Download The Muscular System

Muscular
System
How do muscles work?
• Muscles can't push. They pull.
• Muscles often work in pairs so that they can
pull in different or opposite directions, like a
finger that moves in different directions.
Muscular System:
Involuntary/Voluntary
• The muscular system moves the body.
• The body has over 600 muscles.
• Some muscles are called voluntary, that means that
you choose to use them. How active you are
depends on how much use they get!
• Some muscles are called involuntary because they
work without you thinking about them. These are
muscles like the heart and digestive system.
• Ligaments are strong connective tissue that attaches
muscle to bone.
Function of Muscles
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Produce movement
Maintain posture
Stabilize joints
Generate heat
The Muscular System
Muscles are responsible for
all types of body movement
Three basic muscle types are
found in the body
Skeletal muscle
Cardiac muscle
Smooth muscle
Skeletal Muscle Characteristics
• Most are
attached by
tendons to
bones.
Skeletal Muscle Characteristics
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Cells are multinucleate
Striated – have visible banding
Voluntary – subject to conscious control
Cells are surrounded and bundled by connective
tissue
Cardiac Muscle Characteristics
• Has striations
• Usually has a single
nucleus
• Joined to another
muscle cell at an
intercalated disc
• Involuntary
• Found only in the
heart
Smooth Muscle Characteristics
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Has no striations
Spindle-shaped cells
Single nucleus
Involuntary – no
conscious control
• Found mainly in the
walls of hollow organs
Comparison of Types of Muscle
- The Muscular System
Muscles at Work
• Because muscle cells can only contract, not
extend, skeletal muscles must work in pairs.
While one muscle contracts, the other muscle
in the pair relaxes to its original length.
Effects of Exercise on Muscle
Aerobics result in stronger muscles due to
increase blood supply
Muscle fibers increase mitochondria and
oxygen storage
Muscle becomes more fatigue
resistant
Heart enlarges to pump
more blood to body
Does not increase skeletal
muscle size
Effects of Exercise on Muscle
• Results of increased muscle
use from resistance
training
• Individual muscle cells
make more contractile
filaments & connective
tissue increases
– Increase in muscle size
– Increase in muscle strength