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Axon diameter

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    Wondered why larger diameter of axon causes greater speed of transmission.



    MS: "Less leakage of ions from wider axon"

    Didn't quite get why less leakage.


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    With a larger diameter, there is less resistance. Hence increased conduction velocity

    This was posted from The Student Room's Android App on my GT-I9100
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    (Original post by 007007)
    With a larger diameter, there is less resistance. Hence increased conduction velocity

    This was posted from The Student Room's Android App on my GT-I9100
    Well I do understand that but I dind't understand the mark scheme ..
    I wouldn't get the mark by saying anything else apart from that marking point..there is no AVP in the mark schem
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    Ok, well then I imagine that the larger size of axon entails a relatively lower surface area for ions to leak...?

    Mark schemes are so restrictive

    This was posted from The Student Room's Android App on my GT-I9100
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    (Original post by 007007)
    Ok, well then I imagine that the larger size of axon entails a relatively lower surface area for ions to leak...?



    This was posted from The Student Room's Android App on my GT-I9100
    Larger size of axon gives lower SA?

    Mark schemes are so restrictive
    I know right..
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    The surface area to volume ratio would be lower i think. Thats such an obscure answer though
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    Surface area is basically the answer to every single question in biology
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    (Original post by arvin_infinity)
    Wondered why larger diameter of axon causes greater speed of transmission.



    MS: "Less leakage of ions from wider axon"

    Didn't quite get why less leakage.


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    Basically, this is my interpretation after researching it, as I was confused like you are. Essentially what books say is the larger the diameter the faster an impulse is conducted because less leakage and ions have less resistance to movement.

    I can only expand on my latter point. As the axon is wider, ions collide less when either being actively moved by the sodium-potassium pump or diffusing through the sodium or potassium channels, and so as there is less resistance (LIKE IN GEL ELECTROPHORESIS) the ions move faster, meaning adjacent regions depolarise at a faster rate i.e. impulse conducted at higher rate

    Thats my detailed reason ))
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    Is it a wjec question?


    This was posted from The Student Room's iPhone/iPad App

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Updated: June 18, 2012
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