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 Q: cardiac muscle  

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why cardiac muscle cant be tetanized? book says " bcaz duration of mechanical event is aprox equal to duration of refractory period". how does it prevent tetanizaation?


anybody please? mash? ruben ssss?? or an one else knows about it??


Mani, the way i understand is that well tetany basically repeated stimulation of muscle, more calcium is realeased from the SR and more tension and contraction due to build up of calcium. however, the way cardiac muscle is made is that the action potential has what is called an absolute refractory period during which no other action potential can be stmulated, hence the prevention of tetany. Please correct me if i am wrong.....


rida i ve got it clarified. in skeletal muscle the duration of action potential is much shorter than duration of mechanical event ie contaction. so this muscle can be restimulated by a new action potantial while it is still in the contaction phase due to previous action potential. This cant happen in cardiac muscle as the duration of action potantial is approx equal to duration of contraction. so when a cardiac muscle fibre comes out of refractory period, its mechanical event has already endedd and so summation of consecutive contractions cant take place. Got it??



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