lec_18_slides - Isolated cardiac myocyte in culture...

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undergoing periodic contractions Structure of muscle Courtesy of Jan Lammerding. Used with permission. Isolated cardiac myocyte in culture 1 Image removed due to copyright considerations.
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Skeletal (striated) and smooth muscle Temporal patterns of muscle contraction max ) l (b) Smooth muscle (a) Skeletal muscle Single twitch Periodic sequence of excitations Fused tetanus (F 2
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Tension-length curves for a muscle fiber (relaxed and maximally stimulated) l Empirically determined force-velocity relationship obtained Hill’s equation from macroscopic measurements v v max = 1 - F F max ( ) 1 + max ( ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.2 0.4 0.6 0.8 1 v/vmax F/Fmax or P/Pmax vF v max F max = 1 - ( F max F ( ) + C C F F F/F max vF/F max v max F F max ) 3
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Source of energy for muscle Hydrolysis of adenosine triphosphate (ATP) creating adenosine diphosphate (ADP): æ ATP æ Æ ææ ADP + P i actomy sin ATPase Ê [ ATP ] ˆ D G = D G 0 - kT ln Á ˜ P i Ë [ ADP ][ ] ¯ or approximately -25 kT ( displacement ~ 5 nm) Power/weight ~ same as an automobile engine 4
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A rise in cytosolic Ca 2+ triggers muscle contraction (part I) 2+ Step 1 : An excitation signal travels along the efferent nervous pathways towards the muscle. Step 2 : The excitation signal de-polarizes the cell membrane. This allows spread of the action potential along the Step 3: The potential triggers the release of calcium into the unit.
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  • Spring '03
  • RogerD.Kamm
  • Adenosine triphosphate, myosin head

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