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Human Systems
Muscular System
Muscular System
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Definition:
 All the muscles in your body
Muscles:
 Body tissue that can change shape &
length, causing movement
Muscular System
Muscular System
Muscles
Main Action
Deltoid
Raises your arm sideways at the
shoulder.
Biceps
Bends your arm at the elbow.
Abdominals (4 muscles)
Pull in the abdomen. Flex the spine so
you can bend forward.
Quadriceps (4 muscles)
Straighten the leg at the knee. Keep it
straight when you stand.
Pectoral
Raises your arm at the shoulder. Draws
it across your chest.
Latissimus Dorsi (lats)
Pulls your arm down at the shoulder.
Draws it behind your back.
Trapezius
Holds and rotates your shoulders. Moves
your head back and sideways.
Triceps
Straightens your arm at the elbow joint.
Gluteals (3 muscles)
Pull your leg back at the hip. Raise it
sideways at the hip.
Hamstrings (3 muscles)
Bend your leg at the knee.
Gastrocnemius
Straightens the ankle joint so you can
stand on your tiptoes.
Muscles - Structures
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Skeletal – move the bones of skeleton
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Athletic activity: arms, legs, abdomen,
chest & shoulders
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Bundles of fibers
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Striped – two proteins make up fibers
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Voluntary: muscles you can control
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Animal tissue you eat
Muscles - Structures
Muscles - Structures
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Cardiac – makes up heart
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Only body organ of this type
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Bundles of fibers
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Striped – two proteins make up fibers
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Tight weave of fibers
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Involuntary: muscles you can’t control
Muscles - Structures
Muscles - Structures
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Smooth – makes internal organs,
stomach, intestines & walls of blood
vessels
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Spindle-shaped
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Not striped
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Involuntary: muscles you can’t control
Muscles - Structures
Muscles - Function
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Brain sends messages for muscle to
move
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Voluntary: you think about movement
Involuntary: part of your brain programs
movement without your thinking about it
Muscles - Function
Muscles - Function
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Muscles change length and work in PAIRS
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Muscle shortens & thickens: contracting
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Muscle lengthens: relaxing
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Move bones by pulling: connected by tendon
– tough, fibrous tissue that connects muscle
to bone
Muscles - Function
Muscles Working
in Pairs