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How do proteins get into the blood stream?

  1. Nov 19, 2013 #1
    Hi there,

    So I'm asking this in reference to the injection of insulin, which is commonly done subcutaneously (in the hypodermis, a fatty part of skin). Now I know proteins usually get into the blood when digested through the stomach/intestines - but I was wondering how they manage to get into the blood when injected into muscles/fat? I know there are capillaries pretty much everywhere, but from what I've researched proteins are too large to get through capillary walls.

    That begs the question then, how do proteins manage to get into the blood stream when injected? I can't really envisage large capillaries, because surely they'd have huge holes in them or whatever to allow large proteins like insulin in. Any help on this one?

    Cheers
     
  2. jcsd
  3. Nov 19, 2013 #2
    Lymphatic capillaries are permeable to proteins. They lack tight intercellular junctions and are permeable to many kinds of molecules.

    http://jcb.rupress.org/content/50/2/300.full.pdf
     
    Last edited: Nov 20, 2013
  4. Nov 20, 2013 #3
    Ah thanks a ton, precisely what I was looking for.
     
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