Acetylcholine diffuses across the synaptic cleft and binds to the nicotinic acetylcholine receptors that dot the motor end plate.
This influx of Ca2+ triggers excitation-contraction coupling, a biochemical cascade that causes neurotransmitter-containing vesicles to fuse to the motor neuron's cell membrane and release acetylcholine into the synaptic cleft. Mitochondrionġ5 Mechanism of action Upon the arrival of an action potential at the axon terminal, voltage-dependent calcium channels open and Ca2+ ions flow from the extracellular fluid into the motor neuron's cytosol. Presynaptic terminal 2ĭetailed view of a neuromuscular junction: 1. Myofibrilġ4 Detailed view of a neuromuscular junction: 1. Global view of a neuromuscular junction: 1. Synapse between neuron & effector Cholinergic (ACh) nicotinic receptors Motor end-plate postsynaptic membrane folds packed with receptors increased surface area ~ġ3 Global view of a neuromuscular junction: 1. Pale red properties intermediate to types 1 & 2b rapid, brief contraction slow to fatigue produce least force Aerobic & Anaerobic metabolism many capillaries & mitochondria ~ White fibers rapid, brief contraction fast to fatigue produce about 10x force of Type 1 Anaerobic metabolism fewer capillaries & mitochondria ATP generated by glycolysis lactic acid buildup ~ĩ Type 2a Fibers Fast fatigue-resistant fibers Fast-twitch glycolitic fibers (putih) Fast-twitch oxidative fibers (merah) Slow twitch oxidative fibers (merah) Setiap orang punya 3 tipe otot, tapi berbeda pada komposisi dominan (Jauhari Johan vs John Murray/ Ben Johnson)ħ Type 1 Fibers Slow fibers Aerobic metabolismĭark red slow, sustained contraction slow to fatigue Aerobic metabolism many capillaries & mitochondria oxygen required for ATP synthesis myoglobin gives dark red appearance ~Ĩ Type 2b Fibers Fast fatigable fibers Anaerobic metabolism distal, bersifat mobilĦ TIPE OTOT SKELETAL Berdasarkan kecepatan kontraksi dan daya tahan terhadap fatigue. proksimal, bersifat stasioner Insersio : perlekatan pada bag. Melekat ke tulang melalui tendo Origo : perlekatan pada bag. Striate muscle Force for limb movements flexion - closes joint extension - opens joint Contract or relax ~Ĥ OTOT SKELETAL 40% BB tubuh Fungsi : mengatur posisi dan gerak rangka
2 TIPE OTOT Otot Skeletal (lurik/striata) Otot Jantung (lurik/striata)
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