Clinical Section.

The human liver is an organ that is rarely seen by its possessors and with luck and good management it can function in the majority of individuals reasonably well from birth to death.

It is a large internal organ in weighing about more than one an a half kilograms  in a healthy  adult human. It is located just under the diaphragm and is partially protected by the rib cage. It is relatively fragile and surgeons wielding a scalpel near the liver have to be careful not accidentally to ‘nick’ the organ otherwise it can bleed in a manner often not easy to control.

A great deal is known about the functions of the liver which include removal from the blood passing through the organ of a wide variety of potentially harmful entities of which bacteria and alcohol are important examples. In addition the liver has an essential role as a gland secreting a number of factors important to the body. Bile is perhaps the best known substance of this kind. Bile is shed from the liver into the alimentary canal where it helps digestion and absorption of fats and vitamins A,D, E and K. Albumin is a protein secreted by the liver into the body that helps to retain blood volume.  Thrombopoietin is a protein produced in a shed from the liver that is concerned largely with the regulation of platelets that are an essential part of the blood clotting mechanism.

In addition the liver has an important role in the synthesis and breakdown of fats and carbohydrates the control of which is vital for the human body to function normally.

The liver can function abnormally in a number of ways as a consequence of many different kinds of insult (see one of the many web sites devoted to liver disease. For example, http://health.yahoo.com/ency/adam/000205/0). The best known insult to the liver is perhaps alcohol which in high quantities and over long periods of time damages the organ in such a way that it is unable to repair itself. Although this is the best known way in which the liver can be damaged in the Western World in fact there are several virus infections which can result in chronic (ie  long term) liver damage. From a global perspective these viral diseases of the liver are the main cause of cirrhosis.

One main characteristic of the liver is its capacity to regenerate when damaged. For example, the liver consists of two main lobes. If one of these is surgically removed the remaining lobe usually grows quickly to restore the amount of liver tissue that was there before the resection.  The liver tissue thus restored has the same architecture as does normal liver and functions in the same way. This regenerative capacity to restore the normal organ mass is unusual in the human body though it is shared by the kidneys; if one kidney is removed surgically the remaining kidney grows to compensate. Neither the testes nor the eyes, for example, have this regenerative capacity.

Clearly it is not common for a liver lobe to be removed but it is much more common that the liver is damaged throughout its structure by toxins that have entered and are sequestrated as a consequence of exercise of liver function.  The liver handles toxins and is structured both for this act of filtration and the subsequent detoxification but sometimes the toxins are not so easy to destroy and/or there are too many of them. In these circumstances each element of damage may be slight but nevertheless repair is necessary and will usually occur quickly by proliferation of cells local to the damage. Such  a process of decay and repair it going on continually in the liver as it does to differing degrees in other parts of the body. The skin for example is continually losing cells as a consequence of surface friction and abrasions and the process of replacement is usually so smooth that nothing seems to be changing. The lining of the alimentary canal is similarly being eroded and repaired throughout life.  

The process of damage and repair will under normal circumstances be uneventful but in certain extreme circumstances it goes wrong and the consequences in the liver are either cirrhosis, and/or liver cancer (see also http://health.yahoo.com/ency/adam/000255/0). Dealing with these two clinical conditions and their consequences constitutes a major part of Professor  Habib’s clinical practice.

It also has to be stressed in relation to Professor Habib’s clinical practice that all too often metastatic spread of cancers to the liver from tumors arising in other parts of the body occurs. Thus liver specialists often have to deal with cancers in the liver but not arising from it.