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Nerve MUSCLE PHYSIOLOGY

Nerve MUSCLE PHYSIOLOGY. Molecular Mechanism Of Muscle Contraction. Sliding filament mechanism Walk along theory Ratchet theory. Walk Along Theory. Interaction B/W Actin & Myosin. Walk Along (Ratchet) Theory. Relaxed & Contracted. NEUROMUSCULAR JUNCTION. Motor Unit. α - motor N.

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Nerve MUSCLE PHYSIOLOGY

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  1. Nerve MUSCLEPHYSIOLOGY

  2. Molecular Mechanism Of Muscle Contraction • Sliding filament mechanism • Walk along theory • Ratchet theory

  3. Walk Along Theory

  4. Interaction B/W Actin & Myosin

  5. Walk Along (Ratchet) Theory

  6. Relaxed & Contracted

  7. NEUROMUSCULAR JUNCTION

  8. Motor Unit α- motor N Single Motor Neuron & all Muscle Fibers it innervates constitute a single Motor Unit.

  9. NeuroMuscular Junction

  10. Release of Acetylcholine

  11. Ligand Gated Channel (Acetylcholine) Closed Open

  12. Safety factor for transmission at the Neuromuscular junction. • Fatigue of Neuromuscular Junction

  13. Myasthenia Gravis • 1 in every 20,000 persons. • Antibodies against acetylcholine receptors. • Autoimmune disease. • Muscle paralysis ---- inability of neuromuscular junction to transmit enough signals . • Neostigmine ---- anticholinesterase drug.

  14. Sarcoplasmic ReticulumT-Tubule & Longitudinal Tubule

  15. T Sarcoplasmic ReticulumT-Tubule & Longitudinal Tubule T L

  16. Sarcoplasmic Reticulum(T-tubule)DHP & Ryanidin Receptor (Hypothetical Model)

  17. A.P entering the Sarcoplasmic Reticulum causing release of Ca++ ions

  18. Excitation-Contraction coupling“The process by which the depolarization of the muscle fiber initiates contraction”

  19. Sequence of Events in contraction of Muscle • Stimulation of Motor Neuron. • Release of neurotransmitter (Acetylcholine) at Motor End-plate. • Binding of Ach to Nicotinic Receptors. • Increased Na+ conductance through Ach Channels • Generation of end-plate potential • Generation ofAction Potentialin Muscle Fiber

  20. Sequence of Events in Contraction • Inward spread of depolarization along T-Tubule- Sensing by DHP receptors & opening of Rayanidine receptors in terminal cisterns. • Release of Ca++ from terminal cistern of Sarcoplasmic Reticulum and diffusion to myofilaments • Binding of Ca++ to Troponin-C, uncovering Myosin binding on Actin filaments • Formation of Cross linkages between Actin & Myosin leading to sliding of thin on thick filaments, producing movement of Z-lines toward the centre

  21. Steps involved in Relaxation of Muscle • ATP attaches to Myosin head • Ca++ Pumped Back in Sarcoplasmic Reticulum. (Ca++ Mg++ ATPase Pump always On ) • Release of Ca++ from Troponin • Cessation of Interaction between Actin & Myosin filaments

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