1. Warm-Up
Based on what you know about Latin root words, what do you think these terms refer to?
Sarcomere
Sarcoplasm
Myofibril
Epimysium
Perimysium
Endomysium
What structure connects muscle to bone?

2. Warm-Up
What is the organization of a skeletal muscle from the largest to the smallest structures?
Draw and label the parts of a sarcomere. Be sure to include the thick & thin filaments, I band, A band, and Z lines.

3. Warm-Up Describe what happens at the neuromuscular junction.
How would a drug that blocks acetylcholine (ACh) release affect muscle contraction?
Which of the following pictures below shows a contracted muscle? Explain your answer.

4. Warm-Up Put the following events in muscle contraction in order:
Calcium binds to troponin  changes shape  myosin binding sites exposed on actin
Myosin head pivots and pulls actin filament toward M line
ATP attaches to myosin and cross-bridge detaches
Action potential travels down sarcolemma along T-Tubules
Myosin cross-bridge forms with actin
Calcium is released from sarcoplasmic reticulum (SR)

5. Warm-Up
Jay is competing in a chin-up competition. What types of muscle contractions are occurring in his biceps muscles:
immediately after he grabs the bar?
as his body begins to move upward toward the bar?
when his body begins to approach the mat?
When a suicide victim was found, the coroner was unable to remove the drug vial from his hand. Explain.

6. Chapter 8 Muscular System 8 - 6
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
8 - 6

7. B. The three types of muscle in the body are: 1. Skeletal – voluntary
Introduction:
A. All movements require muscle which are organs using chemical energy to contract.
B. The three types of muscle in the body are:
1. Skeletal – voluntary
a. Multinucleated
b. Striation
2. Smooth – involuntary
a. Single nuclei
b. No Striations
3. Cardiac – involuntary
b. Intercalated discs and striations
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9. Structure of a Skeletal Muscle
A. Each muscle is an organ, comprised of:
1. skeletal muscle tissue
2. connective tissue
3. nervous tissue
4. blood
Prefixes:
My/myo  muscle
Sarco  flesh
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10. B. Connective Tissue Coverings
1. Fascia – dense connective tissue that surrounds and separates each muscle
2. Tendons – extend past fascia; connect muscle to bone (via periosteum)
3. Aponeuroses – broad sheets of connective tissue that connect muscle
4. Epimysium – connective tissue that surrounds each whole muscle
5. Perimysium – surrounds individual bundles (fascicles) within each muscle
6. Endomysium – connective tissue covering each muscle cell (fiber)
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11. 8 - 11

12. Study Analogy representing the fascia.
Pretend you are going to play a joke on someone and give them 100 pencils. The pencils will represent muscle fibers. First you wrap each individual pencil in tissue paper (dense tissue paper of course!). This would be endomysium. Then you take about 10 pencils in a bundle (a fascicle) and wrap them in paper (perimysium). After that you take all the bundles and wrap them in gift wrap (epimysium). But you are going to mail this joke, so you also have to wrap it in brown paper
representing the fascia.
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13. C. Skeletal Muscle Fibers
1. Each muscle fiber is a single, long, cylindrical muscle cell.
2. Beneath the sarcolemma (cell membrane) lies sarcoplasm (cytoplasm) with many mitochondria and nuclei; the sarcoplasm contains myofibrils  key role in muscle contractions and made up of:
a. Myosin  Thick protein filaments
b. Actin  Thin protein filaments
c. The organization of these filaments produces striations.
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14. 3. Sarcomere extends from Z line to Z line.
a. I bands (light bands) made up of actin filaments are anchored to Z lines.
b. A bands (dark bands) are made up of overlapping thick and thin filaments.
c. In the center of A bands is an H zone, consisting of myosin filaments only.
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15. 8 - 15

16. BOTH ACTIVATE THE MUSCLE CONTRACTION MECHANISM
4. Sarcoplasm composed of:
a. Sarcoplasmic reticulum (SR) – surround each myofibril and run PARALLEL to it
b. Transverse (T) tubules – run perpendicular to SR; passes all way through myofibril
1. lies between two cisternae of SR
2. open to the outside of the muscle fiber
BOTH ACTIVATE THE MUSCLE CONTRACTION MECHANISM
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17. 8 - 17

