Muscles

1. Muscles • Skeletal muscles  review (see also H.P.) • Smooth muscles • Cardiac muscles

2. MUSCLES - Review

3. Skeletal Muscles • General information • Muscle fiber structure • Muscle contraction: • the sarcomere • Contraction • Sources of energy • Twitch • Smooth muscle

4. Muscles • General information • Muscle fiber structure • Smooth muscle • Muscle contraction: • the sarcomere • Contraction • Sources of energy • Twitch

5. Table 12-1

6. Muscles • General information • Muscle fiber structure • Muscle contraction: • the sarcomere • Contraction • Sources of energy • Twitch

7. Figure 12-3a - Overview

8. Figure 12-3b

9. Figure 12-3c

10. Figure 12-3d

11. Figure 12-3e

12. Figure 12-3f

13. Figure 12-4

14. Figure 12-6

15. Muscles • General information • Muscle fiber structure • Muscle contraction: • the sarcomere • Contraction • Sources of energy • Twitch

16. Figure 12-7

17. Figure 12-8

18. Muscles • General information • Muscle fiber structure • Muscle contraction: • the sarcomere • Contraction • Sources of energy • Twitch

19. Figure 12-9 - Overview

20. Figure 12-10 - Overview

21. Figure 12-11 - Overview

22. Muscles • General information • Muscle fiber structure • Muscle contraction: • the sarcomere • Contraction • Sources of energy • Twitch

23. Figure 12-13

24. Sources of energy • Aerobic conditions (importance of myoglobin) - ATP - creatine phosphate - glucose – glycogen - Fatty-acids • Anaerobic conditions: • Only 2 ATP per glucose • lactic acid formation

25. Muscles • General information • Muscle fiber structure • Muscle contraction: • the sarcomere • Contraction • Sources of energy • Twitch

26. Figure 12-12

27. Figure 12-14

28. Figure 12-15

29. Table 12-2

30. Figure 12-16 - Overview

31. Figure 12-17 - Overview

32. Figure 12-18

33. Figure 12-19 - Overview

34. Figure 12-20 – Overview (1 of 3)

35. Figure 12-24

36. Smooth Muscles • General information • Muscle contraction

37. Figure 12-25 - Overview

38. Figure 12-25a

39. Figure 12-25b

40. Figure 12-26

41. Smooth Muscles • General information • Muscle contraction

42. General considerations • Many types of smooth muscles • Controlled by APs, paracrines and hormones • Variable electric properties • Contraction and relaxation influenced by many factors

43. Single unit smooth muscle = contract as one unit  digestive system Multi-unit smooth muscle = each fiber must be associated with an axon terminal varicosity  iris, uterus (not pregnant)

44. Contraction Figure 12-27 - Overview

45. The excitatory ion for AP is calcium, not sodium as in skeletal muscle The calcium binding protein is calmodulin, not troponin The binding of myosin and actin occurs through a pathway different from skeletal muscle (MLCK) Muscle stretch can trigger channel opening thus contraction Contraction Figure 12-28

46. Ca++ must be removed  pumped back in cisternae by an ATPase, expelled in ECF by ATPase pump and Ca/Na antiport Relaxation Figure 12-29

47. Smooth muscle contraction is not always linked to membrane depolarisation Figure 12-31 - Overview

48. Cardiac muscles • Contractile fibers: the ones that contract • Conducting fibers: the ones triggering the APs

49. Difference between skeletal and cardiac contractile muscle fiber: calcium channels open first during the repolarisation phase  plateau A single AP (especially repolarisation) lasts much longer than a skeletal muscle fiber AP The cardiac AP

50. Figure 14-14 - Overview