The Muscular System
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Transcript The Muscular System
The Muscular System
Functions
Stabilize joints with their tendons
Produce movement
Produce heat to maintain body
temperature
muscle – an organ that can relax,
contract, and provide force to move
your body parts.
Muscle Types
Voluntary – muscles you can control
hand, arm, leg, face…
Involuntary – muscles you cannot
consciously control
Continuously work all day
heart, peristalsis, eyes…
Working Levers
The action of muscles, bones, and
joints working together is very similar
to a simple machine
Bones = rods
Joints = fulcrum
Muscle contraction/relaxation = force
3 Classes of Levers
1st class – the fulcrum lies between
the effort force and the load
2nd class – the load lies between the
fulcrum and the effort force
3rd class – the effort force is between
the fulcrum and the load
1st Class Lever
2nd Class Lever
3rd Class Lever
Skeletal Muscle
Muscles that move bone
Voluntary muscles that are striated
(striped)
Contract quickly and tire more easily
Tendons – thick bands of tissue that
connect bones to muscles
Ligaments connect bone to bone to
form a joint
Skeletal Muscle
Cardiac Muscle
Found only in the heart
Striated, involuntary
Contracts 70 times per minute
Smooth Muscle
Found in internal organs
Intestines, bladder, blood vessels…
Nonstriated, involuntary muscles that
slowly contract and relax
Working Muscles
Pairs of skeletal muscles work
together
When one muscle pair contracts, and the
other one relaxes, or returns to original
length
Muscles always pull, they never push
When muscles are used they increase
in size (and sometimes number)
However, when muscles are not used
they can shrink
Remember…
Muscles require energy to contract
and relax
Blood carries energy filled molecules
to your muscle cells, then the stored
chemical energy is released
When a muscle uses all of its energy,
it becomes tired, and blood supplies
more energy-rich molecules to your
muscles while they are at rest