18. D. Neuromuscular Junction (NMJ)
1. Site where the motor neuron and muscle fiber meet
a. Motor neuron  nerve cell that connects to a muscle fiber
b. Axon  appendage of nerve cell
c. Motor end plate  area where nuclei and mitochondria are abundant
d. Synaptic vesicles  store neurotransmitters (ex. Acetylcholine)
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19. E. Motor Units
1. Collective name for the motor neuron and muscle fiber working together to cause a muscle contraction
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20. 8 - 20

21.  Skeletal Muscle Contraction
A. Shortening of sarcomeres and pulling of the muscle against its attachments
B. Role of Myosin and Actin
1. Myosin  protein consists of cross-bridges
2. Actin  protein with myosin binding sites
a. Tropomysosin and Troponin two proteins of the actin filament
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22. 8 - 22

23. 3. Sliding filament theory
a. Myosin cross-bridge attaches to the binding site on the actin filament and bends  pulling on the actin filament
b. It then releases and attaches to the next binding site on the actin  pulling again.
4. Energy from the conversion of ATP to ADP is provided to the cross-bridges from the enzyme ATPase, causing them to be in a “cocked” position.
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24. C. Stimulus for Contraction
1. The motor neuron must release the neurotransmitter acetylcholine from its synaptic vesicles into the synaptic cleft in order to initiate a muscle contraction.
2. Protein receptors in the motor end plate detect the neurotransmitters, and a muscle impulse spreads over the surface of the sarcolemma and into the T tubules, where it reaches the sarcoplasmic reticulum.
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25. 3. Upon receipt of the muscle impulse, the sarcoplasmic
3. Upon receipt of the muscle impulse, the sarcoplasmic reticulum releases its stored calcium to the sarcoplasm of the muscle fiber.
4. The high concentration of calcium in the sarcoplasm interacts with the troponin and tropomyosin molecules, which move aside, exposing the myosin binding sites on the actin filaments.
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26. 5. Myosin cross-bridges now bind and pull on the actin
5. Myosin cross-bridges now bind and pull on the actin filaments, causing the sarcomeres to shorten.
6. After the nervous impulse has been received, acetylcholinesterase rapidly decomposes the acetylcholine.
7. Then, calcium is returned to the sarcoplasmic reticulum, and the linkages between myosin and actin are broken.
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27. 8 - 27

29. Study Analogy: Think of a very familiar love story
Study Analogy: Think of a very familiar love story. The actin and myosin are in love and would love to bind (keep it clean, think kiss). However, the actin is being guarded by the troponin and tropomyosin (T-T complex), perhaps they are her parents or guardians? But someone is looking out for the love birds, maybe a fairy godmother? They send a messenger in the form of a nerve impulse. This messenger isn’t someone allowed in the house, so they send a second messenger (acetylcholinesterase) by way of the trusty T-tubules. This messenger releases a distractor (aka calcium). Pretend this is a belly dancer or someone from Publisher’s clearing house or some other such distraction.
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30. While the T-T complex is so occupied, actin and myosin are free to bind. Of course this takes a lot of energy (who said love was easy?), but the messenger has only been paid for so long (destroyed by acetylcholinesterase) and the distractor can only dance (or whatever) for so long and has to leave (calcium returns to sarcoplasmic reticulum). Thus, the linkages are broken and they cannot live happily every after. But wait, another impulse may come along at any time!
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31. D. Energy Sources for Contraction
1. ATP  limited supply (only for short timed muscle contractions) and so must often be regenerated
2. Creatine phosphate which stores excess energy released by the mitochondria… present to regenerate ATP from ADP and phosphate.
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32. E. Oxygen Supply and Cellular Respiration
1. Hemoglobin in red blood cells carries oxygen to muscle
a. Iron (Fe)  high affinity for oxygen
b. Anemia  low Fe in blood
2. Myoglobin stores oxygen in muscle tissue
a. Reduces need for continuous blood supply
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33. F. Oxygen Debt 1. Lacking oxygen due to strenuous exercise
2. Convert to anaerobic respiration
a. Pyruvic acid to lactic acid
3. Must be repaid  may take several hours
a. Equal amounts of oxygen to convert lactic acid back into glucose
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34. G. Muscle Fatigue and Cramps
1. Fatigue  Loss of ability to contract during strenuous exercise
a. Arises from the accumulation of lactic acid in the muscle  lower pH due to accumulated lactic acid  prevents the muscle from contracting
2. Muscle cramp occurs due to a lack of ATP required to return calcium ions back to the sarcoplasmic reticulum so muscle fibers can relax
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35. 3. Rigor Mortis
A. Partial contraction that fixes the joints
B. Increase in calcium b/c membrane is more permeable
1. Decrease in ATP
2. Actin and myosin remain contracted - cannot relax
3. Muscle decomposition  relaxation

