KINESIOL 1Y03 Muscle Physiology PDF

KINESIOL 1Y03 Neuromuscular Junction ATP Requirements neuromuscular junction: NMJ; connection sodium potassium ATPase: sarcolemma; 31: Muscle Physiology...

KINESIOL 1Y03 Neuromuscular Junction ATP Requirements neuromuscular junction: NMJ; connection sodium potassium ATPase: sarcolemma; 31: Muscle Physiology between nervous system and muscle re-establish RMP axon collateral of somatic motor neuron: myosin ATPase: myosin heads; detach and Sliding Filament Theory branch of somatic motor neuron; created at store energy for power strokes sliding filament mechanism: how actin perimysium level; 1 axon collateral per 1 sarcoendoplasmic reticulum calcium muscle fiber ATPase: allows relaxation and myosin move relative to each other to synaptic end bulbs: collateral branches into shorten the muscle; amount of overlap bulbs in one small region (NMJ) changes (H-zone and I-band), but actual acetylcholine: always the NT contained in myofilament lengths do not change (A- synaptic vesicles; always causes EPSP if band) AP reaches threshold asynchronized: not all heads attach at the motor end plate: region of sarcolemma same time, so that when one lets go there associated with synaptic end bulb; has are still others holding in place acetylcholine ligand gated ion channels maximal contraction: actin overlaps; H- pathway: AP > opens voltage gated Ca zone and I-band have disappeared; length channel > Ca rushes into cell > vesicles of sarcomere is close to length of A-band release ACh into cleft > ACh binds to (also includes Z-disc) ligand gated channels on sarcolemma > depolarization > nearby voltage gated Cross Bridge Cycle channels create MAP cross bridge cycle: also contraction cycle; differences from neurons: ligand and voltage process of myosin binding onto actin and gated channels are located near each other, moving it towards the M-line creating MAP right beside NMJ, generally right cross bridge: binding of myosin head onto in the middle of the muscle fiber; MAP moves actin active site in different directions (away from NMJ) preparation: myosin heads are activated in acetylcholinesterase: on postsynaptic the relaxed condition; have stored energy membrane; rapidly breaks down ACh into and are in upright position choline and acetic acid; choline is taken up into presynaptic terminal and repackaged, myosin ATPase: hydrolyzes ATP > ADP + P; acetic acid is taken up by neighboring cells products bind onto myosin heads motor unit: a group of muscle cells stimulated step 1: active sites are exposed by a single motor neuron; there can be many SR: releases Ca+ motor units in a muscle Ca+: binds to troponin troponin: changes shape, moves tropomyosin Excitation Contraction off of active sites excitation-contraction coupling: step 2: myosin binds onto active sites transformation of MAP into muscle phosphate: released during binding contraction ADP: stays bound to head resting state: Ca channels are closed (Ca cross bridge: formed stored in SR), troponin in resting state step 3: power stroke pulls actin (tropomyosin covers active sites) energy: comes from myosin heads (which contraction: AP > MAP > sarcolemma > T- move towards the M-line) ADP: released during bending tubule > membrane potential change > Ca channels open > Ca enters sarcoplasm > step 4: myosin head releases actin Ca binds to troponin > troponin shape ATP: required for this process; binds onto shifts > tropomyosin exposes binding sites head, causing release of actin rigor mortis: stiffness in dead people; muscles > actin and myosin form X-bridge mass released Ca, so heads bind, but there is power stroke: continues until Ca is taken no ATP production, so the heads never release back up into SR step 5: ATPase hydrolyzes ATP SERCA pump: sarcoendoplasmic reticulum calcium ATPase; responsible for Ca take-up myosin head: re-energized by new ADP and P ATP: required for relaxation of muscle Electrical Properties resting membrane potential: ~-85 mV potassium leak channels: more numerous than in neurons sodium potassium pump: requires ATP; high [K+] inside, high [Na+] outside muscle action potential: produced after Na rushes into cell; voltage gated K and Na channels open on the sarcolemma summary sheet by Jasmine Ah Yong for KINESIOL 1Y03 (2022)