EXCITATION CONTRACTION COUPLING EXCITATION CONTRACTION COUPLING MOLECULAR BASIS
EXCITATION CONTRACTION COUPLING
EXCITATION CONTRACTION COUPLING
MOLECULAR BASIS OF MUSCULAR CONTRACTION SLIDING FILAMENT THEORY �Proposed by A. X. Huxely. �Process by which shortening of the contractile elements in the muscle is brought about by sliding of actin filament over the myosin filament �Formation of cross bridges between the haed of myosin and actin molecules
THE CROSS BRIDGE CYCLE
Mechanism of muscle relaxation �Increased sarcoplasmic calcium level during muscle contraction �Activation of Ca – Mg ATPase �Ca pumped back into the SR �Decreased sarcoplasmic Ca level �Detatchment of Ca from troponin �Cessation of actin myosin interaction �Muscle relaxation
ENERGY SOURCES FOR MUSCLE CONTRACTION �ATP present in sarcoplasm – suffice for 1 -2 sec �Creatine phosphate – suffice for 5 -8 sec �Glycolysis – suffiice for a min �Oxidation of cellular food stuffs – for longer periods
FATIGUE When repeatedly stimulated the muscle loses its excitability and gradually becomes less excitable and ultimates ceases to respond. This phenomenon is called fatigue SITE OF FATIGUE Intact body - CNS Isolated preperation - NMJ
RIGOR MORTIS �When muscle fibres are completely depleted of ATP & phosphocreatinine, they develop a state of rigidity called rigor. When this occurs after death the condition is called rigor mortis �Develops 4 -5 hrs after death and disappears in 40 hrs �All the muscles of the body are involved
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