19 Physiology of Contraction – Stimulation of Muscle Nerve impulse reaches motor end plateNeuron releases AChElectrical charge travels along sarcolemmaElectrical charge travels down T tubulesElectrical charge travels to S.R.S.R. releases calcium into sarcoplasm
20 Physiology of Contraction – Activation of Myosin Calcium binds to troponinCross bridges formCalcium acts as an enzymeBreaks down ATP to ADP + PMyosin cross bridges moveSarcomere shortensMuscle shortens
21 Physiology of Contraction – Relaxation of Muscle Nerve impulse endsACh is broken down by acetylcholinesteraseCalcium is actively transported back into S.R.ADP + P = ATPBinds to cross bridgesMyosin cross bridges separate from actinBinding sites on actin are coveredThin myofilaments slip back to resting positionSarcomeres return to resting lengthMuscle fiber returns to resting length
26 How Skeletal Muscles Produce Movement Exert force on tendonsAttached to articulating bones forming a jointWhen muscle contracts, one bone moves toward the otherAttachmentsOrigin = attachment to stationary boneInsertion = attachment to moveable boneBelly = fleshy portion of muscle between tendons
27 Arrangement of Fasciculi ParallelConvergentPennateUnipennateBipennateMultipennateCircularArrangement is correlated with the power and range of movement of a muscle.
29 Group Actions Agonist or prime mover Antagonist Causes desired action Effect is opposite to agonistSynergist or fixatorAssists agonist
30 Lever Systems Bones = levers, joints = fulcrums Levers are acted upon by resistance, effortTypes1st class lever - fulcrum is placed between effort and resistance2nd class lever - fulcrum is at one end, effort is at the opposite end, resistance is in between3rd class lever - fulcrum is at one end, resistance is at the opposite end, effort is in betweenLeverage is responsible for a muscle’s strength and range of movement