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quick bio question

Discussion in 'MCAT Study Question Q&A' started by TypeSH07, May 15, 2008.

  1. TypeSH07

    TypeSH07 Junior Member 7+ Year Member

    Mar 20, 2004
    EK seems to say that protein digestion begins in the stomach and there is no absorption, but princeton material says there is NO digestion at all in the stomach and no absorption. Which is correct? Thanks.
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  3. Isoprop

    Isoprop Fascinating, tell me more 5+ Year Member

    Oct 15, 2007
    i believe digestion does happen in the stomach in the process you have described.
  4. RySerr21

    RySerr21 i aint kinda hot Im sauna 7+ Year Member

    Dec 22, 2007
    protein digestion begins in the stomach with HCl secreted from the parietal cells and pepsinogen secreted by the chief cells. Pepsinogen is inactive until it mixes with HCl and then becomes the active form pepsin. pepsins job is to break down proteins into peptides.

    EK is correct for the digesetion part. Both are correct as far as absorption....that begins in the small intestein, which is why they have villi to increase the surface area and absorb as much as possible.
  5. quiksilver87

    quiksilver87 10+ Year Member

    Feb 20, 2007
    You must understand though that MANY drugs (the weak acids) get absorbed through the stomach...Drugs that are weak bases will get absorbed in the intestine...
  6. TawMus

    TawMus 5+ Year Member

    May 18, 2008

    I think you may have read something wrong. I am also taking Princeton, and my book explicitly states that pepsin (which is activated from pepsinogen by HCl) breaks protein polypeptides into fragments. Proteins get furthur broken down in the small intestine by pancreatic peptidase and pancreatic zymogens (polypeptides = dipeptides & tripeptides). Afterwards brush border enzymes break down the dipeptides into monomers (amino acid). Amino acids are then transported into the intestinal epithelial cells by Na+/AA symport. Then uniporter transports AA into the interstitium. AAs eventually end up in the liver. Hope this helps.

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