The Muscular System
Jan 18, 2016
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 controlhand, arm, leg, face…
Involuntary – muscles you cannot consciously controlContinuously work all day heart, peristalsis, eyes…
Working Levers
The action of muscles, bones, and joints working together is very similar to a simple machineBones = rodsJoints = fulcrumMuscle 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 boneVoluntary 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 heartStriated, involuntaryContracts 70 times per minute
Smooth Muscle
Found in internal organsIntestines, bladder, blood vessels…Nonstriated, involuntary muscles that
slowly contract and relax
Working MusclesPairs 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