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36 Cards in this Set
- Front
- Back
epimysium
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-layer of CT which ensheaths the entire muscle.
-Composed of dense irregular CT. It is continuous with fascia and other CT |
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Periosteum
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specialized CT covering all bones
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proximal
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closer to trunk
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distal
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further from trunk
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superior
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closer to head
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inferior
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closer to feet
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origin
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proximal muscle attachment
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insertion
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away from center attachment
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muscle fiber
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long, cylindrical cells
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fasiculi
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- groups of up to 150 muscle fibers
- surrounded by CT perimysium |
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perimysium
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CT that surrounds fasiculi
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endomysium
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-CT that surrounds each muscle fiber
continuos with sarcolemma |
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sarcolemma
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muscle fiber's membrane
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neuromuscular junction
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junciton between a motor neuron and the muscle it innervates
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motor unit
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motor neuron + muscle fibers innervated by it
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sarcoplasm
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cytoplasm of a muscle fiber
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myofibril
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contain stuff that contract a muscle cell
-myosin and actin |
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myosin
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-thick fiber - 16nm
-contain cross-bridges |
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actin
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-thin filament - 6nm
-2 strands in a double helix |
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sarcomere
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myosin and actin arranged longitudinally
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M-bridge
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-adjacent myosin filaments anchor at the M-bridge
-center of sarcomere *center of H-zone |
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Z-line
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-actin filaments are aligned at both ends of sarcomere
* anchored at the z-line * repeated throughout the entire myofibril |
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A-band
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dark, myosin filaments
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I-bant
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light, actin filament in ajacent sarcomeres
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sarcoplasmic reticulum
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-surrounding each myofibril
* run from z-line to z-line and terminates in vessicles, where Ca stored |
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T-tubules
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un perpendicular to sarcoplasmic reticulum and terminate at the z-line between two vessicles
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triad
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t-tubule inbetween and perpendicular to 2 sarcoplasmic reticulum vessicles
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action potential
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electrical nerve impulse - arrive at all levels of muscle fiber because t-tubule runs continuously with sarcolemma and between outlying myofibrils
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sliding filament theory phases
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resting, excitation-contraction coupling, contraction, recharge, relaxation
-actin filament slide inward on myosin filaments bringing the z-lines toward the center of the sarcomere... shortening the muscle fiber |
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rest phase
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* little calcium present in myofibril
* few myosin cross-bridges bound to actin * no tension in muscle |
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excitation-contraction coupling phase
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* B4 Cross-bridges can flex, mysoin must connect with actin
* when sacr. retic. releases Ca ions, it binds with troponin * causes a shift to happen in tropomyosin - runs along length of of actin filament * myson now attaches to actin |
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contraction phase
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* hydrolysis of ATP to ADP provides energy
- ATPase catalyses reaction * ATP molecule must replace ADP on mysocin c-b head for the head to detach from active actin and recock |
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relaxation phase
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* when stimulation of motor nerve stops
* Ca pumped back into sarc. retic. |
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concentric muscle action
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* when total tension in all crossbridges of a muscle is great enough to overcome any resistance to shortening
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isometric
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* tension in the cross-bridges equals the resistance to shortening and the muscle length remains the same
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eccentric
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* tension in cross bridge is less than the external resistance and muscle lengthens despite contact between myosin c-b heads and actin filaments
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