Food digestion also involves a set or accessory organs which carry out the processes of digestion smoothly. In addition to the tongue, the teeth and the salivary glands, other structures which act as accessory to the digestive system are: (1) The liver, gall bladder and bile ducts 2. The pancreas.
The liver is the largest organ in the body and weight between 1 and 2.3 kg (2 to 5 pounds) Fig 63. The liver anterior view and is heavier in males than females. It is situated in the upper part of the abdominal cavity immediately below the diaphragm. It occupies mainly the right hypochondria and epigastria, but extends partly into the left hypochondria.
The liver is enclosed in a thin capsule and completely covered by a layer of peritoneum. The shape of the liver is irregular. It may be conveniently divided into right and left lobes and described as having superior, inferior, anterior and posterior surfaces.
Structure of liver:
The liver is made up of a large number of lobules consisting of columns of liver cells. Each lobule has a special blood supply and from it passes a small bile duct which carries the bile secreted by the liver cells and unites with similar ducts from other lobules until finally the larger bile ducts are formed. The liver has a double set of blood vessels- the hepatic artery and the portal veins bringing blood into the liver cells which enter at the portal fissure and a single set removing blood from it to the inferior vena cava.
The liver being an extremely active organ performs several important functions of the processes of the body. They are summarized briefly as:
1. Secretes bile.
2. Stores glycogen, Vitamin B, 2 and iron.
3. Synthesis's Vitamin A.
4. Breaks down protein with formation of urea.
5. Produces Plasma Protein.
6. Desaturates fat.
7. Produces heat.
8. Breaks down protein with the formation of urea.
9. Detoxicates drugs and other noxious substances.