NURS 163 Chapter Notes - Chapter 7: Caveolae, Muscle Tone, Cytoskeleton
Study Guide 7: Muscles
1. Four functions of muscular system:
1) Produce movement
2) Maintain posture
3) Stabilize joints
4) Thermogenesis
2. Three types of muscle tissue:
1) Skeletal
a. Voluntary
b. Striated
c. Covers skeleton
2) Cardiac
a. Involuntary
b. Striated
c. Heart
3) Smooth
a. Involuntary
b. Non-striated
c. Internal organs
3. Four functional characteristics of muscle:
1) Excitability: response to stimulus
2) Contractility: tension generated= force production
3) Extensibility: stretch/lengthened by outside force w/o damaging
tissue
4) Elasticity: recoiling of muscle after extension
4. Muscle’s most distinguishing, unique characteristic: only tissue w/
contractility
5. Protective properties of muscle: elasticity
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6-9. Anatomy of muscle:
A. Myofibrils: Contractile elements of muscle fiber
B. Muscle fiber: 100s-1000s myofibrils
C. Endomysium: areolar CT surrounding each muscle fiber
D. Fascicles: group of muscle fibers
E. Perimysium: fibrous CT surrounding each fascicle
F. Sarcoplasm: cytoplasm that surrounds fascicles
G. Epimysium: dense regular CT surrounding entire muscle
a. Blends w/ deep/superficial fascia
10. Nerves & Blood supplying skeletal muscle:
A. Branch through CT sheaths (--mysium)
b. 1 nerve
c. 1 artery
d. 1+ veins
11-12. Indirect vs. Direct muscle attachments:
A. Direct: Epimysium CT fuses w/ periosteum/perichondrium
B. Indirect: Epimysium CT extends beyond muscle as… and anchors
to bone/cartilage/other muscle fascia.
a. Tendon: rope-like
b. Aponeurosis: sheet-like
13. Sharpey’s fibers: anchoring to bone for tendons, ligaments, muscle
14. Indirect attachments: what tissues transmit pulling forces from muscle
→ bone?
A. Endomysium
B. Perimysium
C. Epimysium
15-16. Four arrangements of fascicles/fibers:
1) Circular: concentric muscle rings (i.e. sphincter)
2) Convergent: broad origin, fascicles converge toward single
tendon insertion
a. Greatest force production
3) Parallel: thin & long; fibers run parallel w/ long axis of muscle
a. Longer fibers allow muscle to shorten more
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4) Pennate: short fascicles attach obliquely to central tendon
a. Most muscle fibers= very powerful
b. Unipennate: insert → 1 side of tendon
c. Bipennate: inset → opposite sides of tendon
d. Multipennate: many insertions around tendon
17. Lever operating at mechanical advantage or disadvantage:
1) Mechanical advantage: “power lever”
a. Load close to fulcrum, effort far from fulcrum
b. Small effort, large distance = large load, small distance
c. EX: car jack
2) Mechanical disadvantage: “speed lever”
a. Load far from fulcrum, effort close to fulcrum
b. Load moved rapidly over large distance, wide ROM
c. EX: shoveling
18. Lever system in body:
A. Third class lever: effort between load and fulcrum
19&21. Chemical composition of muscle fibers:
A. 75% water (weight)
B. 20% proteins: contractile or enzymes
C. 5% salts, pigments, substrates
20. Function of myoglobin:
A. Red pigment
B. Transfers O2 from blood → mitochondria
C. Single stranded molecule
D. Higher concentration in muscles w/ higher O2 needs
22&33. Adapting organelles for skeletal muscle function:
A. Nucleus:
a. Multinucleated muscle fibers
b. Peripherally located
c. Genes direct contraction w/ protein enzymes
B. Mitochondria:
a. Many per cell
b. Create ATP for contraction
c. In rows near the contractile proteins
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Document Summary
Contraction effects on a band, i band, h zone, z discs, sarcomere length: a band: same length, i band: gets smaller, h zone: gets smaller, z discs: closer together, sarcomeres: shorten. Role of ca2+ & regulatory proteins in sliding filament mechanism: ca2+ binds to troponin= pulls tropomyosin off actin, allows myosin to bind to actin. *process will repeat until atp or ca2+ are depleted. **crossbridge cycling repeats until atp or ca2+ are depleted (sarcoplasm ca2+ levels high: atp-dependent ca2+ pumps of sr terminal cisternae re- sequester ca2, =sarcoplasm ca2+ levels fall = tropomyosin moves back over active site. Atp"s important roles in all of this: atp breakdown = myosin cocks it"s head high energy position, atp attachment = myosin to detach from actin, atp pumps pump ca2+ back sr terminal cisternae. Muscle fatigue: inability to contract muscle, despite receiving stimuli, contributing factors, problems in excitation-coupling, problems @ nmj, ionic imbalances, k lost from muscle cells, accumulates in t tubules.
