The functions of the liver

• what are the main functions of the liver?

  • detoxification - breakdown alcohol, toxins and drugs
  • carbohydrate and lipid metabolism
  • breakdown old erythrocytes
  • production of cholesterol
  • metabolism of proteins - deamination of excess amino acids to create urea, transamination - conversion of one amino acid to another
  • produces bile - emulsify fats
• what particularly is detoxified?

  ethanol, alcohol
• what is the process of deamination?

  amino acid + oxygen -> ammonia + keto acid
• what happens in the Ornithine Cycle?

  • ammonia is detoxified to produce urea by combining it with CO2
• what is the purpose of transamination?

  • allows you to produce new amino acids from existing amino acids in your body
• what is the role of catalase?

  breaks down hydrogen peroxide into water and oxygen
• how does methylation render toxins harmless?


  • transforms toxins into a form that is easier to package up and eliminate
• what qualities does the liver have?

  • high regeneration ability - deals with toxins
• what is ethanol?

  • C2H5OH
  • depresses the CNS
  • lipid soluble - easily diffuse across cell membrane
• how is ethanol broken down?

  • ethanol -> ethanal, using alcohol dehydrogenase and NAD
  • ethanal -> ethanoic acid, using aldehyde dehydrogenase and NAD
  • ethanal causes symptoms of hangover
• how is NAD used in the breakdown of ethanol?

  • hydrogen carrier used in respiration
  • involved in oxidation and reduction reactions, reduced NAD is used in respiration to generate lots of ATP
• what does it mean to have intense hangover symptoms?

  • defective gene for aldehyde dehydrogenase so get hangover symptoms quicker
• how does too much alcohol consumption develop a fatty liver?

  • leads to disorders of metabolic functioning of liver
  • initial stages involves accumulation of fats in liver cells
  • breakdown of ethanol produced reduced NAD, so reactions using oxidised NAD are less likely to happen causing fatty acid accumulation depositing around the liver
• what are the causes and consequences of cirrhosis?

  • liver is injured - excess alcohol consumption, infection e.g.
  • scar tissue forms (liver tries to repair itself)
  • as cirrhosis gets worse, more and more scar tissue forms making it difficult for liver to do its job
  • damage can't be undone, can be life-threatening
• describe the development of liver disease

  • deposits of fat causes liver enlargement
  • scar tissue forms
  • growth of connective tissue destroys liver cells (cirrhosis)