01 May 2013

# 57 Assimilation and role of the liver

Assimilation is the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells.

Role of liver in the metabolism of glucose and amino acids
  • Excess glucose in the blood arriving at the liver is converted into glycogen (animal starch) for storage, or broken down through respiration, producing energy for other purposes.

  • Amino acids cannot be stored in our body, so any that is excess has to be dealt with in the liver. 
    - Some amino acids are transaminated to produce a different amino acid. 
    - The rest are deaminated to produce ammonia (NH3and a keto acid       

    NH3 is converted into urea, which is transported to the kidneys and excreted. 
    + The keto acid is used primarily as energy for liver cells

    So Deamination is the removing of nitrogen-containing part of amino acids to form urea and using of the remainder of amino acid to provide energy to the liver cells.  

Role of liver in the breaking down of alcohol and other  toxins
  • Breaking down any toxins absorbed from the alimentary canal, including drugs such as alcohol. Cells in the liver are able to convert many toxins to harmless substances that can be transported in the blood and excreted from the body.

Role of fat as an energy storage substance
  • Fatty acids and glycerol pass into the lymphatic system and then the bloodstream. Once in the blood nutrients are carried to all cells of the body. Some are oxidised to produce energy and others are used to repair the cell, build new cells.
  • Fat is a good storage compound – it releases twice as much energy as carbohydrates when respired, and act as insulation in the skin. Some nerve cells form a myelin sheath from fat, to prevent electrical impulses from leaking out.


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