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47 Cards in this Set
- Front
- Back
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functions of muscle (4)
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heat generation
posture movement stabilizing joints |
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characteristics of muscle cells (4)
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excitability
contractibility extensibility elasticity |
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connective tissue of skeletal muscle (3)
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1. epimysium - dense irregular CT
2. perimysium - fibrous CT 3. endomysium - reticular CT |
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direct attachment (skeletal muscle)
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epimysium fused with periosteum (bone)
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indirect attachment (skeletal muscle)
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epimysium connected to bone by tendon or aponeurosis (dense CT)
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specialized components of sarcoplasm (2)
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glycosomes - store glycogen
myoglobin - oxygen storing pigment (red) |
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H-zone
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central light zone of dark A band (thick filaments only)
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M-line
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biseects H-zone of dark A band
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Z-disc
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bisects light I-bands; connects sarcomeres together
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thick filaments
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bundles of myosin
tails=2 interwoven heavy meromysin chains heads=2 connected light meromysins |
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thin filaments (of skeletal muscle)
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backbone of actin molecules
tropomyosin - spirals around backbone tropinin - acts as hinge (ITC) |
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tropomyosin
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spirals around actin core of thin filaments
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tropinin
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"hinge" of thin filaments
TnI - binds to actin (inhibitory) TnT - binds to tropomyosin TnC - binds to calcium |
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terminal cisternae
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ends of SR; release Ca when stimulated by impulses from T-tubules
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T-tubules
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form triads with terminal cisternae; conduct impulses that signal release of Ca from TC
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sliding filament hypothesis
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contraction due to filaments sliding past each other
dark a band widens, h-zone disappears |
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Phase 1 - muscle fiber stimulation by motor neuron (5)
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1. AP arrives at axon terminal of neuromuscular junction
2. ACh released 3. Ion permeability of sarcolemma changes 4. local change in membrane voltage (depolarization) 5. AP ignited in sarcolemma |
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Phase 2 - E-C coupling (4)
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1. AP travels across sarcolemma
2. AP travels along T-tubules down into sarcomere 3. Ca binds to troponin, active sites of actin exposed 4. myosin heads bind to actin; contractions begin |
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cross bridge cycle (4)
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1. cross bridge formation
2. power stroke (ADP released) 3. cross bridge detachment 4. cocking of myosin head (ATP hydrolyzed) |
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Requirements to maintain muscle contraction (2)
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1. high sarcoplasmic [Ca]
2. constant supply of ATP |
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phases of muscle twitch (3)
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latent period
period of contraction period of relaxation |
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wave summation
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graded muscle responses to changes in stimulus FREQUENCY
muscle still partially contracted when next stimulus arrives |
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tetanus
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sustained contraction of summated twitches
unfused and fused |
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recruitment (or multiple motor unit summation)
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higher intensity = more unitis activated
helps prevent fatigue |
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asychronous activation
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recruitment; some motor units rest while others contract
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isotonic contraction
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tension>load
tension constant, length decreases thin filaments sliding 1. concentric (shortening) 2. eccentric (lengthening) |
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concentric isotonic contraction
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muscle shortens as it produces tension
ex-picking up heavy object |
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eccentric isotonic contraction
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muscle lengthens as it produces tension
ex-setting down heavy object more force than conceaerntric |
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isometric contraction
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tension<load
tension increases, length constant cross bridges generating force but not moving thin filaments ex-muscle tone |
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atp generation-aerobic metabolism
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low intensity, long (unlimited) duration
32 ATP/glucose dependent on O2 from blood |
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factors affecting muscle fatigue (3)
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depletion of fuels/CP
ionic imbalances lactic acid build up (if anaerobic) |
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cotractures
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state of continuous contraction
result of complete ATP depletion crossbridges unable to detach |
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brain regulation of metabolism 34)
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1. monitors chemical changes in blood
2. monitors degree of muscle stretch 3. monitors body temp |
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steps to restoring cellular metabolic environment (5)
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1. decrease temp
2. restore glycogen stores 3. restore CP (via ox) 4. restore Oxygen stores 5. detoxify lactic acid in liver (Cori Cycle) |
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ability of muscle to do work depends on... (3)
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force
velocity duration |
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factors affecting force (4)
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# muscle fibers
size of muscle fibers frequency of stimulation degree of muscle stretch |
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hypertrophy
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increases sacromere size, adds myofilaments
from hormones, androgens, or exercise |
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internal tension
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generated by sarcomeres (contractile units); force generated by cross bridges
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external tension
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CT (noncontractile units) stretch and exert tension from sarcomeres to load
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length-tension relationship
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amt of force depends on length of resting muscle
produce max force when stimulated at 100% resting length |
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fascicle arrangements of muscle (5)
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circular sphincters (eye)
parallel (sartorius) convergent fusiformpenate (feather) uni-, bi-, and multipennate |
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smooth muscle contraction
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1. Ca enters cytosol from ECF
2. Ca binds to calmodulin 3. act calmodulin activates MLCKE 4. MLCKE phosphorylates myosin (ATP-->ADP) 5. activated myosin forms cross bridges with actin |
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regulation of smooth muscle contraction (3)
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spontaneous depolarization
mechanical stimulation hormonal factors |
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stress-release response
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smooth muscle; allows hollow organ to expand and fill (mech. stimulation)
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diffuse junctions
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junctions where neurotransmitters from viscosities diffuse to smooth muscle
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single unit smooth muscle
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linked by electrical gap junctions; entire sheet contracts together
contraction initiated by stretch/hormonal factors (intestine/uterus) |
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multiunit smooth muscle
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not electrically linked; independent contraction; initiated by stretch/hormonal factors (BVs, airway, eye muscles)
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