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[O] Pure Biology Smart Guides

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  1. I. PRINCIPLES OF BIOLOGY

    2. Cells
    2 Topics
  2. 3. Movement of Substances
    1 Topic
  3. 4. Nutrients
    4 Topics
  4. 5. Enzymes
    2 Topics
  5. II. MAINTENANCE AND REGULATION OF LIFE PROCESSES
    6. Nutrition in Humans
    4 Topics
  6. 7. Nutrition in Plants
    2 Topics
  7. 8. Transport in Humans
    5 Topics
  8. 9. Transport in Plants
    4 Topics
  9. 10. Respiration in Humans
    5 Topics
  10. 11. Excretion in Humans
    4 Topics
  11. 12. Homeostasis
    3 Topics
  12. 13. Nervous System
    2 Topics
  13. 14. Human Eye
    2 Topics
  14. 15. Hormones
    2 Topics
  15. III. CONTINUITY OF LIFE
    16. Cell Division
    3 Topics
  16. 17. Reproduction in Plants
    3 Topics
  17. 18. Reproduction in Humans
    5 Topics
  18. 19. Heredity
    6 Topics
  19. 20. Molecular Genetics
    2 Topics
  20. IV. MAN AND HIS ENVIRONMENT
    21. Ecology
    5 Topics
  21. 22. Our Impact on the Ecosystem
    2 Topics
Chapter 5, Topic 4
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Functions of the Liver

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Functions of the liver

  • The liver produces bile, from the breakdown of haemoglobin, which emulsifies fats.
  • The amino group of excess amino acids are removed and converted to urea (deamination) in the liver. The carbon residues of amino acids from deamination are converted to glucose in the liver. Any excess glucose is converted to glycogen.
  • Detoxification is the process of converting harmful substances into harmless products. Alcohol is broken down in the liver into harmless products like water and carbon dioxide. Hydrogen peroxide is catalyzed by catalase into harmless products like water and oxygen. Enzyme alcohol dehydrogenase converts alcohol into acetaldehyde. Acetaldehyde is used as a source of energy in cells.
  • The liver uses amino acids to synthesize plasma proteins such as prothrombin and fibrinogen. These amino acids are essential for the clotting of blood.
  • When red blood cells are worn out, they are destroyedin the spleen. Their haemoglobin is brought to the liver. The liver breaks down the haemoglobin and stores the iron released in the process.
  • When blood glucose level rises above normal, the islets of Langer hanssecreteinsulin which stimulates the liverto convert excess glucose intoglycogen. Hence, blood glucose level decreases back to normal. When blood glucose level falls below normal, islets of Langer hanssecreteglucagon which stimulates the liver to convert stored glycogen into glucose. Hence, blood glucose level increases back to normal.

Effects of excessive consumption of alcohol

  • Alcohol stimulates acid secretion in the stomach and excess acid increases the risk of gastric ulcers [1].
  • Prolonged alcohol abuse may lead to liver cirrhosis whereby the liver cells are destroyed and replaced with fibrous tissue [1].
  • Bleeding in the liver occurs for liver cirrhosis resulting in liver failure and subsequently death [1].
  • Alcohol is a depressant and it slows down some brain functions [1].
  • Under the influence of alcohol a person has reduction in self-control [1].
  • Alcoholics/ people addicted tend to neglect work/family. [1]
  • Observable effects of intoxication are slurred speech, blurred vision and poor muscular co-ordination [1].
  • Judgement deteriorates and during driving, underestimates speed, hence driving faster with slower reactions [1].