Excitation contraction coupling<br />Transmission of action potential along transverse tubules (T tubules)<br />T tubules ...
Neuromuscular transmission<br />Action Potential through motor nerve fiber<br />Axon Terminal<br />Opening of Voltage gate...
 When the impulses are transmitted from nerve to the muscle, a series of events occur in the neuromuscular junction:</li><...
Exciting Contraction Coupling<br />
Neuromuscular Transmission <br />Nerve impulse reaches end of axon<br />Ca channels open<br />Release of Ach into synaptic...
Generation of Action potential<br />Resting sarcolemma is polarized<br />Outside the cell is positive (predominant extrace...
Stimulation Ach binding to Ach receptors on sarcolemma<br />Ion gates open (Na rushes into cell and K rushes out of cell<b...
Depolarization<br />Loss of state of polarity<br />Loss of negative membrane potentials<br />Nerve stimulus is strong enou...
Generation of Action Potential<br />
Generation of Action Potential<br />
Sliding Filament <br />Explains the relationship between thick and thin filaments as contraction proceeds<br />The influx ...
Sliding Filament <br />The binding of myosin to actin<br />Myosin head bind to actin site and forming cross bridge<br />Mo...
Sliding Filament <br />Disconnecting Myocin head from Actin<br />ATP binds to the myosin head disconnecting from actin<br ...
Sliding-Filament Mechanism<br />
Sliding-Filament Mechanism<br />
CONTRACTION<br />ISOTONIC CONTRACTIONS CAUSES <br />THE MUSCLE LENGTH TO  CHANGE AND THE LOAD TO MOVE<br />USED IN<br />WA...
CONTRACTIONS<br />
CONTRACTIONS<br />ISOMETRIC CONTRACTIONS<br />TENSION BUILDS TO THE MUSCLE’S<br />CAPACITY, BUT THE MUSCLE<br />NEITHER SH...
CONTRACTIONS<br />
MUSCLE TWITCH<br />A single rapid contraction in response of muscle to a stimulus<br />Muscle fiber contracts and then rel...
MUSCLE CONTRACTION<br />THERE ARE THREE PHASES:<br />LATENT PERIOD<br />PERIOD OF CONTRACTION<br />PERIOD OF RELAXATION<br />
LATENT PERIOD<br />First few seconds following stimulation<br />Increase in muscle tension<br />Ca release<br />Cross brid...
PERIOD OF CONTRACTION<br />Cross bridges are active<br />Sarcomere shorten<br />
PERIOD OF RELAXATION<br />Re entry of Ca to Sarcoplasmic Reticulum<br />Muscle tension decreases to zero<br />Cross bridge...
GRADED MUSCLE RESPONSES<br />Variations in the degree of muscle contraction<br />Three ways muscle contraction are graded<...
Degree of muscle stretch (The Effect of Sarcomere Length on Tension)<br />Amount of tension (force) generated by the muscl...
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Lec26

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Lec26

  1. 1. Excitation contraction coupling<br />Transmission of action potential along transverse tubules (T tubules)<br />T tubules action potentials caused release of Ca ions inside the muscle fiber.<br />Ca ions caused contraction<br />Overall process called Excitation Contraction Coupling <br />
  2. 2. Neuromuscular transmission<br />Action Potential through motor nerve fiber<br />Axon Terminal<br />Opening of Voltage gated Calcium channels<br /><br />Entry of Calcium ions from Extracellular fluid<br /><br />Opening of vesicles & release of Ach<br /><ul><li>The function of neuromuscular junction is to transmit the impulses from the nerve to the muscle.
  3. 3. When the impulses are transmitted from nerve to the muscle, a series of events occur in the neuromuscular junction:</li></ul>Release of acetylcholine <br />Action of acetylcholine <br />Binding with receptors <br />Miniature end plate potential <br />Destruction of acetylcholine <br />Synaptic cleft<br />Passage of Ach<br />Postsynaptic membrane<br />Binding of Ach with Receptor and formation of <br />Ach-Receptor complex<br /><br />Opening of the ligand gated sodium channels <br />& entry of sodium ions from ECF<br /><br />Development of end plate potential<br />Muscle Fiber<br />Generation of Action Potential<br /><br />Excitation contracting coupling<br /><br />Muscular contraction<br />
  4. 4. Exciting Contraction Coupling<br />
  5. 5.
