Monitoring and maintaining the correct level of many chemicals and drugs in the blood
• Cleansing the blood and discharging waste products into the bile
• Maintaining hormone balance
• Serving as the main organ of blood formation before birth
• Helping the body to resist infection by producing immune factors and by removing bacteria from the bloodstream
• Regenerating its own damaged tissue
• Storing iron
Common Liver Diseases
There are many types of liver disease but among the most important are:
* Viral hepatitis
* Alcohol related liver disease
* Fatty liver disease
* Cancer of the liver
Symptoms and signs of liver disease
Many patients with liver disease will have no symptoms (i.e.: they are asymptomatic) and it is important to note that there are numerous other causes for the following symptoms.
1. Abnormally yellow discoloration of the skin and eyes. This is called Jaundice which is often the first sign of liver disease.
2. Dark urine
3. Gray, yellow or light-coloured stools
4. Nausea, vomiting and/or loss of appetite
5. Abdominal swelling
6. Sleep disturbances, mental confusion and coma are present in severe liver disease. These result from and accumulation of toxic substances in the body which impair brain function
7. Fatigue or loss of stamina. This is usually the only symptom of liver inflammation [hepatitis]
8. Loss of sexual drive or performance.
1. Limit alcohol intake – NHMRC safe drinking guidelines recommend that women not drink more than one standard drink (10g ethanol) per day, and men not more than two drinks (20g ethanol). A standard drink contains about 10g ethanol and comprises:
• One middie (280ml) glass of standard beer (heavy).
• One stubbie or can (375ml) of mid strength beer (3.3% alcohol)
• One glass (100ml) of wine
• One nip (30ml) of spirits
However, patients with liver disease of any cause should drink alcohol very sparingly if at all. People with advanced liver disease such as cirrhosis need to abstain from alcohol altogether.
2. Be cautious about mixing drugs – in particular alcohol and many “over the counter” and prescription medicines. “Over the counter” includes vitamin preparations as some of these have been found to be liver toxic.
3. Avoid exposure to chemicals contained in pesticides and other industrial type preparations
4. Maintain a healthy well balanced diet
5. Consult your doctor if you notice any signs or symptoms of liver disease