Esdin LS 2 Lec 5 Muscles

Pi which brings the myosin head to the energized

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Unformatted text preview: the myosin head •  Power stroke occurs 18 4/21/13 Cross Bridge Cycle •  ADP unbinds •  ATP binds to myosin head on its binding site, causing detachment to occur •  ATP is hydrolyzed to ADP & Pi which brings the myosin head to the energized state again What Stops the Cycle? •  Two major steps must happen to stop the cross bridge cycle from occurring –  Removing acetylcholine –  Removing calcium 19 4/21/13 What Stops the Cycle? to end contraction, pump calcium back to the SR (active transport), remove ACh •  Acetylcholine esterase breaks down acetylcholine •  Ca2+ is pumped back to SR How Can ACh Be Removed? Axon terminal Ca2+ Neurotransmitter (ACh) Sarcolemma N a+ Ach esterase Muscle cell ACh receptor 20 4/21/13 Where Does the Muscle Get the Energy From? •  Muscle get glucose and oxygen to produce energy •  There are three sources of energy –  Creatine phosphate –  Cellular respiration –  Glycolysis followed by fermentation Phosphogens Creatine phosphate Arginine phosphate 21 4/21/13 What Causes Muscle Fatigue? •  Local increase of inorganic phosphate •  Build up of acid •  Depletion of energy tetanus, muscles exposed to clostridium tetani (releases toxins) muscles work more, jaw locks, muscles keep firing wrinkles (overexcitations of motor neurons on the facial muscles so wrinkles appear) botox shot of clos. bot. inhibits release of NT and messes with Ca channels nerve gas: block the ability to degrade the signal, lots of ACh, hyper excitation of muscle 22...
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