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    It's question 1 C) i) about heart muscles action potentials (again)!!!

    Q: The contraction of a heart muscle cell requires an action potential to occur across its cell surface membrane. Action potentials propagate between neighbouring cells through the intercalated discs, which are freely permeable to ions. In this way, impulses, accompanied by contraction, spead through the muscle.
    Outline the events that occur when an area of cell surface mebrane undergoes an action potential. (5 marks)

    A: (only 1 of many listed)
    Resting potential is reduced or lowered / idea;

    EH?? Since when does it get lowered???
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    Well the potential is the relative difference in charges either side of the membrane. It is oringinally 70mV difference. It is -70mV because there is 'more negative charge' inside the membrane, but looking at it from outside the membrane there is less of the negative charge so it is positive in relation. This difference is reduced when the Na+ ion channels open and Na+ diffused in (facilitated diffision). Perhaps?

    This can only lead to one conclusion - even with a sketchy answer prepared by a tired and over-sunned three sciencer, this is merely a crap mark scheme.
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    (Original post by corkskrew)
    Well the potential is the relative difference in charges either side of the membrane. It is oringinally 70mV difference. It is -70mV because there is 'more negative charge' inside the membrane, but looking at it from outside the membrane there is less of the negative charge so it is positive in relation. This difference is reduced when the Na+ ion channels open and Na+ diffused in (facilitated diffision). Perhaps?

    This can only lead to one conclusion - even with a sketchy answer prepared by a tired and over-sunned three sciencer, this is merely a crap mark scheme.
    that is a very good answer i wouldnt have thought of it!! thanx and yes it is crap, they should have at least said in the mark scheme, difference is reduced instead of resting potential
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    (Original post by ecolier)
    It's question 1 C) i) about heart muscles action potentials (again)!!!

    Q: The contraction of a heart muscle cell requires an action potential to occur across its cell surface membrane. Action potentials propagate between neighbouring cells through the intercalated discs, which are freely permeable to ions. In this way, impulses, accompanied by contraction, spead through the muscle.
    Outline the events that occur when an area of cell surface mebrane undergoes an action potential. (5 marks)

    A: (only 1 of many listed)
    Resting potential is reduced or lowered / idea;

    EH?? Since when does it get lowered???
    Mm I've noticed this too, eg on here: http://www.s-cool.co.uk/topic_quickl...s=&ebl=&elc=13

    it says "Na+ therefore floods into the cytoplasm down the concentration gradient. //
    As this happens the membrane depolarises (this means that the resting potential of the cells starts to decrease)"
 
 
 
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