11.19: The Liver
The liver is situated in the abdominal cavity adjacent to the diaphragm (see diagrams 2 and 14). It is the largest single organ of the body and has over 100 known functions. Its most important digestive functions are:
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- the production of bile to help the digestion of fats (described above) and
- the control of blood sugar levels
Glucose is absorbed into the capillaries of the villi of the intestine. The blood stream takes it directly to the liver via a blood vessel known as the hepatic portal vessel or vein (see diagram 11.15).
The liver converts this glucose into glycogen which it stores. When glucose levels are low the liver can convert the glycogen back into glucose. It releases this back into the blood to keep the level of glucose constant. The hormone insulin , produced by special cells in the pancreas , controls this process.
Diagram 11.15 - The control of blood glucose by the liver
Other functions of the liver include:
- 3. making vitamin A ,
- 4. making the proteins that are found in the blood plasma ( albumin, globulin and fibrinogen ),
- 5. storing iron ,
- 6. removing toxic substances like alcohol and poisons from the blood and converting them to safer substances,
- 7. producing heat to help maintain the temperature of the body.
Diagram 11.16 - Summary of the main functions of the different regions of the gut