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    Is single-unit smooth muscle innervated? My notes say it is myogenic - particular pacemaker cells that produce pacemaker potentials that spreads throughout the tissue via gap junctions. However, it doesn't say anything about autonomic innervation. If there is, I would assume that only the pacemaker cells recieve the innervation? And also that there is no discrete NMJ as is the case with multi-unit smooth muscle?
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    (Original post by nikk)
    Is single-unit smooth muscle innervated? My notes say it is myogenic - particular pacemaker cells that produce pacemaker potentials that spreads throughout the tissue via gap junctions. However, it doesn't say anything about autonomic innervation. If there is, I would assume that only the pacemaker cells recieve the innervation? And also that there is no discrete NMJ as is the case with multi-unit smooth muscle?
    I think you are talking about cardiac muscle, which is NOT smooth muscle!!!

    Smooth muscle is muscle that is controlled involuntarily by the autonomic system - e.g. muscles in the gut!!!

    Cardiac muscle is myogenic, which means that it can be without nervous innervation, but the rate at which it beats is controlled by the autonomic system. E.g. chronotrophic effects can affect the activity of the SA node - but the SA node causes contraction without needing nervous control.
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    (Original post by Revenged)
    I think you are talking about cardiac muscle, which is NOT smooth muscle!!!

    Smooth muscle is muscle that is controlled involuntarily by the autonomic system - e.g. muscles in the gut!!!

    Cardiac muscle is myogenic, which means that it can be without nervous innervation, but the rate at which it beats is controlled by the autonomic system. E.g. chronotrophic effects can affect the activity of the SA node - but the SA node causes contraction without needing nervous control.
    Nope i'm talking about smooth muscle.

    Single unit smooth muscle is myogenic (it is very different from cardiac, but does share features such as gap junctions and pacemaker cells), whereas multi-unit smooth muscle is neurogenic and each muscle cell functions and contracts independently.

    So I wanted to know if single-unit smooth muscle is innervated by the ANS? I know that multi-unit definitely is.
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    (Original post by nikk)
    Nope i'm talking about smooth muscle.

    Single unit smooth muscle is myogenic (it is very different from cardiac, but does share features such as gap junctions and pacemaker cells), whereas multi-unit smooth muscle is neurogenic and each muscle cell functions and contracts independently.

    So I wanted to know if single-unit smooth muscle is innervated by the ANS? I know that multi-unit definitely is.
    Ok... I thought you were talking about the heart because of pacemaker cells...

    I don't really know the answer... but remember that say with peristalsis in smooth muscle in the gut you also have the action of the enteric nervous system.
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    (Original post by Revenged)
    Ok... I thought you were talking about the heart because of pacemaker cells...

    I don't really know the answer... but remember that say with peristalsis in smooth muscle in the gut you also have the action of the enteric nervous system.
    Yep, I imagined that it must have some kind of nervous regulation...just wanted to check since my notes didn't mention it.
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    Yes they are innervated, by the enteric nervous system, although their myogenic nature means that these neurones will functional normally without external modulation.
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    (Original post by darkenergy)
    Yes they are innervated, by the enteric nervous system, although their myogenic nature means that these neurones will functional normally without external modulation.
    Don't you mean smooth muscle cells? :p:
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    crap, yeah. :p:
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    Erm, I don't know what you mean by single unit and multi unit, but here's some general smooth muscle info for what it's worth.
    Action potentials are only triggered by nervous (or hormonal) stimulation in a few cells - the pacemaker cells, which then transmit the APs throughout the tissue.
    The pacemaker cells undergo spontaneous depolarisation anyway, and it's the APs induced by spontaneous depolarisation that results in the natural tone of the muscle.
    But if there's external stimulation (eg nervous, or hormonal) then the amplitude of the spontaneous depolarisation can reach threshold resulting in more APs / greater frequency producing greater contraction. (just imagine a normal membrane potential vs time graph, but with stimulation the curve/graph is shifted up, ie so that the resting membrane potential is higher).

    And also that there is no discrete NMJ as is the case with multi-unit smooth muscle?
    I don't understand - I thought no smooth muscle cells possess NMJ, but only varicosities?
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    Yay I can study with you guys now *happy dance*

    We're looking at smooth muscle too

    K, I'm gonna go get some lunch but will look through my books to see how much the same our topics are.
 
 
 
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