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proteins....

Discussion in 'Medical Students - MD' started by anum, Mar 28, 2007.

  1. anum

    anum Junior Member
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    no proteins can be absorbed without being digested to amino acids. But the immunoglobulins that a child gets from mother during lactation are absorbed .immunoglobulins are proteins plus are they not at risk of being digested in the stomach.i need help?is it concerned with enzymes.as none are present to digest immunoglobulins, but still how are they absorbed.
     
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  3. AggieJohn

    AggieJohn Senior Member
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    I believe some proteins can be absorbed without being fully digested.
     
  4. 45408

    45408 aw buddy
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    I don't see how - you only have transporters for amino acids, di- and tri-peptides in the small intestine. I am curious for the answer though.
     
  5. anum

    anum Junior Member
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    under physiological Ph amino acids are charged. it depends on the molecular weight and the charge of the object that has to be transported across the menbrane.the tranport chanels are of specific configuration to accept only the smaller objects.protiens for that matter have a very high molecular weight.it is practically impossible to shuttle 'em across the bilipid membrane.Even the fenestrated capillaries donot permit the albumin and such proteins to cross the podocytes.is it not?
     
  6. acute2

    acute2 Abort Retry Ignore
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    Dietary proteins must be digested. I agree with that, even in infants. Proteins in mother's milk are acted upon by aminopeptidases. But such is not the case with colostral immunoglobulins.

    In infants, colostral immunoglobulins are absorbed as such by the enterocytes by formation of tubules at the base of the apical microvilli. These tubules pinch off in the cell to form small vesicles that can transport the contents to the basolateral membrane and release their contents into the extracellular space. From there the macromolecules can be absorbed into the blood.

    Why cleave immunoglobulins into its components? Immunoglobulin will be useless as an immuno-agent if you break it. :)
     
  7. Brown429

    Brown429 Junior Member
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    I am guessing Transcytosis....? That is what I learned in undergrad...?
     
  8. acute2

    acute2 Abort Retry Ignore
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    Brown429, correct! :thumbup:
     
  9. Critical Mass

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    This thread makes me think of the end of "Grapes of Wrath," but I don't think that the IgA would survive in an adult stomach.

    I agree with the above. If you remember those baby formula commercials with the broken-down peptides. It confirms that peptidases, etc. aren't mature in miniature humans.
     
  10. indo

    indo Feed me a stray cat
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    Is that the one where the man breast feeds the baby?
     
  11. Critical Mass

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    I thought that it was a woman who had just given birth, and wasn't she nursing a starving homeless man or something?

    Anyway, I think that her colostrum supply had been pretty much spent at that point.
     
  12. anum

    anum Junior Member
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    yes that is convincing...but before reaching the enterocytes the immunoglobulins have to pass the stomach.
    the acidic ph ,gastric juice and the whole protein digesting environment.How do Immunoglobulins survive that?
     
  13. acute2

    acute2 Abort Retry Ignore
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    Though it is true that the acidic pH, gastric juice, etc will digest immunoglobulins, please consider also that a newborn does not have a mature digestive system yet. It has never really learned to completely process food yet. By way of compensation, as if mother nature has thought of this already, the digestive system of neonates allows the absorption of macromolecules temporarily. These macromolecules are absorbed in the ileum. Now in the case of colostral immunoglobulins, absorption happens only a short period of time after birth--the time of baby's first suck. Absorption is initially high then declines gradually just so to accomodate the infusion. From there, intestinal absorption of the immunoglobulins eventually will no longer be accomodated. This period is known as the "time of closure".

    Same reason why mothers are encouraged to breastfeed the baby as soon as both become ready for their first mother-child intimacy interaction. They call it "rooming-in". :)
     
  14. SanDiegoSOD

    SanDiegoSOD Milk was a bad choice
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    I'm guessing most people posting here either 1. arent med students or 2. slept through immuno. :smuggrin:
     
  15. acute2

    acute2 Abort Retry Ignore
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    SanDiegoSOD, their questions and arguments are okay for purposes of academic discourse. They asked because they want to know and discuss, or interact with other sdn forum members. It does not mean that they or the others, (myself and even you included) know more or know less about biochemistry and or immunology. Sometimes, they just wanna know if others have the same answer or understanding. Or, others might be asking the same question.. Just let people be, let us all learn together :)
     
  16. Critical Mass

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    I have to speak up here, acute2...

    Your avatar is totally freaking me out. :scared:
     
  17. acute2

    acute2 Abort Retry Ignore
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    To each his own avatar, Critical Mass. Thanks ;)
     
  18. anum

    anum Junior Member
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    i am a second year medical student...am curious to know! its not a rule that everyone has to have 100 percent knowledge ,the subjects i am dealing with at the moment are physiology,biochemistry and anatomy .... thanks to people like you these questions are rarely asked in the class!:thumbdown:
     
  19. anum

    anum Junior Member
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    :)

    Thanks:thumbup::)
     
  20. AggieJohn

    AggieJohn Senior Member
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    I have to agree.
     
  21. indo

    indo Feed me a stray cat
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    Oh, well, there is a good chance I skipped or slept through that class in high school. I do remember some book that was controversial because a man breast feeds a baby. I dunno.
     
  22. 45408

    45408 aw buddy
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    3. haven't taken immuno yet
     
  23. Critical Mass

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    Speaking of avatars and milk, does your milkshake bring all the boys to the yard?
     
  24. RokChalkJayhawk

    RokChalkJayhawk Muck Fizzou
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    Is that really a woman Critical Mass? Looking at her hands I'm not quite so sure.

    It also looks like someone's Myspace photo.
     
  25. Critical Mass

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    Well I didn't get it off of myspace, but I can't find the link anymore. I had that problem with the last avatar too.

    Back onto the thread topic, I definitely think that this girl gets her daily protein allowance.
     

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