1. PowerPoint Lecture Outlines to accompany
Hole’s Human
Anatomy and Physiology
Eleventh Edition
Shier w Butler w Lewis
Chapter 9
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Functions of Muscular System
Movement
Posture Maintenance
Joint Stability
Heat Generation

3. Three Types of Muscle Tissue
Skeletal Muscle
usually attached to bones
under conscious control
striated
Cardiac Muscle
wall of heart
not under conscious control
striated
Smooth Muscle
walls of most viscera, blood vessels, skin
not under conscious control
not striated

4. Structure of a Skeletal Muscle
Composed of:
skeletal muscle tissue
nervous tissue
blood
connective tissues
fascia
tendons
aponeuroses

5. Skeletal Muscle Structure
Muscle cells called muscle fibers wrapped in endomysium
Bundles of muscle fibers called fasicles wrapped in perimysium
Many fasicles make a muscle and are wrapped in epimysium

6. Skeletal Muscle Fiber Structure
Muscle fibers are long, thin cells made of myofibrils
Myofibrils composed of 2 types of cytoskeleton
Myosin – thick protein filaments
Actin – thin protein filaments

7. Skeletal Muscle Fibers
sarcolemma - cell membrane
sacroplasm – cell cytoplasm
sarcoplasmic reticulum – endoplasmic reticulum
transverse tubule - channel that is continuous with sarcolemma and extends into sarcoplasm

8. Sarcomere: Unit of contraction
I bands – light area = actin only
A bands – dark area = overlapping actin and myosin
Z lines – dividing line between individual sarcomeres

9. Special Features of Myofilaments
Thin Filaments = Actin
associated with troponin and tropomyosin
Thick Filaments = Myosin
cross-bridges

10. Neuromuscular Junction
Site where an axon and muscle fiber meet
motor neuron
motor end plate
synapse
synaptic cleft
synaptic vesicles
neurotransmitters

11. Motor Unit single motor neuron
all muscle fibers controlled by motor neuron
Sliding Filament Model video

12. Stimulus for Contraction
acetylcholine (ACh)
nerve impulse causes release of ACh from synaptic vesicles
ACh binds to ACh receptors on motor end plate
generates a muscle impulse

13. Excitation Contraction Coupling
muscle impulses cause sarcoplasmic reticulum to release calcium ions into cytosol
calcium binds to troponin to change its shape

14. Excitation Contraction Coupling
position of tropomyosin is altered
binding sites on actin are exposed
actin and myosin molecules bind

15. Sliding Filament Model of Muscle Contraction
When cross-bridges pull on actin the sarcromeres shorten, thick and thin filaments slide past one another

16. Cross-bridge Cycling
When myosin is pulling on the actin, ATP is broken down into ADP and phosphate.

17. Relaxation
acetylcholinesterase – enzyme that rapidly decomposes acetylcholine remaining in the synapse
As a result:
muscle impulse stops
stimulus to sarcolemma and muscle fiber membrane
ceases
calcium moves back into sarcoplasmic reticulum
myosin and actin binding prevented
muscle fiber relaxes

18. Major Events of Muscle Contraction and Relaxation

19. Energy Sources for Contraction
1) Creatine phosphate 2) Cellular respiration
creatine phosphate – stores energy that quickly converts ADP to ATP

20. Oxygen Supply and Cellular Respiration
Anaerobic Phase
glycolysis
occurs in cytoplasm
produces little ATP
Aerobic Phase
citric acid cycle
electron transport chain
occurs in the mitochondria
produces most ATP
myoglobin stores extra oxygen

21. Oxygen Debt
Oxygen debt – amount of oxygen needed by liver cells to use the accumulated lactic acid to produce glucose
oxygen not available
glycolysis continues
pyruvic acid
converted to lactic acid
liver converts lactic
acid to glucose

22. Muscle Fatigue inability to contract commonly caused from
decreased blood flow
ion imbalances across the sarcolemma
accumulation of lactic acid
cramp – sustained, involuntary muscle contraction

23. Heat Production by-product of cellular respiration
muscle cells are major source of body heat
blood transports heat throughout body

24. Muscular Responses Threshold Stimulus
minimal strength required to cause contraction
Recording a Muscle Contraction
twitch
latent period
period of contraction
period of relaxation
refractory period
all-or-none response

25. Summation process by which individual twitches combine
produces sustained contractions
can lead to tetanic contractions

26. Recruitment of Motor Units
recruitment - increase in the number of motor units activated
whole muscle composed of many motor units
more precise movements are produced with fewer
muscle fibers within a motor unit
as intensity of stimulation increases, recruitment of motor units continues until all motor units are activated

