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Can someone please explain to me what the CHLORIDE SHIFT IS?

Discussion in 'MCAT Discussions' started by EECStoMed, 07.29.07.

  1. EECStoMed

    EECStoMed Persistence > Intel

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    Can someone please explain to me what the CHLORIDE SHIFT IS? I've listened to it about 5 times on audio osmosis but I still don't get it. Can someone using layman term explain to me what exactly it is?
  2. axp107

    axp107 UCLA 09': Italian Pryde

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    It's to balance charges in a blood cell...

    when you take in CO2, it gets converted into H2CO3.. then HCO3-

    EDIT:

    HCO3- moves out of the blood cell into the plasma since its concentration is low in the plasma...

    to balance the removal of -ive charge, a Cl- moves in
  3. EECStoMed

    EECStoMed Persistence > Intel

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    Umm, I think it's the other way around. According to audio osmosis, chloride shift occurs when CO2 is released from the blood. I think it's because some of CO2 is stored in the RBC as bicarbonate and is converted back to CO2 (which constitutes) use of bicarbonate within the RBC. So more bicarbonate enters the RBC as it's being used up to be converted into CO2. Am I on the right track?
  4. axp107

    axp107 UCLA 09': Italian Pryde

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    Actually it happens both ways.. Cl- can move in or out.. depending on whats happening..


    At veins: Cl- moves in

    At lungs: Cl- moves ou

    here's a post by corbis 11:

    "CO2 moves from cells(which is from metabolism) into the blood down a pressure difference gradient. The CO2 moves into the red blood cell and will react with the RBC's carbonic anhydratase to form carbonic acid which reversibly converts into HCO3- and H+. The HCO3- will move out into the blood plasma(since there is a conc. diff. of which HCO3- is greater in the RBC) while a chloride ion moves into the RBC for charge conservation. When the blood gets to the lungs the alveolar PCO2 is lower than the blood so the reverse reactions all occur(Cl-moves out RBC & HCO3- moves into RBC where it converts back to carbonic acid and on to water and CO2) while the CO2 is unloaded to the alveoli to be expired."
  5. EECStoMed

    EECStoMed Persistence > Intel

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    According to corbis11:

    At the lungs: Cl- is supposed to move out and at the veins, move in.
  6. axp107

    axp107 UCLA 09': Italian Pryde

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    yeah

    drawing a picture helps.. makes much more sense that way
  7. Hyperstudyosis

    Hyperstudyosis

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    Drawing a picture will really really help you to be able to visualize it. Basically, in internal respiration, oxygen dissociates from oxyhemoglobin and diffuses into tissue cells. Carbon dioxide is going in the opposite direction, from the tissue cells into systemic capillary blood. Some of the carbon dioxide binds with hemoglobin to form carbamino hemoglobin, while some carbon dioxide combines with water to form carbonic acid. This carbonic acid then dissociates into bicarbonate ions and hydrogen ions. The bicarbonate ion leaves the red blood cell and goes into the plasma and in order to maintain the electrical balance, a chloride ion enters the red blood cell (since both have a negative charge). This is the chloride shift.

    In external respiration, when carbon dioxide is exhaled, hemoglobin inside the red blood cells unload carbon dioxide and pick up oxygen from alveolar air. As oxygen combines with hemoglobin, thi scauses hydrogen ions to be released from hemoglobin. Bicarbonate ions from the plasma come into the red blood cell and bind with the hydrogen ions to form carbonic acid. This carbonic acid then dissociates into water and carbon dioxide and carbon dioxide diffuses from the blood into alveolar air so that it can be exhaled. But when the bicarbonate ion enters the red blood cell to bind with the hydrogen ion, a chloride ion must leave the red blood cell in order to maintain electrical balance. This is the reverse chloride shift and it is basically a reversal of everything that happened in internal respiration with the chloride shift.

    Hope this helps some.

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