LIVER functions 0.0 / 5 ? BiologyCellular processes and structureA2/A-levelOCR Created by: Steff06Created on: 12-03-16 14:26 What processes is the liver involved in? Bile, amino acids are converted to glucose, protein, lipid and carbohydrate metabolism, deamination/transamination. 1 of 30 Last question continued... Produces urea, stores vitamins and minerals, synthesis and regulation of cholesterol, breaks down hormones. 2 of 30 What 3 blood proteins are produced in protein metabolism? Fibrinigen, albumin and globulins. 3 of 30 Define transamination Conversion of 1 amino acid to another. 4 of 30 Define deamination Removing excess amino acids. 5 of 30 What is the production of urea linked to? Deamination 6 of 30 What cannot be stored in the liver? Excess amino acids. 7 of 30 What do excess amino acids undergo and what are they converted into? Deamination. They are converted into glucose and then triglycerides. 8 of 30 What happens to proteins during digestion? They are hydrolysed into amino acids and transported to the liver along the hepatic portal vein. 9 of 30 What is urea produced from and where is it transported to? Excess amino acids. Transported to kidneys where it is excreted as urine. 10 of 30 What are the 3 stages of the ornithine cycle? Ornithine, citruilline, arginine. 11 of 30 What enters and leaves during the ornithine stage? Ammonia and CO2 in, H20 out. 12 of 30 What enters and leaves during the citruilline stage? Ammonia in, H20 out. 13 of 30 What enters and leaves during the arginine stage? H20 in, urea out. 14 of 30 What happens in the ornithine stage? Amino group and hydrogen is removed to form ammonia and a keto acid. 15 of 30 Describe the citruilline stage Highly toxic ammonia enters ornithine cycle and is converted to urea. Excess amino acids cannot be stored and undergo deamination in the liver. 16 of 30 Describe the arginine stage Keto acid either enters respiratory pathway and generates ATP or is converted into carbohydrates/fats. 17 of 30 What is ammonia converted into and where does this go? Converted into less toxic and less soluble urea. Urea travels to kidneys. 18 of 30 How can detoxification take place? By oxidation, reduction or methylation of toxins. 19 of 30 What can go through detoxification? Alcohol, antibiotics and steroid hormones. Often by action of enzymes. 20 of 30 Where and how is alcohol broken down and what is the product? Broken down in hepatocytes by enzyme ethanol dehydrogenase to produce ethanal. 21 of 30 What happens to ethanal and what is the product? Ethanal further dehydrogenated by ethanal dehydrogenase into ethanoate. 22 of 30 What does ethanoate combine with and what does this produce? Combines with coenzyme A to produce acetyl coenzyme A. 23 of 30 Where does this coenzyme A end up and what is produced? It enters the krebs cycle and reduced NAD + ATP is reduced. 24 of 30 Why is NAD required? To oxidise and break down fatty acids for use in respiration. 25 of 30 What are fatty acids converted back into and where are they stored? Converted back into lipids and stored in hepatocytes. 26 of 30 What effect does this have on the liver? It enlarges the liver which can lead to alcohol related hepatitis or cirrhosis. 27 of 30 What happens if there is too much alcohol? NAD can't break down fatty acids so they start to build up which destroys the structure of the liver. 28 of 30 What does cirrhosis cause? An increase in ammonia concentration which can cause major damage to the central nervous system. 29 of 30 What are damaged hepatocytes replaced by and what happens to the blood supply? Fibrous tissue and blood supplies structure is lost. 30 of 30
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