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Muscle Anatomy and Physiology

Muscle Anatomy and Physiology. The Review!. Skeletal Muscle Functions. Locomotion Movement Maintaining Posture Generating Heat!. Characteristics. Excitability: Membrane potentials, action potentials, Na+ and K+ Contractility: Sarcomeres, Sliding Filament Theory, Ca++ and ATP

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Muscle Anatomy and Physiology

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  1. Muscle Anatomy and Physiology The Review!

  2. Skeletal Muscle Functions • Locomotion • Movement • Maintaining Posture • Generating Heat!

  3. Characteristics • Excitability: Membrane potentials, action potentials, Na+ and K+ • Contractility: Sarcomeres, Sliding Filament Theory, Ca++ and ATP • Extensibility • Elasticity

  4. Anatomy: Max Min • Muscle, fascicle, fiber, fibrils containing sarcomeres, filaments – actin and myosin • Fascia /epimysium, perimysium,endomysium • “Bundles within bundles”

  5. Contractile units:SARCOMERES • Thin: actin, troponin, tropomysim • Thick: myosin • Sarcomere Regions: Z-lines, A-band, I-band, H-Zone

  6. Sliding Filament Theory of Contraction • All-or-None • Sarcomere units shorten by thin and thick filaments “sliding” past each other • Requires Ca++ • Requires ATP

  7. Excitability! The stimulus to contract • Resting Membrane Potential: Membranes separate charges: polarized with positive Na+ outside • Depolarization: Charge reversal across membrane

  8. Depolarization reaches Threshold voltage and All-or-None Depolarization travels along membrane Action Potential AP travels along sarcolemmaT-tubulessarcoplasmic reticulumTerminal CisternaeCalcium released Troponin-Calcium move Tropomysin exposing myosin binding sites Why all the Excitement?

  9. Remember the Simulation? • Motor Nerve – Muscle Fiber • Pre-Synaptic Terminal: Acetylcholine released • Post-Synaptic Terminal: Ach binds to Ach receptors =>Muscle fiber depolarization • Contraction!

  10. The Neuromuscular Junction An Interesting Place to Chemically Manipulate Neuro- Muscular Function…Causing Paralysis or Worse…

  11. Motor Units = Motor Control • Motor Neuron + Muscle fiber(s): fine vs. strong • Twitch: Single contraction & relaxation • Recruitment: Smooth moves • Tetanus: Sustained contraction

  12. Energetics of Contraction • ATP-PC: fast, limited • Anaerobic Glycolysis: cytosolic breakdown of Glucose without O2 • Aerobic Oxidation: slow, but plentiful supply of ATP

  13. Final Exam: • 20 Multiple Choice • 2 Matching: Bundles of bundles, and movement terms • 5 Short Answers: • ATP systems • Roll of Calcium in Contraction • Sarcomere: Anatomy and Function • Poisons/Drugs affecting NMJ – Neurotransmitters • Your Burning Question/Answer

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