Liver

• What are liver cells called?

  Hepatocytes
• It is essential that the liver has a good supply of blood
• The liver plays an important role in excretion – it breaks down harmful substances as well as toxic waste. It converts the substances into less harmful forms, ready to be disposed of.
• The liver is supplied with blood from two sources:

  • Hepatic artery
  • Hepatic portal vein
• Label the diagram:

  1. Aorta
  2. Vena Cava
  3. Hepatic Artery
  4. Hepatic Vein
  5. Liver
  6. Gall Bladder
  7. Bile Duct
  8. Diaphragm
  9. Hepatic Portal Vein
  10. Pancreas
  11. Small Intestine

  
• Define Hepatic Artery:

  The main artery which supplies the liver tissue with oxygenated blood from the heart for aerobic respiration
• Oxygenated blood travel through which two vessels to go to hepatocytes?

  • aorta
  • hepatic artery
• Define Hepatic Portal Vein:

  The main vein which carries deoxygenated blood rich in nutrients from the small intestine and pancreas to the liver
• Blood that travels through the hepatic portal vein has uncontrolled concentrations of various products of digestion from the intestines, these will contain toxic compounds that may have been adsorbed
• Blood leaves the liver via what vessel?

  Hepatic vein
• The hepatic vein rejoins the vena cava and the blood returns to the body's normal circulation
• What does the liver secrete?

  Bile
• What tube transports bile from the liver to the gall bladder?

  Bile duct
• Where is bile stored?

  Gall bladder
• Hepatocytes are arranged into cylindrical lobules
• Define Hepatic Vein:

  The main vein which takes deoxygenated blood rich in the products of liver metabolism away from the liver back to the heart
• Bile contains some excretory products such as bile pigments like bilirubin
• Outline the functions of the liver:

  • to control blood glucose/ lipid levels
  • deaminates excess amino acids
  • to store vitamins/ iron/ glycogen
  • to breakdown hormones/ erythrocytes
  • detoxifies alcohols and chemicals
  • to synthesis erythrocytes in the fetus/ bile/ plasma proteins/ cholesterol
• Branches of the hepatic artery and hepatic portal vein that run between and parallel to the lobules are known as interlobular vessels
• Each liver lobule is a shape as a hexagon with microvilli on their surface, they consist of hepatocytes and centred around a central hepatic vein as known as the intralobular vessel
• Define Sinusoid:

  A chamber lined with liver cells where the blood of the hepatic artery and hepatic portal vein mix to exchange substance between the cells.
• Which branches of the major tubes that run between and parallel to liver lobules are referred to as the Portal Triad?

  • Hepatic Artery
  • Hepatic Portal Vein
  • Bile duct
• Define Kupffer Cells:

  A specialised macrophage located in the sinusoids of the liver to breakdown pathogens, dead cells and recycle old erythrocytes and leukocytes
• The blood from which vessel is most likely going to contain foreign matter in which the kupffer cell will breakdown in the sinusoid?

  hepatic portal vein
• The kupffer cell breaks down haemoglobin into bile pigment such as bilirubin which is excreted in faeces
• The bile canaliculi join together to form the bile duct
• What is described as the intralobular vessel?

  the branch of a hepatic vein in the centre of liver lobules
• Label the diagram:

  1. Hepatocytes
  2. Sinusoid
  3. branch of hepatic artery
  4. branch of hepatic portal vein
  5. bile duct
  6. bile canaliculus
  7. kupffer cell
  8. hepatic vein / intracellular vessel
  9. portal triad

  
• The glycogen forms granules in the cytoplasm of hepatocytes. These granules can be broken down to release glucose into the blood as required.
• Name the two enzymes that liver cells contain:

  • Catalase
  • Cytochrome P450
• Catalase break down hydrogen peroxide into oxygen and water
• Cytochrome P450 is a group of enzymes used to break down drugs and used in other metabolic reactions such as electron transport during respiration

  Their role of metabolising drugs can interfere with other metabolic roles and cause the unwanted side effects of some medicinal drugs
• Why do some people suffer side effects that others do not experience from drugs?

  Cytochrome P450 enzymes show a lot of variations between individuals

  As they break down different drugs, various end products are produced
• In what organ is alcohol broken down in the body?

  liver
• Ethanol is broken down in hepatocytes by what enzyme?

  Ethanol dehydrogenase
• What type of drug is alcohol?

  Depressant
• Ethanal is broken down in the liver cells by what enzyme?

  Ethanal dehydrogenase
• As alcohol is broken down in the hepatocytes, it releases hydrogen atoms that combined with a coenzyme called NAD to form reduced NAD. This is required to oxide and breakdown fatty acids for respiration.
• Alcohol contains chemical potential energy which can be used for respiration
• Name this process:

  Detoxification of alcohol