skeletal muscle proteins

1. Skeletal muscle proteins
Sarco-tubular system
E-C Coupling
Dr Pranith Kumar
Assistant professor
Physiology
Sapthagiri Medical College

2. Skeletal muscle Structure
• Muscle fibers
• Myofibrils
• Individual filaments – made up of contractile proteins
- Actin
- Myosin
- Tropomyosin
- Troponin
• Sarcoplasm , Sarcoplasmic reticulum

3. Structure
of skeletal
muscle

4. Light
microscopic
appearance

5. Electron
microscopic
appearance

6. Sarcotubular
system

7. Sarcotubular
system

8. Thick and Thin filaments

9. Configuration
Change

10. Sequence of events in excitation-contraction
coupling
Steps in contraction
• Motor nerve – propagated action potential
• Release of A Ch in synaptic cleft , binds to nicotinic receptors
• Depolarization of muscle membrane by increasing permeabilty to Na
• Generation of AP in muscle
• Spread of AP inward along T tubules
• Terminal cistern is depolarised, Ca released into myofibrils
• Increase in conc. of Ca++ by 2000 times
• Ca binds Troponin
• Confirmational change in Tropomyosin
• Myosin can now bind Actin – Sliding – Contraction

11. Sequence of events in excitation-contraction
coupling
Steps in relaxation
- Ca pumped back by Ca- Mg ATP ase
- Ca conc. ceases, Actin Myosin interaction terminates

12. THANK YOU