  6. 6. Neuromuscular Transmission <br />Nerve impulse reaches end of axon<br />Ca channels open<br />Release of Ach into synaptic cleft<br />Diffusion of Ach across the cleft<br />Attachment of Ach to ach receptors on sarcolemma<br />Opening of Na channels which initiates depolarization of sarcolemma <br />Development of end plate potential<br />Generation of action potential<br />The action potential causes the release of Ca ion from the terminal cisternae<br />Muscular contraction<br />
  7. 7. Generation of Action potential<br />Resting sarcolemma is polarized<br />Outside the cell is positive (predominant extracellular ion is Na)<br />Inside the cell is negative (predominant intracellular ion is K)<br />
  8. 8. Stimulation Ach binding to Ach receptors on sarcolemma<br />Ion gates open (Na rushes into cell and K rushes out of cell<br />Cells interior becomes less negative<br />Depolarization <br />Generation of Action potential<br />
  9. 9. Depolarization<br />Loss of state of polarity<br />Loss of negative membrane potentials<br />Nerve stimulus is strong enough<br />Action potential is generated from neuromuscular junction across the sarcolemma in all directions<br />Action potential separates over cell surface<br />Generation of Action potential<br />
  10. 10. Generation of Action Potential<br />
  11. 11. Generation of Action Potential<br />
  12. 12. Sliding Filament <br />Explains the relationship between thick and thin filaments as contraction proceeds<br />The influx of Ca ion, triggering the exposure of binding sites on actin<br />The Action potential brings about the release of Ca ion from the terminal cisternae<br />Ca ion binds to the troponin, causing change in conformation of the troponin tropomyosin complex<br />This conformation changes exposes the binding site on actin<br />
  13. 13. Sliding Filament <br />The binding of myosin to actin<br />Myosin head bind to actin site and forming cross bridge<br />Movement of thin filament<br />Release of ADP and Pi<br />The myosin cross bridge pulls the thin filament inward toward the centre of sarcomere<br />
  14. 14. Sliding Filament <br />Disconnecting Myocin head from Actin<br />ATP binds to the myosin head disconnecting from actin<br />Repositioning of the myosin head<br />The release of myosin head trigger the hydrolysis of ATP molecule into ADP and Pi<br />Energy is transferred from ATP to the myosin head <br />Removal of Ca ion <br />Ca ion transported back into the sarcoplasmic reticulum<br />Troponin - tropomyosin complex covers the binding sites on Actin <br />
  15. 15. Sliding-Filament Mechanism<br />
  16. 16. Sliding-Filament Mechanism<br />
  17. 17. CONTRACTION<br />ISOTONIC CONTRACTIONS CAUSES <br />THE MUSCLE LENGTH TO CHANGE AND THE LOAD TO MOVE<br />USED IN<br />WALKING<br />MOVING ANY PART OF THE BODY<br />
  18. 18. CONTRACTIONS<br />
  19. 19. CONTRACTIONS<br />ISOMETRIC CONTRACTIONS<br />TENSION BUILDS TO THE MUSCLE’S<br />CAPACITY, BUT THE MUSCLE<br />NEITHER SHORTENS OR LENGTHENS. <br />USED IN<br />STANDING<br />SITTING<br />
  20. 20. CONTRACTIONS<br />
  21. 21. MUSCLE TWITCH<br />A single rapid contraction in response of muscle to a stimulus<br />Muscle fiber contracts and then relaxes <br />Strong twitch<br />Weak Twitch<br />Depends on the number of motor units activated<br />
  22. 22. MUSCLE CONTRACTION<br />THERE ARE THREE PHASES:<br />LATENT PERIOD<br />PERIOD OF CONTRACTION<br />PERIOD OF RELAXATION<br />
  23. 23. LATENT PERIOD<br />First few seconds following stimulation<br />Increase in muscle tension<br />Ca release<br />Cross bridge<br />No shortening of muscles <br />
  24. 24. PERIOD OF CONTRACTION<br />Cross bridges are active<br />Sarcomere shorten<br />
  25. 25. PERIOD OF RELAXATION<br />Re entry of Ca to Sarcoplasmic Reticulum<br />Muscle tension decreases to zero<br />Cross bridge ends<br />Muscle returns to original length<br />
  26. 26. GRADED MUSCLE RESPONSES<br />Variations in the degree of muscle contraction<br />Three ways muscle contraction are graded<br />Degree of muscle stretch<br />By changing the strength of the stimulus<br />By changing the frequency (speed) of stimulation<br />Summation<br />Tetanus<br />
  27. 27. Degree of muscle stretch (The Effect of Sarcomere Length on Tension)<br />Amount of tension (force) generated by the muscle depends on length of muscle before it was stimulated<br />Unstretched (Overly contracted , results weak contraction) <br />Overlapping of thin filaments<br />Overstretched (Too stretched, weak contraction results) <br />Thin filaments are pulled to the end of thick filaments<br />Moderately stretched (Optimum resting length produces greatest force when muscle contracts <br />Moderate overlapping produces maximum contraction developed when optimum overlap of thick and thin filaments<br />
  28. 28. Degree of muscle stretch (The Effect of Sarcomere Length on Tension)<br />
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