1. MUSCLE CONTRACTION

2. Microscopic Anatomy of Skeletal Muscle Sarcomere Contractile unit of a muscle fiber Figure 6.3b

3. Microscopic Anatomy of Skeletal Muscle Sarcomere Thick filaments = myosin Thin filaments = actin Figure 6.3c

4. The Sliding Filament Theory of Muscle Contraction (5 Steps) 1) Sarcoplasmic reticulum releases Ca2+ Figure 6.7

5. The Sliding Filament Theory of Muscle Contraction (5 Steps) 2) Ca2+ causes myosin (thick) heads to attach to actin (thin) Figure 6.7

6. The Sliding Filament Theory of Muscle Contraction (5 Steps) 2) Ca2+ causes myosin (thick) heads to attach to actin (thin) Figure 6.7

7. The Sliding Filament Theory of Muscle Contraction (5 Steps) 3) ATP gives myosin power to “pull” actin along it Figure 6.7

8. The Sliding Filament Theory of Muscle Contraction (5 Steps) 3) ATP gives myosin power to “pull” actin along it Figure 6.7

9. The Sliding Filament Theory of Muscle Contraction (5 Steps) 4) Myosin heads bind to the next site along actin (thin) Figure 6.7

10. The Sliding Filament Theory of Muscle Contraction (5 Steps) 4) Myosin heads bind to the next site along actin (thin) Figure 6.7

11. The Sliding Filament Theory of Muscle Contraction (5 Steps) 5) Continued action causes actin to continue to slide along myosin Figure 6.7

12. The Sliding Filament Theory of Muscle Contraction (5 Steps) 5) Continued action causes actin to continue to slide along myosin Figure 6.7

13. Muscle Video http://www.youtube.com/watch?v=NRzJjx3ANuE 0-1:00