36. H. Heat Production
1. Contraction of skeletal muscle  important source of heat for the body
2. Energy produced through cellular respiration  lost as heat (another source of heat for the body)
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37. 2. Followed by a period of contraction and a period of relaxation
 Muscular Responses
A. Threshold Stimulus
1. A muscle fiber remains unresponsive to stimulation unless the stimulus is of a certain strength  threshold stimulus
B. Latent Period
1. Time delay between when the stimulus is applied and when the muscle contracts  less than second
2. Followed by a period of contraction and a period of relaxation

38. C. All-or-None Response
1. When a muscle fiber contracts, it contracts to its full extent (all-or-none response); it cannot contract partially.
D. Recruitment
1. Increase in # of motor units activated
E. Tetanic contraction  TETANUS
1. Forceful and lacks even partial relaxation
F. Sustained Contraction
1. Muscle Tone
G. Tonic Contraction
1. Holds muscles in place and counteracts gravity
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39. E. Fast Twitch Muscle Fibers
1. Used during strenuous exercise  weight lifting can exert more than 75% of max. tension
2. Glycolytic and fatigable
F. Slow Twitch Muscle Fibers
1. Muscle contracts with low intensity  swimming or running
2. Oxidative and fatigue-resistant

40. 1. Elongated with tapered ends 2. Lack striations 3. Single nuclei
 Smooth Muscles
A. Smooth Muscle Fibers
1. Elongated with tapered ends
2. Lack striations
3. Single nuclei
4. Visceral
a. Rhythmicity (pattern or repeated contractions)  Peristalsis (wave-like motion)
5. Ex. Hollow organs
6. Actin and myosin
a. slower to contract and relax
b. Neurotransmitters
1. Acetylcholine
2. Norepinephrine
3. Hormones play a role too
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41. B. Striated cells join end to end C. Single Nuclei D. Actin and myosin
Cardiac Muscle
A. Heart only
B. Striated cells join end to end
C. Single Nuclei
D. Actin and myosin
E. Intercalated disks
1. Myofibril attachment
2. Transmit rapidly (self-exciting)  whole structure contracts
3. All or none response
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43.  Skeletal Muscle Actions A. Origin and Insertion
1. Origin  immovable end of muscle
2. Insertion  movable end
3. Contraction  insertion pulled toward origin
4. Some muscles have more than one insertion or origin
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44. B. Interaction of Skeletal Muscles
1. Prime mover  main muscle doing work
2. Synergist  “helpers” contract and assist prime mover
3. Antagonist  muscles resisting prime mover’s action
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45.  Major Skeletal Muscles
A. Muscles are named according to any of the following criteria:
1. size
2. shape
3. location
4. action
5. number of attachments
6. direction of its fibers
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46. Directions
The following terms refer to the direction the muscle fibers run in relation to the midline.

