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skeletal muscle
striated, voluntary control, temperature management, multi-nucleated
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cardiac muscle
heart, striated, involuntary, autorhythmic pacemaker
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epimyseum
DCT that covers a whole muscle
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perimyseum
DCT that covers fascicles in a muscle (10-100 plus myofibrils each)
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endomysium
separates myofibrils from each other
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motor neurons
nerves that stimulate muscle contraction
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hypertrophy
thickening of muscle fibers
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hyperplasia
more muscle fibers added
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sarcolemma
the plasma membrane of the myofibril
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transverse tubules
tunnels in sarcolemma that help to ensure uniformity in action
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thin filaments
8 nm diameter (actin)
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thick filament
16 nm (myosin)
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sarcomere
structural unit of a myofibril
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z discs
dense protein material that separates each sarcomere
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A band
length from z disc to z disc in sarcomere
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h zone
only thick filaments in the center of sarcomere
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I band
z-discs of sarcomeres
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myosin
motor protein converts chemical in mechanical energy ( have myosin heads that control the actin)
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Actin
helix shaped thin filament which has myosin binding site for globular head
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tropomyosin and troponin
- tropomyosin relaxes muscle by blocking actin binding site from myosin head
- troponin holds tropomyosin in place
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NMJ (neuromuscular junction)
point between synapse bulb and the muscular receptors (neurotransmiters send message from nerve to muscle)
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titin
secures thick filament position
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dystrophin
helps to generate tension by linking actin to intergral membrane proteins in the sarcolemma
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acetylcholine
neurotransmitter of motor neurons
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synaptic vesicles
hold acetylcholine
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Calcium ion release channels
SR releases these ions upon contraction in order to combine with troponin and get rid of the tropomyosin that inhibits movement of myosin to actin
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Contraction cycle
- 1. ATP splits- ATP is removed a phospate to gain energy
- 2 myosin attaches to actin to release phosphate
- 3. powerstroke- force of contraction generated
- 4. myosin head will atach to another atp provided that it is available
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Relaxation
- Achase helps to break down acetylcholine which stops Ca 2 plus production
- active transport pumps open to force calcium back
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twitch contraction
brief contraction of all the muscle fibers in a motor unit in response to a single nerve impulse
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latent period
delay between stimulus and actual contraction
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wave summation
stimuli in close succession that allow for larger contractions
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unfused vs fused tetanus
stimulus comes but slower vs. coming very quickly
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tone
muscle tautness caused by weak contractions of motor units- stability
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isotonic contraction
no change in tension, change in length- moving stuff
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concentric isotonic
shortens to pull on another structure, produce movement and reduce angle of joint - picking up book
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eccentric
length increases - biceps to help lower book on table
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isometric contraction
a lot of tension, but no length change ( load exceeds muscle tension) holding book stead with outstretched arm
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how to make energy
- 1. creatine phosphate
- 2.anaerobic
- 3. aerobic
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creatine
helps to remove phospate head from ATP to make ADP which generates force, vice versa for 15 seconds
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anaerobic
no oxygen, glucose is catbolized to create 4 ATP with losing 2 ( glucose split into pyruvic acid) (30-40 sec)
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aerobic
oxygen, pyruvic acid goes into mitochondria to make ATP, carbon dioxide, water and heat
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fatigue
not enough calcium, creaitine, acetylcholine, etc
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slow oxidative
smallest, weakest type of skeletal fiber (dark red) a lot of mitochondria to use aerobic, ATP is split slowly, but high endurance
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