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Physiology question

Discussion in 'Medical Students - MD' started by Omega00, Dec 4, 2008.

  1. Omega00

    Feb 1, 2008
    Likes Received:
    Medical Student

    I've several questions conerning the ECG if someone has time to help out.

    1) My teacher said that in the ventricles: last depolarization, first repolarization.
    He mentioned that it was due to the plateu of action potential happening earlier. How is that?

    2) How come T and P-waves can either be negative or positive? Shouldn't

    If you know any good websites explaining ECG, it would be great to post them too.

    I appreciate your input.
  2. howelljolly

    10+ Year Member

    Aug 30, 2007
    Likes Received:
    Resident [Any Field]
    Search for "EKG books" and other related topics on the SDN
    wikipedia tells you something about everything. you can start from there.

    I dont understand your first question

    Im going to take a stab at the second question, which I also dont understand. Waves are negative or positive depending on what Lead you are looking at. The Leads are in different locations (Einthoven's Triangle). The waves in that lead are positive where the electical impulse is moving toward, or in the direction of the lead. They are negative where the impulse is moving away from, or against that lead.

    T waves are almost always positive in all leads. The exceptions are Leads aVR, and sometimes V1. Negative T waves in the other leads make you think of bad things.

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