47. Rectus
Parallel to the midline

48. Transverse
Perpendicular to the midline

49. Oblique
Diagonal to the midline

50. Size
Relative to other muscles in that group

51. Maximus
Largest

52. Minimus
Smallest

53. Longus or Longissimus
Longest

54. Latissimus
Widest; means “broadest muscle on the back”

55. Magnus
Large

56. Major
Larger

57. Minor
smaller

58. Vastus
great

59. Shape
General shape of the muscle

60. Deltoid
Triangle

61. Trapezius
Trapezoid

62. Serratus
Saw-toothed

63. Rhomboid
Diamond shaped

64. Orbicularis
Circular

65. Pectinate
Comb-like

66. Piriformis
Pear shaped

67. Platys
Flat

68. Quadratus
square

69. Gracilis
slender

70. Action
Based on the action the muscle performs

71. Flexor/Extensor Flexor – decreases the angle between bones
Extensor – increases the angle between bones

72. Abductor/Adductor Abductor – moves a bone away from the midline
Adductor – moves a bone toward the midline

73. Levator/Depressor Levator – elevates body part
Depressor – lowers body part

74. Supinator/Pronator Supinator – turns palms up
Pronator – turns palms down

75. Sphincter
Decreases the size of an opening

76. Tensor
Makes a body part rigid

77. Number of Origins Biceps – 2 heads Triceps – 3 heads
Quadriceps – 4 heads

78. Location Muscles named for the structures that they are by.
Examples include the sternocleidomastoid muscle (runs from the sternum across the clavicle to the mastoid process) and the temporalis (near the temporal bone)

79. B. Muscles of Facial Expression
1. Major muscles include epicranius, orbicularis oculi,
orbicularis oris, and buccinator
C. Muscles of Mastication
1. Chewing muscles include masseter, temporalis, and zygomaticus
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80. D. Muscles that Move the Head
1. Major muscles include sternocleidomastoid, splenius capitis, and semispinalis capitis
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81. E. Muscles that Move the Pectoral Girdle
1. The chest and shoulder muscles move the scapula
2. Major muscles include trapezius, rhomboideus major, levator scapulae, serratus anterior, and pectoralis minor
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82. 2. Flexors: coracobrachialis and pectoralis major
F. Muscles that Move the Arm
1. Muscles connect the arm to the pectoral girdle, ribs, and vertebral column, making the arm freely movable
2. Flexors: coracobrachialis and pectoralis major
3. Extensors: teres major and latissimus dorsi
4. Abductors: supraspinatus and deltoid
5. Rotators: subscapularis, infraspinatus, and teres minor
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83. G. Muscles that Move the Forearm
1. Arise from the humerus or pectoral girdle and connect to the ulna and radius
2. Flexors: biceps brachii, brachialis, and brachioradialis
3. Extensor: triceps brachii
4. Rotators: supinator, pronator teres, and pronator quadratus
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84. H. Muscles that Move the Wrist, Hand, and Fingers
1. Muscles originating from the distal humerus, and the radius and ulna
2. Flexors: flexor carpi radialis, flexor carpi ulnaris, palmaris longus, and flexor digitorum profundus
3. Extensors: extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, and extensor digitorum
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85. 1. Connects the rib cage and vertebral column to the pelvic girdle
I. Muscles of the Abdominal Wall
1. Connects the rib cage and vertebral column to the pelvic girdle
a. Band of tough connective tissue, the linea alba, extending from the xiphoid process to the symphysis pubis, serves as an attachment for certain abdominal wall muscles
2. These four muscles include:
a. external oblique, internal oblique, transverse abdominis, and rectus abdominis
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86. J. Muscles of the Pelvic Outlet
1. Superficial urogenital diaphragm fills the space within the pubic arch, and the deeper pelvic diaphragm forms the floor of the pelvic cavity
2. Pelvic diaphragm includes the levator ani
3. Urogenital diaphragm includes: superficial transversus, perinei, bulbospongiosus, and ischiocavernosus
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87. K. Muscles that Move the Thigh
1. Muscles that move the thigh are attached to the femur and to the pelvic girdle
2. Anterior group includes: psoas major and iliacus
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88. L. Muscles that Move the Leg
1. Connects the tibia or fibula to the femur or pelvic girdle.
2. Flexors: biceps femoris, semitendinosus, semimembranosus, and sartorius
3. Extensor: quadriceps femoris group  made up of four parts: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius
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89. 3. Plantar flexors: gastrocnemius, soleus, and flexor digitorum longus
M. Muscles that Move the Ankle, Foot, and Toes
1. Muscles that move the foot are attached to the femur, fibula, or tibia, and move the foot upward, downward, or in a turning motion
2. Dorsal flexors: tibialis anterior, peroneus tertius, and extensor digitorum longus
3. Plantar flexors: gastrocnemius, soleus, and flexor digitorum longus
4. Invertor: tibialis posterior
5. Evertor: peroneus longus
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