Excretion

• What crucial role does the liver play in the body?

  Metabolism
• What do metabolic reactions generate that can harm cells?

  Waste products like CO2 and nitrogenous substances
• What is excretion?

  Removing metabolic waste from cells
• How is CO2 excreted from the body?

  By the lungs after respiration
• Which metabolic waste product is metabolised in the liver?

  Urea
• What is the liver's function in detoxification?

  • Breaks down toxic substances
  • Converts them into less harmful compounds
  • Excretes these compounds from cells
• What happens to amino acids in the liver?

  They are broken down through deamination
• What toxic substance is produced during amino acid breakdown?

  Ammonia
• What is formed when ammonia combines with CO2?

  Urea
• Where does the ornithine cycle occur in the liver?

  Partially in the mitochondria
• How is urea excreted from the body?

  Filtered out by the kidneys in urine
• What enzyme breaks down ethanol in the liver?

  Alcohol dehydrogenase
• What does catalase do in the liver?

  Splits hydrogen peroxide into oxygen and water
• Why is paracetamol broken down in the liver?

  To prevent toxicity to the liver and kidneys
• How does the liver help regulate blood glucose concentration?

  By metabolising insulin
• What are the functions of the liver in blood glucose regulation?

  • Converts excess glucose into glycogen
  • Stores glycogen granules
  • Releases glucose when blood levels fall
• What happens to haemoglobin from old red blood cells in the liver?

  It is broken down into bile pigments
• Where are bile pigments transported after being excreted from liver cells?

  To the gallbladder via the bile duct
• What are the key large parts of the liver structure?

  • Hepatic artery: supplies oxygenated blood
  • Hepatic vein: carries deoxygenated blood
  • Hepatic portal vein: brings nutrient-rich blood
  • Bile duct: transports bile to gallbladder
• What is the structure of liver lobules?

  • Composed of hepatocytes
  • Hepatocytes arranged along sinusoids
  • Sinusoids mix oxygen-rich and nutrient-rich blood
  • Kupffer cells ingest pathogens
  • Bile canaliculus links to bile duct
• What type of cells are hepatocytes?

  Liver cells
• What is the role of Kupffer cells in the liver?

  Ingest pathogens and foreign particles
• What is the function of the hepatic portal vein?

  Brings nutrient-rich blood from intestines
• What is the function of the bile duct?

  Transports bile to the gallbladder