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36 Cards in this Set

  • Front
  • Back
epimysium
-layer of CT which ensheaths the entire muscle.
-Composed of dense irregular CT. It is continuous with fascia and other CT
Periosteum
specialized CT covering all bones
proximal
closer to trunk
distal
further from trunk
superior
closer to head
inferior
closer to feet
origin
proximal muscle attachment
insertion
away from center attachment
muscle fiber
long, cylindrical cells
fasiculi
- groups of up to 150 muscle fibers
- surrounded by CT perimysium
perimysium
CT that surrounds fasiculi
endomysium
-CT that surrounds each muscle fiber
continuos with sarcolemma
sarcolemma
muscle fiber's membrane
neuromuscular junction
junciton between a motor neuron and the muscle it innervates
motor unit
motor neuron + muscle fibers innervated by it
sarcoplasm
cytoplasm of a muscle fiber
myofibril
contain stuff that contract a muscle cell

-myosin and actin
myosin
-thick fiber - 16nm
-contain cross-bridges
actin
-thin filament - 6nm
-2 strands in a double helix
sarcomere
myosin and actin arranged longitudinally
M-bridge
-adjacent myosin filaments anchor at the M-bridge
-center of sarcomere
*center of H-zone
Z-line
-actin filaments are aligned at both ends of sarcomere

* anchored at the z-line
* repeated throughout the entire myofibril
A-band
dark, myosin filaments
I-bant
light, actin filament in ajacent sarcomeres
sarcoplasmic reticulum
-surrounding each myofibril
* run from z-line to z-line and terminates in vessicles, where Ca stored
T-tubules
un perpendicular to sarcoplasmic reticulum and terminate at the z-line between two vessicles
triad
t-tubule inbetween and perpendicular to 2 sarcoplasmic reticulum vessicles
action potential
electrical nerve impulse - arrive at all levels of muscle fiber because t-tubule runs continuously with sarcolemma and between outlying myofibrils
sliding filament theory phases
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
rest phase
* little calcium present in myofibril
* few myosin cross-bridges bound to actin
* no tension in muscle
excitation-contraction coupling phase
* 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
contraction phase
* 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
relaxation phase
* when stimulation of motor nerve stops
* Ca pumped back into sarc. retic.
concentric muscle action
* when total tension in all crossbridges of a muscle is great enough to overcome any resistance to shortening
isometric
* tension in the cross-bridges equals the resistance to shortening and the muscle length remains the same
eccentric
* tension in cross bridge is less than the external resistance and muscle lengthens despite contact between myosin c-b heads and actin filaments