D.2 Liver

• State the name of the blood vessel through which lactate from muscles reaches the liver: Hepatic artery
• Functions of the liver:

  1. detoxification
  2. production/secretion of bile
  3. conversion of cholesterol to bile salts; synthesis and regulation of cholesterol
  4. production of plasma proteins
  5. nutrient storage
  6. glucose regulation in blood
  7. deamination/transamination; conversion of ammonia to urea
• Breakdown of RBC:

  1. haemoglobin taken up by Kupffer cells
  2. broken down into heme group and globin group
  3. globin hydrolysed into amino acids
  4. iron removed from heme group, binds to transferrin and is transported to bone marrow
  5. heme group broken down to form bilirubin which is converted into bile, to be stored in the gall bladder, and secreted in the duodenum
• Use of PPI in treatment:

  1. Proton pump is a transmembrane protein
  2. Proton pump inhibitors (PPI) binds to the proton pump
  3. H+ is not sent into the stomach lumen - reduction of gastric acid production
  4. increase of pH in stomach
  5. relieve symptoms of acid reflux/gastritis/ulcers
• Circulation of blood through liver tissues:

  1. hepatic artery carries oxygenated blood (from the aorta)
  2. hepatic portal vein carries (deoxygenated) blood from digestive tract
  3. blood from hepatic portal vein and hepatic artery mixes
  4. flows through sinusoids
  5. hepatic vein carries blood away from liver/to heart
• Increased risk to CHD

  1. high cholesterol/LDL
  2. hypertension
  3. obesity/lack of exercise/smoking
  4. genetic predisposition
• Explain how the normal production of bile pigments changes with the development of jaundice

  Normal production:

  1.  red blood cells/erythrocytes/hemoglobin broken down «in the liver»
  2. hemoglobin/heme «from red blood cells» is converted to bilirubin/bile pigment
  3. bilirubin/bile pigment transferred to bile and «normally» eliminated in the feces

  Change with jaundice:

  1. «in jaundice» liver does not excrete/eliminate bilirubin/bile pigment
  2. caused by immaturity/dysfunction/disease «of the liver» OR blockage of bile ducts OR increase in RBC breakdown
  3. thus bilirubin accumulates in the blood causing jaundice
• Function of the hepatic portal vein:

  1. takes blood from intestine, spleen, pancreas, stomach to the liver
  2. carries digested nutrients
  3. prevents glucose from entering the general circulation
  4. helps maintain osmotic potential of blood
  5. allows toxins to be removed
• Compare capillaries and sinusoids

  1. Sinusoids have fenestrations/discontinuous endothelium; capillary endothelium is continuous/does not contain fenestrations
  2. Kupffer cells are located inside sinusoids but not in capillaries
  3. Sinusoids are larger in diameter than capillaries
• Causes and consequences of jaundice:

  Cause: Hepatitis / liver cancer / cirrhosis / parasite infection / excess production of bile pigments/bilirubin / blocked bile ducts / gall stones

  Consequence: yellowing/discoloration of skin/sclera/white of the eye / dark urine / grey feces / brain damage in infants 
• Advantages of the blood supply from the pancreas passing directly into the liver:

  1. the liver can respond quickly to hormones made by the pancreas
  2. the pancreas secretes insulin / glucagon into the blood «traveling directly to the liver»
  3. «the hormones released by the pancreas» stimulate the liver to store / release glucose
  4. allows rapid regulation of blood glucose levels