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This 2 page Class Notes was uploaded by Laury Kreiger on Friday September 18, 2015. The Class Notes belongs to ANS 3634C at University of Florida taught by Dwain Johnson in Fall. Since its upload, it has received 28 views. For similar materials see /class/206671/ans-3634c-university-of-florida in Animal Science at University of Florida.
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Date Created: 09/18/15
TWELVE STEPS TO MUSCLE CONTRACTION AND RELAXATION Muscle Contraction Electrical impulse arrives from the motor nerve at the motor end plate neuromuscular junction and spreads over the sarcolemma In resting muscle there is a electrical gradient across the sarcolemma such that the outside is more positive that the inside As the gradient changes a phenomenon occurs called depolarization When the sarcolemma undergoes depolarization the Ttubules communicate the electrical impulse almost simultaneously to all the sarcomeres of the muscle ber When the Ttubules become depolarized this change is transmitted to the membranes of the sarcoplasmic reticulum SR causing it to increase in permeability CaH ions escape from the SR which is the normal storage vessel in resting muscle CaH is immediately bound to a speci c binding site on actin thin lament which causes an uncovering of the myosin binding site in actin allowing the energized myosin head to attach The interaction between myosin and actin along with ATP form the force generating complex The myosin head undergoes a energyyielding conformational change so that the cross bridge changes its angular relationship to the aXis of the thick lament causing the thin lament to be moved along the thick lament known as a power stroke The myosin head reverts from its energized to its deenergized state ATP binds on the myosin head and causes the disassociation between myosin and actin Muscle Relaxation 11 When the electrical stimulation ceases the sarcolemma regains its original permeability pattern and returns to its original polarized state outside inside and the membrane of the SR returns to its original state 12 The Ca present in the sarcoplasm is now transported in an energy requiring process across the membrane into the SR so that the concentration of Ca in the sarcoplasm is brought to its low resting concentration Muscle Capillary Bed Fibers I Collagen Fibers Reticular Fibers Nucleus Sarcolemma Nufle I Myo bril Blood Vessels 539 quot 39 l if r gs lBand Endomyslum 39IS One A Band Myofilament Perimyslum arcomere 2 Lin Epimysium p e Collagen Fibers Sarcoplasm Sarcoplasmic Lateral Cistern 39 I ae Reheulumk Myofibrlls I T Tubule Triad arcoplasmlc Reticulum Z Line Lattice 1257 2 Line my5ium Actin Filament l B I R and G yc geny ltgasement Lamina My quot3 osln Filament A Band Granules Mitochondria Couagen Sa39 emma