Transcript MUSCULAR SYSTEM

About
Contractions, muscle
disorders, and the
effects of exercise
Types of contractions
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Isometric contractions- muscle does not shorten
& no movement occurs. Ex.- pushing against a
wall
Isotonic contractions - produces movement at a
joint such as walking, running or breathing
Twitch contractions- quick jerky contraction
Tetanic contractions – contractions which do not
relax
Atrophy
 Atrophy
is when muscles
shrink in mass from lack of
use.
 Why do you think this
occurs?
It’s not a bad thing…
 Muscular
hypertrophyincrease in muscle size
MUSCULAR DISORDERS
 Myo
– prefix that means
“muscle”
 Myalgia – muscle pain
 Myopathies – muscle
disorders
MUSCULAR DISORDERS
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Injury
• Strain – tearing or stretching fibers,
caused by overexertion or trauma
• A strain near a joint can be a SPRAIN
• Inflammation – myositis
• Crush injuries can release muscle
contents and cause kidney failure
• Stress can cause neck and back pain
MUSCULAR DISORDERS
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Infections
• Poliomyelitis was an infection of muscles that
caused paralysis and often death.
• The president Franklin Delano Roosevelt had
polio and spent most of his adult life in a
wheelchair.
• “Polio” was common in the early 20th century
has nearly been eliminated by a
comprehensive vaccination program.
MUSCULAR DISORDERS
 Muscular
Dystrophy
• A genetic disease
• Is actually a group of
disorders characterized by
muscle atrophy
• Is often fatal
MUSCULAR DISORDERS
 Multiple
Sclerosis
• An autoimmune disease
characterized by chronic
fatigue and weakness
Effects of exercise
Muscular hypertrophyincrease in muscle size
 Improved tone and
posture
 More efficient heart
and lung function
 Decreased fatigue
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Strength training
Increases the number
of microfilaments in
each fiber
 Increases muscle mass
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Endurance training
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Increases the muscles’
ability to sustain moderate
exercise over a long period
Also called “cardio” or
“aerobic” exercise
Does not usually result in
hypertrophy
More blood vessels develop to meet the need of
the muscles.
This increases efficiency of delivery of oxygen
and nutrients to muscles.