Function of Liver

• What are the main functions of the mammalian liver?

  Storage of glycogen, formation of urea, and detoxification
• What is glycogenesis and when does it occur?

  • Glycogenesis is the conversion of glucose into glycogen.
  • It occurs when insulin triggers the process after an increase in blood glucose concentration.
• How does glycogenesis affect blood glucose concentration?

  It decreases blood glucose concentration by removing glucose molecules from the bloodstream
• Where is glycogen stored in the liver?

  Inside hepatocytes
• Why is glycogen considered a compact storage molecule?

  Because it allows for easy release of glucose when needed
• What happens to dietary proteins in the liver?

  • Dietary proteins are broken down into amino acids.
  • Amino acids are absorbed into the blood and transported to the liver via the hepatic portal vein.
  • Excess amino acids undergo deamination and the ornithine cycle.
• What is deamination?


  Deamination is the removal of the amino group from each amino acid
• What is produced when the amino group and an extra hydrogen atom are removed during deamination?

  Ammonia
• What can the remaining part of the amino acid after deamination be converted into?

  It can enter the Krebs cycle, be converted to glucose, or be converted to glycogen or fat for storage
• What is the ornithine cycle?

  • The ornithine cycle is the process that converts ammonia into urea.
  • Ammonia is combined with carbon dioxide to form urea.
  • One molecule of urea is produced from one molecule of carbon dioxide and two amino groups.
• Why is ammonia converted into urea in the liver?

  To avoid the toxic effects of ammonia
• How is urea transported after its formation in the liver?

  Urea diffuses through the phospholipid bilayer of hepatocytes and is transported to the kidneys dissolved in blood plasma
• What substances undergo detoxification in the liver?

  Alcohol and hydrogen peroxide
• What is detoxification in the liver?

  • Detoxification is the breakdown of substances that are not needed or are toxic.
  • It helps to remove harmful substances from the body.
• What substance is produced from the detoxification of alcohol?

  Ethanal
• What happens to ethanol after it is absorbed in the stomach?

  It is transported in the blood until it reaches the hepatocytes
• What enzyme is responsible for converting ethanol into ethanal in the liver?

  Alcohol dehydrogenase
• What is the consequence of continuous alcohol detoxification on fat metabolism in hepatocytes?

  Hepatocytes do not metabolise as much fat and instead store it
• What condition is caused by the storage of fat in hepatocytes due to continuous alcohol consumption?

  Fatty liver
• What severe problem can arise from the condition known as fatty liver?

  Cirrhosis
• What causes cirrhosis in the liver?

  Excessive alcohol consumption
• What are the steps involved in the detoxification of alcohol in the liver?

  • Ethanol is absorbed in the stomach.
  • Ethanol is transported in the blood to the hepatocytes.
  • Alcohol dehydrogenase converts ethanol into ethanal.
  • Ethanal is converted into other molecules that enter respiration.
• What are the effects of continuous alcohol consumption on liver function?

  • Reduced fat metabolism in hepatocytes.
  • Accumulation of fat leading to fatty liver.
  • Impaired liver functions due to stored fat.
  • Potential progression to cirrhosis.