1. Muscle Contraction Prof. Vajira Weerasinghe Dept of Physiology Faculty of Medicine University of Peradeniya

4. Skeletal Muscle Fiber Structure Figure 12-3b: ANATOMY SUMMARY: Skeletal Muscle Pg. 401

5. Muscle Fiber Structure Figure 12-4: T-tubules and the sarcoplasmic reticulum Pg. 402

10. Ca++ Ca++

13. THIN FILAMENT (Actin) THICK FILAMENT (Myosin)

14. THIN FILAMENT THICK FILAMENT Troponin Actin Myosin Tropomyosin

17. Detachment Sliding Binding Ca 2+ Troponin Actin Myosin Tropomyosin Ca 2+ Myosin binding sites Ca 2+ Ca 2+

19. Ca ++ Troponin Actin Myosin ATP Ca ++ binds to troponin Tropomyosin exposes actin myosin head binds to actin & cross bridge forms Filaments slide ATP is broken down New ATP comes, Ca is removed, ready to detach

25. Timing of Electrical & Mechanical Events Myogram of Single Muscle Twitch

29. Muscle twitch

32. Summation and tetanus

37. Staircase phenomenon (treppe)

38. Staircase effect, summation and tetanus

39. Tetanus

41. Isotonic contraction

43. Isometric contraction