Muscle Contraction: Filament Theory, Energy, Fatigue, Slides of Biology

Download Muscle Contraction: Filament Theory, Energy, Fatigue and more Slides Biology in PDF only on Docsity! Sliding Filament Theory Dr. R. Venkatesan M.Sc (Ex.Phy)., M.Sc (Psy)., M.P.Ed., M.Phil.,PGDY., Ph.D. Contraction Sequence: Sliding Filament Theory Figure 12-9 (steps 1 & 2): The molecular basis of contraction Skeletal Muscle Contraction: Mechanism (a) Muscle fiber T-tubule receptor Axon terminal of somatic motor neuron Sarcoplasmic reticulum Tropomyosin Troponin Myosin thick filament Somatic motor neuron releases ACh at neuro- muscular junction. Net entry of Na* through ACh receptor- channel initiates a muscle action potential.  Skeletal Muscle Contraction: Mechanism Myosin thick filament M line Distance actin moves te Action potential in t-tubule alters conformation of DHP receptor. DHP receptor opens Ca** release channels in sarcoplasmic reticulum and Ca** enters cytoplasm. Ca** binds to troponin, allowing strong actin- myosin binding Myosin heads execute power stroke. Actin filament slides toward center of sarcomere Energy for Contraction: ATP & Phosphocreatine • Aerobic Respiration – Oxygen – Glucose – Fatty acids – 30-32 ATPs • Anaerobic Respiration – Fast but – 2 ATP/glucose • Phosphocreatine ATPs • Rate – 2-3 times faster – SR uptake of Ca2+ – ATP splitting • Anaerobic/Fatigue easily – Power lifting – Fast/delicate – Sprint Fiber Contraction Speed: Fast Twitch Fiber Contraction Speed: Fast Twitch Figure 12-15: Fast-twitch glycolytic and slow-twitch muscle fibers • Oxidative Fast Twitch – Intermediate speed – Anaerobic & aerobic • Slow Twitch: Aerobic, less fatigue – More mitochondria – More capillaries – Myoglobin – Endurance activities – Postural muscles Fiber Contraction Speed: Oxidative Fast & Slow