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Muscular System (Body Movement (Extension (Movement that increase angle of…
Muscular System
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Sliding Filament Theory
- Myosin attaches to actin, forming actin, myosin crossbridges
- Myosin head moves toward M line of sarcomere, pulling actin filaments past myosin
- Ca++ binds to actin myofilament, exposing the myosin binding site
- This action is repeated many times powered by ATP
- Nerve impulse or action potential travels down sarcolemma & into tubules, causing sarcoplasmic reticulum to release Ca++ into sarcoplasm
- Z lines get closer together as actin & myosin filaments slide past each other, & sarcomeres shorten (H zone disappears), shortening the entire myofibril
Muscle Contraction
- Ach diffuses across synaptic cleft, & binds with receptors on motor end plate of the muscle cell
- This causes receptor to change shape, & opens Na+ channels in sarcolemma
- Nerve impulse reaches synaptic end bulbs & causes synaptic vesicles to fuse with neurolemma & release Ach
- Electrical current is generated & is carried along sarcolemma, cause action potential (muscle contraction)
Anterior Muscles
Head/Neck Muscles
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Sternocleidomatoid
Flexes neck, rotates head
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Hip/Thigh/Leg Muscles
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Quadriceps group
Vastus medialis, intermedius, and lateralis, & the rectus femoris
All extends knee, rectus femurs also flex hip on thigh
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Types of Muscle Tissue
Cardiac
cells are long, cylindrical, branched, has single central nucleus
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Skeletal
Cells are long, cylindrical, parallel, & multi-nucleated
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Posterior Muscle
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Hip/Thigh/Leg muscles
Hamstring Muscles
Semitendnosus, semimembranosus, bicep femoris
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