BIOL 404-Exam 4-GI 9

  1. How much iron is ingested daily?
  2. How much of the iron ingested is absorbed daily?
  3. When does iron absorption increase?
    With need (hemorrhage, growth and pregnancy)
  4. What type of absorption mechanism is used for iron and heme?
    Carrier-mediated transporters on the brush border
  5. What regulates iron absorption?
    enterocyte ferritin levels
  6. Why are enterocyte ferritin levels important?
    They regulate the absorption of iron
  7. What is the most readily absorbed ferrous state?
  8. What state is most dietary iron?
    FE3+ state
  9. What is an example of a substance that can create a soluble complex with Iron?
  10. How can you increase the solubilty of Iron?
    Gastric acid solubilizes iron allowing soluble ascorbate complexes to increase absorption
  11. Apoferritin globular protein of 224 sub-units surrounds and iron micelle of what size?
    Micelle with up to 4500 iron atoms
  12. Describe the process of Iron uptake:
    • Iron binds to iron binding protein
    • Taken into cell
    • Binds to Ferritin
    • Some is released into the interstitum
    • Enters the blood
  13. Higher ferritin levels min the cell mean what to iron absorption?
    Less iron is absorbed into the blood
  14. How is the iron binding protein and iron complex absorbed into the cell?
    Mediated transport system
  15. Only about ______% of ingested iron is absorbed into the bloodstream.
  16. What intracellular component regulates the amount of iron absorbed?
    Intracellular ferritin
  17. What happens to most of the iron bound to ferritin?
    It is released back into the intestinal lumen when the intestinal cells disintegrate
  18. How often do cells disentigrate?
    Every 5 days
  19. Where is most iron excreted?
    In the feces
  20. Under conditions of iron need, how is more iron absorbed?
    Less ferritin is synthesized so that more iron is absorbed into the bloodstream
  21. Under what conditions would you expect Ferritin levels to be low?
    When iron need is increased
  22. The presence of food or chye in the GI can cause what three process to change?
    • Secretion of digestion juices
    • Motility
    • Blood flow to the tissues
  23. What are the general functions of the GI tract?
    Supply nutrients to the body and to remove non digestible material
Card Set
BIOL 404-Exam 4-GI 9
BIOL 404-Exam 4-GI 9