The Muscular System

1. The Muscular System

2. Muscle Function • produce movement • maintain posture • stabilize joints • generate heat

3. Functional Characteristics • Excitability- respond to a stimulus • Contractility- ability to shorten forcibly when adequately stimulated • Extensibility- the ability to be stretched • Elasticity- the ability of a muscle fiber to resume its resting length after being stretched

4. Skeletal Muscle • Striated • Multinucleate • Voluntary

5. Cardiac Muscle • Striated • Uninucleate • Involuntary • Branching • Intercalated discs

6. Cardiac Muscle Tissue

7. Smooth Muscle • Unstriated • Uninucleate • Involuntary • Hollow walled organs and blood vessels

8. Smooth Muscle Tissue

9. Gross Anatomy Skeletal Muscle

10. Gross Anatomy Skeletal Muscle

11. Muscle Anatomy myofibril muscle fiber (cell) sarcomere

12. Muscle Cell Sarcoplasmic reticulum

13. Myofibril

14. Myosin (Thick) Filament

15. Actin (Thin) Filament

16. Cross Bridges

17. Sliding Filament Hypothesis

18. actin troponin No Calcium Ion tropomyosin Calcium Ion Present myosin binding sites

19. Actin & Myosin Interaction

20. motor neurons neuromuscular junctions muscle fibers muscle bundle Biology 100 Human Biology Motor Unit spinal cord

21. Neuromuscular junctions muscle fibers branching axon to motor unit

22. Stimulation of Skeletal Muscle

23. Muscle Twitch period of relaxation period of contraction latent period stimulus

24. Contraction Response

25. Origin- fixed point of attachment; for biceps brachii O= clavicle and humerus Insertion- moveable, usually crosses a joint; O= radius Prime mover- - muscle group responsible for producing particular movement Antagonist- works opposite of prime mover Synergist-reduces undesirable or unnecessary movement Contraction of a muscle crossing 2 or more joints would cause movement of all if synergists weren’t there to stabilize it Ex. make a fist without bending wrist Fixator- specialized synergist- helps maintain posture; ex. muscles of the back fix scapula

26. Antagonistic Muscles

27. Naming skeletal muscles: • Direction of muscle fibers- straight, transverse • Size of muscles- maximus, minimus, longus, brevis • Location- frontalis, temporalis, occipitalis • # of origins- biceps, triceps, quadriceps • location of muscles origin and insertion- sternoclediomastoid- O= sternum and clavicle, I = mastoid process of temporal bone • shape of muscle- deltoid- triangle shape, trapezius- trapezoid shape • action of muscle- adductor muscle (adducts, brings in thigh)

28. aponerosa Frontalis Orbicularis oculi temporalis zygomaticus Masseter Orbicularis oris sternocledeomastoid

29. Frontal Obicularis oculi Temporalis Obicularis oris Masseter Sternoclediomastoid Deltoid Pectoralis major Biceps External oblique Rectus abdominus sartorius quadriceps Tibialis anterior

30. aponerosa occipitalis Trapezius Deltoid triceps Lattisimus dorsi Gluteus maximus hamstrings gastrocnemus Achilles tendon

31. Energy for muscle contraction: ATP is the only energy source ATP(ATPase + H2O) ADP + Pi • ATP is Generated by: • creatine phosphate • ADP + creatine phosphatecreatine + ATP • 2. lactic acid fermentation • From stored glycogen via anaerobic glycolysis; • glucosepyruvic acid (no O2) lactic acid • O2 • 3. aerobic respiration • Glucose  pyruvate  acetylCoA KrebsCO2 + H2O + ATP

32. Slow-Twitch Versus Fast-TwitchMuscle Fibers

33. Muscle Fiber Types • Fast glycolitic • Slow oxidative • Fast oxidative-glycolytic • Ratio- red:white (all 3 types in body)

34. Fast glycolitic: • white muscle fibers • low myoglobin • anaerobic glycolysis • few mitochondria • fast twitch fibers • high glycogen stores • short bursts • fatigues easily

35. Slow oxidative: • red muscle • aerobic • high myoglobin • low glycogen stores • lots mitochondria • slow • long distance

36. Fast glycolitic-oxidative: • red  pink • aerobic • fast • high myoglobin • intermediate amt. of mitochondria • intermediate glycogen • intermediate fatigue resistance

37. Red vs White Muscle • long distance blue fin tuna- mostly red meat • quick bursts- yellow tail- more white meat

38. Long distance Runner- aerobic respiration Sprinter- anaerobic respiration

39. Effects of Exercise • Disuse- atrophy • Muscles must be physically active if they are to remain healthy • Cast- muscle strength can decrease at a rate of 5%/ day; can use e- stimulus • Avoid muscle injuries: • warm up muscles- walk fast 5 minutes • then stretch- avoids pulls and tares

40. Muscle Injuries • cramp- sustained spasm or tetanic contraction; may be due to low blood sugar levels, electrolyte depletion, dehydration • strain- muscle pull • spasm- tics • hernia- protrusion of organ through body cavity wall may be due to heavy wts.

41. Isotonic and Isometric Contractions • Isotonic contraction • Contraction with a change in length • The muscle shortens and movement occurs. • Isometric contraction • Contraction without any change in length • The muscle does not shorten and there is no movement produced even though the muscle contracts.

42. Isotonic and Isometric Contractions Isometric Isotonic