Chap. 6: Muscle Tissue
Review your quizzes!!
Muscle Ultrastructure https://www.youtube.com/watch?v=Ktv-CaOt6UQ
Sliding Filament Video https://www.youtube.com/watch?v=EdHzKYDxrKc
Neuromuscular junction video https://www.youtube.com/watch?v=t9sjIByjw70
Differences between the three categories of muscles
 Skeletal: Voluntary/Multiple nuclei/Striated (striped)/Moves skeleton
 Cardiac: Involuntary/Single nucleus/Striated/Moves blood
 Smooth: Involuntary/Single nucleus/Non-striated? Moves food
Functions of Skeletal muscle
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Movement of skeleton
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Generated body heat
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Stabilizes joint
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Maintain posture
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Protects organs in abdomen
Anatomy/Organization of Muscle
 Myofilaments: Actin= thin filament
Myosin = thick filament
 Myofibrils: Composed of myofilaments; fills each individual muscle fiber.
 Muscle fibers (cells) covered/wrapped by endomysium
 Fascicle bundles of muscle fibers wrapped by perimysium
 Muscle: bundle of fascicles held together by epimysium.
 Connective Tissue wrappings: Epimysium/perimysium/endomysium: insulates and protects.
 Tendon end of epimysium that covers entire muscle and attaches to bone for movement
Skeletal Muscle Fibers
 Actin/myosin: responsible for ACTUAL contraction by sliding over one another. Their interaction is what expends
energy in the form of ATP.
o Actin is the thin myofilament
o Myosin is the thick myofilament
 Sarcomere: contractile unit of muscle fiber; spans Z-line to Z-line protein fibers.
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Contraction
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Sketch a sarcomere and label. What occurs at the sarcomere as a
muscle contracts?
Why do we call contraction of the sarcomere the Sliding Filament Theory of muscle contraction?
o Because the interaction between actin and myosin causes a sliding of the filaments over one another
producing a shortening of the sarcomere upon contraction and a sliding/lengthening of the sarcomere upon
relaxation.
Neuromuscular junction: when motor neuron and muscle cell membrane come together
Neurotransmitter/Ach: allows for chemical transmission of impulse from neuron to muscle membrane
Action potential: the movement of ions across the neuron and muscle cell membrane.
Calcium: ion needed to allow actin and myosin to come together.
***LOOK at your Quiz to place the events in the correct order.***
Aerobic Metabolism: uses oxygen to convert glucose into ATP. MOST EFFICIENT/TAKES THE LONGEST
 Steps?
1. Glycolysis = breaking sugar into smaller compound. Creates 2 ATP.
2. Kreb Cycle = continual breakdown of former glucose molecule in the presence of oxygen to form 2 ATP
3. Electron Transport Chain = movement of hydrogen across the MITOCHONDRIAL membrane produces ~32 ATP molecule.
 Amount of ATP See above
 Organelle activity MITOCHONDRIA
 Efficiency See above
Anaerobic Metabolism: occurs in the absence of oxygen. Converts to anaerobic when needs are not met any longer through aerobic
respiration. LESS EFFICIENT/OCCURS QUICKLY
 Steps?
1. Glycolysis = same as above. Breaks sugar into smaller compound. Creates 2 ATP
2. Lactic Acid Fermentation = creates 2 ATP and lactic acid as a byproduct that remains in between actin and myosin,
causing pain during contraction.
 Amount of ATP? See above
 Efficiency? See above
Creatine Phosphorylation: occurs in the cytoplasm of the muscle fibers. As ATP is used, releasing the stored energy from the last 2
phosphate molecules, available phosphate can then be added to the ADP to produce ATP. The available phosphate groups comes
from liberated ATP and from diet supplements, such as creatine phosphate.
 Steps? Only 1, addition of a phosphate group.
 Amount of ATP? Depends on how much ADP is available for phosphorylation.
 Efficiency? Only as efficient as the athlete is.
Rules for Naming Muscles
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Location: regional anatomy (abdominal), bone adjacent to (femoral).
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Muscle action: flexion, extension, etc.
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Number of attachment points: bi- tri- quad-
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Directional anatomy: superficial, anterior, dorsal
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Shape (deltoid) or size (minimus, maximus)
Know muscle diagrams.
Study muscle disease notes