The functions of the liver
Monacia Williams, Contributor

Last week, we concluded our study of digestion. We learned that some of the end products of digestion, glucose and amino acids, along with minerals and the water-soluble vitamins B group and C enter the blood capillaries that are associated with the villi in the small intestine. These blood capillaries eventually join to form the hepatic portal vein, which takes the digested products to the liver. Remember also, that some of the products of digestion, namely the fatty acids and the fat-soluble vitamins A, D, and E are removed by the lacteals which connect to the lymphatic system.

The lesson ended with a promise that we would take a closer look at one of the most marvelous organs in the human body, the liver.

Do you remember what was said? That the liver functions as a chemical factory, a food store and a central heating system? Bet you did not know that? Today, we are going to investigate why these statements are true.

The liver as a chemical factory

What would you expect to take place in a chemical factory? Chemical reactions, right? That is exactly what takes place there. These reactions include:

• The breakdown of haemoglobin in old red blood cells to produce the bile pigments. Remember that this bile is stored in the gall bladder from which it is released through the bile duct to be used in digestion. The breakdown also releases iron, which is stored in the liver.
• The removal of the amino group from amino acids. This process is known as deamination. The amino group is converted to urea, which is excreted from the body in the form of urine. The remaining amino acid is converted to carbohydrate, which can be used by the body.
• The transfer of an amino group from one amino acid to another. This process is known as transamination.
• The production of fibrinogen, which is needed for the clotting of blood.
• The control of the amount of glucose in the blood. It does this with the help of two hormones which are produced in the pancreas. The hormones are insulin and glucagon.
• The making of cholesterol. This is used to make and repair cell membranes.
• The breaking down of harmful substances such as alcohol and drugs, as well as the toxins given off by bacteria. This process is known as detoxification and helps to cleanse the blood.
• The breakdown of hormones that are no longer needed by the body.
• The synthesis of Vitamin A from carotene.

The liver as a food store

• Many products are stored in the liver. These include:
• Excess glucose, which is converted to glycogen and stored.
• Vitamins A, B, D, E and K.
• Potassium, copper and iron

The liver as a central heating system

The liver has a very high metabolic rate, that is, many reactions are taking place in the liver at any given time. These reactions produce a high level of heat, which is transported around the body by the blood. This helps to maintain the body temperature.

Do you now agree with the original statement that the liver is a marvelous organ? We have already looked at the characteristics of the nutrients that we must include in our diets. Next week, we will look what constitutes a balanced diet and how the presence of imbalances

impacts on our health. See you then! Have a productive week!

These Herbert Morrison Technical High School students authentically represented Jamaica's heritage during the school's Jamaica Day Celebrations recently. - Photo by Sheena Gayle