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Muscular System (SLIDING FILAMENT THEORY (Myosin head moves toward M line…
Muscular System
SLIDING FILAMENT THEORY
- Myosin head moves toward M line of sarcomere, pulling actin filaments past myosin
- Myosin attaches to actin, forming actin/myosin crossbridges
- This action repeated many times powered by ATP
- Z lines get closer together as actin and myosin filaments slide past each other, and sarcomeres shorten
- Ca++ binds to actin myofilament, exposing the myosin binding site
- Nerve impulse or actin potential travels down sarcolemma and into T-tubules, causing sarcoplasmic reticulum to release Ca++ into sarcoplasm
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MUSCLES
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HEAD
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Buccinator: compresses checks, whistling and sucking
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MUSCLE CONTRACTION STEPS
- This causes receptor to change shape, and opens Na+ channels in sarcolemma
- Electrical current is generated and is carried along sarcolemma, causes actin potential
- Ach diffuses across synaptic cleft, and binds with receptors on motor end plate of the muscle cell
1.Nerve impulse reaches synaptic end bulbs and causes synaptic vesicles to fuse with neurolemma and release Ach.
MUSCLE TISSUES
CARDIAC
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Cells are long, cylindrical, branched, has single central nucleus
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SMOOTH
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Found mainly in hollow walls of organs, and eyes
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SKELETAL
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Cells are long, cylindrical, parallel, and multi-nucleated