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Water reabsorption

Discussion in 'MCAT Study Question Q&A' started by wannabedocta, 04.18.08.

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  1. wannabedocta

    wannabedocta 7+ Year Member

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    Where does the most water reabsorption take place?? A practice test solution says small intestine, while another source says colon :confused:
     
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  3. eikenhein

    eikenhein 10+ Year Member

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    Under normal circumstances most resorption occurs in the small intestine, but the greatest *potential* for resorption occurs in the large intestine.
     
  4. BloodySurgeon

    BloodySurgeon Moderator Emeritus Lifetime Donor 7+ Year Member

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  5. Kaustikos

    Kaustikos Archerize It 7+ Year Member

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    Don't you just love prefixes?:D I've never heard of water absorption taking place mostly in the small intestine, I always thought it was the colon and Kaplan says so, as well as audio osmosis. Unless this is a trick question...or i'm studying wrongly made material.:mad:
     
  6. shmrshines

    shmrshines nerd in hot girl clothing 2+ Year Member

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    I remember this from nursing school, so take it for what you will, but I'd go with the large intestine. This might sound gross but I always remember it like this: The longer you hold your poop the more water gets reabsorbed into your system= the harder it is coming out.(generally speaking)
     
  7. wannabedocta

    wannabedocta 7+ Year Member

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    Yea, I had always thought the colon was the site of water reabsorption. weird.
     
  8. BloodySurgeon

    BloodySurgeon Moderator Emeritus Lifetime Donor 7+ Year Member

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    :confused: If I'm not missing something, the colon is part of the large intestine. And both are acceptable answers for where the water/electrolyte reabsorption is taking place. :confused:
     
  9. eikenhein

    eikenhein 10+ Year Member

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    The GI tract does have a significant amount of secretion and resorption, in addition to absorption.
     
  10. Kaustikos

    Kaustikos Archerize It 7+ Year Member

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    I f**king hate that word.:laugh:

    So, is it reabsorption or absorption?
     
  11. BloodySurgeon

    BloodySurgeon Moderator Emeritus Lifetime Donor 7+ Year Member

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    Technically reabsorption is the act or process of absorbing again, as the selective absorption by the kidneys of substances (glucose, proteins, sodium, etc.) already secreted into the renal tubules and their return to the circulating blood. The intestines are the first line of absorption (unless its something the body secreted into the lumen such as Ca2+ from the bones), therefore everything else will be reabsorption... but I see it used both ways and I don't think it really matters.

    If it is going to your circulating blood its (re-)absorption
     
  12. tweaked17

    tweaked17 7+ Year Member

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    I hope this doesn't add to anyone's confusion, but the practice test solution is right.

    This is often taught wrong or misconstrued, but the majority of water absorption (or reabsorption) occurs in the small intestine; however, the main role of the colon is concentration of excretion through water and salt reabsorption. This does not mean the majority of water is (re)absorbed here.
     
  13. Heyeon

    Heyeon Heyeon 5+ Year Member

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  14. BloodySurgeon

    BloodySurgeon Moderator Emeritus Lifetime Donor 7+ Year Member

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    hmm.. that makes more sense. The small intestine should be where most absorption takes place and the large intestine will play a major role in water in examples like diarrhea and constipation whenever there is a low or high osmotic pressure.
     
  15. BloodySurgeon

    BloodySurgeon Moderator Emeritus Lifetime Donor 7+ Year Member

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    Quote from your website:

    "The large intestine receives the liquid residue after digestion and absorption are complete."

    "Reabsorption of water is the chief function of the large intestine."


    I agree with tweaked with his answer. I jumped into my answer because I see water absorption and immediately thought colon and I'm sure you've done the same.

    And on a side note, Eikenhein is correct "The GI tract does have a significant amount of secretion and resorption, in addition to absorption" and you could say it has both absorption and reabsorption.
     
  16. phospho

    phospho SDN Lifetime Donor Lifetime Donor 7+ Year Member

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    thank you:luck:
     
  17. Zerconia2921

    Zerconia2921 Bring your A-game! 2+ Year Member

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    Water gets reabsorbed in the colon ie large intestines. Small intestine depends which part is were carbs, fats, amino acids get broken down into their respectable monomers.
     

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