27. Sustained Contractions
smaller motor units (smaller diameter axons)
- recruited first
larger motor units (larger diameter axons)
- recruited later
produce smooth movements
muscle tone – continuous state of partial contraction

28. Types of Contractions isotonic – muscle contracts and changes length
isometric – muscle contracts but
does not change length

29. Fast and Slow Twitch Muscle Fibers
Fast-twitch glycolytic fibers (type IIa)
white fibers (less myoglobin)
poorer blood supply
susceptible to fatigue
“white meat”
Slow-twitch fibers (type I)
always oxidative
resistant to fatigue
red fibers
most myoglobin
good blood supply
many mitochodria
“dark meat”
Fast-twitch fatigue-resistant fibers (type IIb)
intermediate fibers
oxidative
intermediate amount of myoglobin
pink to red in color
resistant to fatigue

30. Smooth Muscle Fibers Compared to skeletal muscle fibers shorter
single, centrally located nucleus
elongated with tapering ends
myofilaments randomly organized
lack striations
lack transverse tubules
sarcoplasmic reticula not well developed
2 types
Visceral – walls of hollow organs
Multiunit – iris of eye & blood vessesels

31. Smooth Muscle Contraction
Resembles skeletal muscle contraction
interaction between actin and myosin
both use calcium and ATP
both are triggered by membrane impulses
Different from skeletal muscle contraction
smooth muscle lacks troponin (replaced with calmodulin)
two neurotransmitters (acetlycholine and norepinephrine)
affect smooth muscle
hormones affect smooth muscle
stretching can trigger smooth muscle contraction
smooth muscle slower to contract and relax
smooth muscle more resistant to fatigue

32. Cardiac Muscle muscle fibers joined together by intercalated discs
located only in the heart
muscle fibers joined together by intercalated discs
fibers branch
network of fibers contracts as a unit
self-exciting and rhythmic
longer refractory period than skeletal muscle

33. Characteristics of Muscle Tissue

34. Skeletal Muscle Actions
origin – immovable end
insertion – movable end
prime mover (agonist) – primarily responsible for movement
synergists – assist prime mover
antagonist – resist prime mover’s action and cause movement in the opposite direction

35. Body Movement Four Basic Components of Lever rigid bar – bones
fulcrum – point on which bar moves; joint
object - moved against resistance; weight
force – supplies energy for movement; muscles

36. Levers and Movement

37. Life-Span Changes myoglobin, ATP, and creatine phosphate decline
by age 80, half of muscle mass has atrophied
adipose cells and connective tissues replace muscle tissue
exercise helps to maintain muscle mass and function

38. Clinical Application Myasthenia Gravis autoimmune disorder
receptors for ACh on muscle cells are attacked
weak and easily fatigued muscles result
difficulty swallowing and chewing
ventilator needed if respiratory muscles are affected
treatments include
drugs that boost ACh
removing thymus gland
immunosuppressant drugs
antibodies

39. More Clinical Applications
Moebius Syndrome
“walking corpse syndrome” or “stone face”
Tendinitis
Muscular Dystrophy
Poliomyelitis
Tetanus and Botulism
Lou Gehrig's disease
amyotrophic lateral sclerosis (ALS)

40. Major Skeletal Muscles

41. Major Skeletal Muscles

42. Muscles of Facial Expression

43. Muscles of Mastication

44. Muscles of Facial Expression and Mastication

45. Muscles That Move the Head and Vertebral Column

46. Muscles That Move the Head and Vertebral Column

47. Muscles That Move the Pectoral Girdle

48. Muscles That Move the Pectoral Girdle

49. Muscles That Move the Arm

50. Muscles That Move the Arm

51. Muscles That Move the Arm

52. Muscles That Move the Forearm

53. Muscles That Move the Forearm

54. Muscles That Move the Forearm

55. Cross Section of the Forearm

56. Muscles That Move the Hand

57. Muscles That Move the Hand

58. Muscles of the Abdominal Wall

59. Muscles of the Abdominal Wall

60. Muscles of the Pelvic Outlet

61. Muscles of Pelvic Outlet

62. Muscles That Move the Thigh

63. Muscles That Move the Thigh

64. Muscles That Move the Thigh

65. Muscles That Move the Leg

66. Muscles That Move the Leg

67. Muscles That Move the Leg

68. Muscles That Move the Leg

69. Muscles That Move the Foot

70. Muscles That Move the Foot

71. Muscles That Move the Foot

72. Cross-bridge Cycling
myosin cross-bridge attaches to actin binding site
myosin cross-bridge pulls thin filament
ADP and phosphate released from myosin
new ATP binds to myosin
linkage between actin and myosin cross-bridge break
ATP splits
myosin cross-bridge goes back to original position