Chapter 10 The Muscular System PDF

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Notes with Professor Longwith ...

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Chapter 10 The Muscular System -Interactions of Skeletal Muscles in the Body -Muscles usually work in groups perform “group actions” -Muscles are usually arranged in antagonistic pairs *Flexor-extensor How Skeletal muscles produce movement -Muscles exert force on tendon that pull on bones -Muscles usually span a joint -Muscle contraction changes the angle or position of one bone relative to another -Origin -Insertion -Belly: Fleshy part of the muscle between tendon and muscle Interactions of Skeletal Muscles in the Body (Lab Manual) -Prime mover (agonist) -Antagonist: -Synergists: Assist Prime Mover -Fixators: Stabilize the origin of a prime mover Functional Roles of Skeletal Muscles -Group Actions: Most movements need several muscles working together *Finish on D2L *Lab Manual with naming muscles Arrangement of Fascicles -Parallel (Strap-like) -Fusiform (Spindle shaped) -Pennate (“Feather shaped”) -Bipennate-2 pennate -Multipennate-3-6 pennate -Convergent -Circular (Sphincters) -Range of Motion: Depends on length of muscles fibers; long fibers=large range of motion -Power: Depends on total number of muscle fibers; many fibers=great power Lever Systems and Leverage -Lever: A rigid rod that moves on some fixed point -Fulcrum: A fixed point -Resistance: *Force that opposes movement *Load or object (bone or tissue) to be moved -Effort:

*Force exerted to achieve a movement *Effort provided by muscles -Motion is produced when the effort exceeds the resistance (Isotonic contraction) -Leverage: The mechanical advantage gained by a lever -Power: Muscle tension farther from joint produces stronger contraction -Range of Motion: Muscle tension closer to joint produces greater range of motion Mechanical Advantage -Load is near fulcrum, effort is far away -Only a small effort is required to move an object -Allows a heavy object to be moved with small effort Mechanical disadvantage -Load is far from fulcrum, effort is near the fulcrum *Large effort is required to move the object *Allows object to be moved rapidly, a “speed lever” Lever Systems and Levarage -First class lever: Effort Fulcrum resistance -Second class lever: Fulcrum Resistance Effort -Third class lever: Fulcrum effort resistance...