Download - Muscular System
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Muscular System
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Three Types
• Skeletal or striated – attached to bones, allows motion, voluntary control
• Smooth - work internal systems, involuntary i. e. digestive and circulatory
• Cardiac – heart muscle, involuntary
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Skeletal Muscle
• Works in pairs, one bends joint the other extends or straightens joint
• For full motion opposite muscle must relax while one flexes or contracts
• Muscle cells contract in response to nerves signals
• Contracting unit of a muscle – myofibril• Under voluntary control
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Myofibril
• Two types of proteins in contracting unit: myosin and actin
• Proteins slide over each other and overlap when contracted
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Skeletal Muscle cont.
• Two proteins (myosin and actin) give muscles a striped effect under a microscope – striated means banded or striped
• Two types of cells:– Red muscle cells – work longer– White muscle cells – work stronger
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Skeletal Muscle cont.
• Humans have muscles with both types of cells
• Exercise increases the size of your cells• Skeletal muscles have multiple nuclei
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Cardiac Muscle
• Found in the heart• Average adult heart rate – 60 – 100 bpm• Less striped than skeletal muscle• Have only one nucleus per cell• involuntary
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Smooth Muscle
• Short non-striped muscle cells• One nucleus per cell• Found in cell walls of veins, arteries,
digestive system, respiratory system etc.• involuntary
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Healthy Muscles
• Diet needs to include enough protein• Enough energy to fuel muscles• Strongest at about 25 years old
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Identifying Injuries
• X-Rays – form of energy that travels in waves
• Shows bones, good for detecting fractures• Goes through soft tissue but not bones• Bones show up as white areas• Need to be careful of exposure to X-Rays
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MRI
• Magnetic Resonance Imaging• Clear images of both bones and soft tissue• Magnetic energy causes atoms in your
body to vibrate (resonate). Computer analyzes vibration pattern to form image
• No evidence it cause any harm• Fairly expensive
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Muscles to Know