1. The Muscular System

2. or “Everything you ever wanted to know about Muscles, but were afraid to ask” !!!

3. Did you know that ? -more than 50% of body weight is muscle ! -And muscle is made up of proteins and water

5. The Muscular System Function: movement 3 types of muscle –Skeletal –Cardiac –Smooth

6. Info About Muscles Only tissue able to contract create movement by flexing and extending joints –Flex = bring toward body –Extend = bring away Energy converters (many muscle cells contain many mitochondria)

7. Drawings of 3 Types of Muscles

8. Classification of Muscle SkeletalCardiacSmooth Big Drawing description of appearance location # of nuclei method of control

9. Three types of muscle SkeletalCardiacSmooth

10. Classification of Muscle Skeletal- found attached to bones Cardiac- found in heart Smooth- Found in internal organs Striated, multi- nucleated Striated, 1 nucleus Not striated, 1 nucleus voluntaryinvoluntary

11. Characteristics of Muscle Muscle cell = muscle fiber (why?) Contraction due to movement of microfilaments (protein fibers) All muscles share some prefixes: * myo- and mys- refer to “muscle” * sarco- refers to “flesh”

12. Shapes of Muscles Triangular- shoulder, neck Spindle- arms, legs Flat- diaphragm, forehead Circular- mouth, anus

13. Skeletal Muscle Most are attached by tendons to bones Cells have more than one nucleus (multinucleated) Striated- have stripes, banding Voluntary- subject to conscious control Tendons are mostly made of collagen fibers Found in the limbs Produce movement, maintain posture, generate heat, stabilize joints

14. Structure of skeletal muscle Each cell (fibre) is long and cylindrical Muscle fibres are multi-nucleated Typically 50-60mm in diameter, and up to 10cm long The contractile elements of skeletal muscle cells are myofibrils

15. Skeletal muscle - Summary Voluntary movement of skeletal parts Spans joints and attached to skeleton Multi-nucleated, striated, cylindrical fibres

16. Smooth Muscle No striations Spindle shaped Single nucleus Involuntary- no conscious control Found mainly in the walls of hollow organs

17. Smooth muscle Lines walls of viscera Found in longitudinal or circular arrangement Alternate contraction of circular & longitudinal muscle in the intestine leads to peristalsis

18. Structure of smooth muscle Spindle shaped uni-nucleated cells Striations not observed Actin and myosin filaments are present( protein fibers)

19. Smooth muscle - Summary Found in walls of hollow internal organs Involuntary movement of internal organs Elongated, spindle shaped fibre with single nucleus

20. Cardiac Muscle Striations Branching cells Involuntary Found only in the heart Usually has a single nucleus, but can have more than one

21. Cardiac muscle Main muscle of heart Pumping mass of heart Critical in humans Heart muscle cells behave as one unit Heart always contracts to it’s full extent

22. Structure of cardiac muscle Cardiac muscle cells (fibres) are short, branched and interconnected Cells are striated & usually have 1 nucleus Adjacent cardiac cells are joined via electrical synapses (gap junctions) These gap junctions appear as dark lines and are called intercalated discs

23. Cardiac muscle - Summary Found in the heart Involuntary rhythmic contraction Branched, striated fibre with single nucleus and intercalated discs

24. Muscle Control Type of muscle Nervous control Type of control Example Skeletal Controlled by CNS Voluntary Lifting a glass Cardiac Regulated by ANS Involuntary Heart beating Smooth Controlled by ANS Involuntary Peristalsis

25. Types of Responses Twitch- –A single brief contraction –Not a normal muscle function Tetanus –One contraction immediately followed by another –Muscle never completely returns to a relaxed state –Effects are compounded

26. Where Does the Energy Come From? Energy is stored in muscles in form of ATP ATP comes from breakdown of glucose during Cell Respiration Occurs in Mitochondria of cell When a muscle is fatigued (tired) it is unable to contract because of lack of Oxygen Lactic Acid is produced when lack of O 2, causing muscle soreness

27. Exercise and Muscles Isotonic- muscles shorten and movement occurs ( most normal exercise) Isometric- tension in muscles increases, no movement occurs (pushing one hand against the other)

28. How are Muscles Attached to Bone? Origin = fixed attachment to immovable bone Insertion = attachment to movable bone; moves with contraction Muscles are always attached to at least 2 points Movement is attained due to a muscle moving an attached bone Bones act as levers

29. Muscles work in pairs. They can only PULL, they can’t push.

30. Muscle pair example

31. What are 3 other antagonistic pairs & their actions?

32. Muscle Attachments Origin Insertion

33. Flexion Types of Musculo-Skeletal Movement

34. Extension

35. Hyperextension

36. Abduction, Adduction & Circumduction

37. Rotation

38. More Types of Movement…… Inversion- turn sole of foot medially Eversion- turn sole of foot laterally Pronation- palm facing down Supination- palm facing up Opposition- thumb touches tips of fingers on the same hand

39. The Skeletal Muscles There are about 650 muscles in the human body. They enable us to move, maintain posture and generate heat. In this section we will only study a sample of the major muscles.

40. Sternocleidomastoideus Flexes and Rotates Head

41. Masseter Elevate Mandible

42. Temporalis Elevate & Retract Mandible

43. Trapezius Extend Head, Adduct, Elevate or Depress Scapula

44. Latissimus Dorsi Extend, Adduct & Rotate Arm Medially

45. Deltoid Abduct, Flex & Extend Arm

46. Pectoralis Major Flexes, adducts & rotates arm medially

47. Biceps Brachii Flexes Elbow Joint

48. Triceps Brachii Extend Elbow Joint

49. Rectus Abdominus Flexes Abdomen

50. External Oblique Compress Abdomen

51. External Intercostals Elevate ribs

52. Internal Intercostals Depress ribs

53. Diaphragm Inspiration

54. Forearm Muscles Flexor carpi—Flexes wrist Extensor carpi—Extends wrist Flexor digitorum—Flexes fingers Extensor digitorum—Extends fingers Pronator—Pronates Supinator—Supinates

55. Gluteus Maximus Extends & Rotates Thigh Laterally

56. Rectus Femoris Flexes Thigh, Extends Lower Leg

57. Gracilis Adducts and Flexes Thigh

58. Sartorius Flexes Thigh, & Rotates Thigh Laterally

59. Biceps Femoris Extends Thigh & Flexes Lower Leg

60. Gastrocnemius Plantar Flexes Foot & Flex Lower Leg

61. Tibialis Anterior Dorsiflexes and Inverts Foot