1. The Muscle System

2. Muscles Found in every organ of body Three types Skeletal Cardiac Smooth

3. Function of Muscles Movement Tension Heat generation

4. Muscle Anatomy

5. Anatomy of A Muscle

6. Single Muscle FiberFascicle Muscle

7. Muscle Fiber

8. Elongated Multinuleated Myofibrils running entire length SR surrounds each myofibril Mitochondria embedded throughout

9. Sarcomere The contractile unit

10. Anatomy of a MuscleMuscle Fascicle Single Muscle Fiber Muscle Fascicle Muscle Cell

11. Muscle Movement

12. Muscle Contraction All muscles work the same way –Contract and relax –All muscles are excitable: Nerves stimulate Muscle contracts

13. Mechanism of Nerve Stimulation 1. Nerve impulse reaches terminal 2. ACh released 3. ACh diffuses across cleft 4. ACh attaches to receptors 5. Sarcolemma becomes permeable to Na+ 6. Action Potential (charge) travels down cell

14. 1. Calcium released from SR, triggering exposure of binding sites on actin 2. Myosin binds with actin 3. The power stroke: Actin filaments pulled - slide past myosin 4. ATP binds to cross bridge, disconnects from actin 5. ATP re-energizes cross bridge 6. Calcium ions go back to SR Mechanism of Muscle Contraction

15. Muscle Metabolism

16. ATP used to: –Energize myosin cross bridge –Disconnect myosin cross bridge from actin –Energize calcium pump

17. ATP: The Energy Source Adenine P P P Adenine P + Energy

18. Muscle cells use stored ATP Within seconds, stored ATP is used up The First Seconds of Contraction

19. 20-ish Seconds of Contraction creatine phosphatecreatine ATP

20. 40-ish Seconds of Intense Contraction pyruvic acid glycogen glucose 2 ATP lactic acid Anaerobic metabolism

21. Long Term Muscle Activity Aerobic metabolism glycogen glucose 36 ATP CO 2 + H 2 0

22. Muscle Metabolism Stored ATP Creatine Phosphate 1 ATP Anaerobic Metabolism Stored Glycogen 2 ATP Aerobic Metabolism Glucose/glycogen 36 ATP

23. Contraction Strength and Control

24. Motor Units A neuron and all the cells it stimulates All cells of motor unit contract together Size of motor unit determines precision

25. Recruitment Muscle recruitment: more motor units are activiated

26. Summation Summation: Rate of muscle stimulation is increased

27. White or Dark Muscle: Slow or Fast Twitch

28. Fast Twitch: White Muscle Rapid, powerful response Depend on anaerobic pathways Packed with actin and myosin Muscles fatigue rapidly

29. Slow Twitch: Red Muscle Contract slowly, but with great endurance Depend on aerobic pathways Packed with mitochondria, myoglobin

30. Strength training –Builds more fast-twitch myofibrils Aerobic training –Builds endurance –Increases blood supply to muscle cell Exercise and Training

31. Anabolic – induces muscle growth Mimic testosterone Stimulates protein formation in muscle cells May cause: –Increase in muscle strength without increase in tendon strength –Liver/heart disease –Sterility Anabolic Steroids

32. Androgenic Steroids Androgenic steroids – male/female hormones Andro – testosterone precursor

33. Side Effects of Steroids

34. Side Effects of Steroids

35. Facial Hair in Women

36. Gynecomastia

37. Diseases and Disorders

38. Muscular dystrophy Tetanus Muscle cramps Sprains/Strains Diseases and Disorders of the Muscular System

39. Muscular Dystrophy

40. Tetanus

41. Muscle Cramps

42. Sprains/Strains

43. Strength versus Size

44. Moving Bones

45. Skeletal Muscle Moves Bones More than 600 skeletal muscles Origin: attachment to stationary bone Insertion: attachment to moving bone origin insertion origin

46. Antagonistic Pairs Antagonistic muscles oppose each other