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TOTE THAT BARGE, LIFT THAT BALE Human muscles: physiology, use, disorders, and diseases Olli 2017 Janice Ott Mus = little mouse Sarco = flesh 40-50% body weight 600+ skeletal muscles Transform chemical energy (ATP) into mechanical energy Muscles can only pull, never push Functions: 1. Movement 2. Shape 3. Maintain posture 4. Heat 3 Main Types • Skeletal • Cardiac • Smooth Cardiac Muscle Smooth Muscle Skeletal Cardiac Smooth Control Voluntary Involuntary Involuntary Where Attached to bones Heart Intestines Blood vessels Action Fast. Must rest Rapid, steady pacemaker Slow. Stay contracted Oxygen Anaerobic short Aerobic Aerobic Morphology Striated Striated Smooth Characteristics: Excitability Contractibility Extensibility Elasticity Parts Origin (fixed) Insertion (movable bone) usually crosses a joint shortens muscle Belly Connective tissue endomysium perimysium epimysium tendons (connect muscle to bone) fascia (connect muscle to muscle) Blood vessels Motor units each muscle has at least one nerve Some 4 muscles/1 nerve (fine) Some 1000 muscles/1 nerve (gross) Muscle tone Constant nerve stimulation to maintain tone If no, become flaccid Micrsoscopic and action Huge, long cells Some 30 cm long A. Myofibril 1000s/cell full of myofilaments thick (myosin) thin (actin) B. Sarcoplasmic reticulum stores calcium ions C. T tubules D. Multiple nuclei E. Many mitochondria Let’s move a muscle Sliding filament theory 1. 2. 3. 4. 5. 6. 7. 8. Message from brain Neuro muscular junction Neurotransmitter released Ach attaches to receptors Message along sarcolemma Ca++ released from SR Binds with actin, exposes Binding site on myosin 9. Filaments pulled together 10. Energy (ATP) releases 11. Everything relaxes 12. Ca++ returns ATP Rigor Mortis Muscles stiffen 3-4 hrs. after death Peaks at 12 hours No oxygen, no ATP No calcium movement 48-60 hours degradation Curare Blocks Ach receptors Only local, not CNS Treated: rabies, tetanus, epilepsy, surgery Animals research 1870s antivivisection laws Daniele Bovet 1957 Nobel prize used succinylcholine for muscle relaxation Nerve gas Blocks acetylcholinesterase Saliva, tears, coughing Convulsion Urination, defecation Asphyxiation: respiratory Names Size: maximus, longus Shape: deltoid, trapezoid Location: pectoralis, brachia # of origins: biceps, triceps, quadriceps Action: extensor carpii Main movements: 1. Adduction 2. Abduction 3. Flexion 4. Extension 5. Rotation