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MUSCULAR SYSTEM
Functions of the Muscular System
• Without muscles, nothing in your body would
work
• All body movements depend on muscles
• Pump blood throughout your body
• Move food through your digestive system
• Control the movement of air in and out of
your lungs
Muscle Facts
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There are over 600 muscles in the body
40% of your total weight is muscles
Eyelids are the busiest muscles in the body
The gluteus maximus is the largest muscle in
the body
• There are 30 facial muscles
How Muscles Work
• Muscles work by means of two
complementary-or opposing- actions
• These are contraction, the shortening of a
muscle, and extension, the stretching of a
muscle
• Muscle contraction is triggered by nerve
impulses
• Muscles are only able to contract or pull
• Lactic acid is a waste produced when muscles
contract
Structure of the Muscular System
• The basic unit of a muscle is muscle cell
• A muscle is composed of bundles of fibers and cells
• The major muscles in the body are made up of
hundreds of bundles
• A muscle fiber is made up of even smaller units called
myofibrils
• Each myofibril is in turn made up of microscopic
filaments called actin and myosin, proteins that control
muscle contraction.
• The two types of muscle fibers are slow and fast
Types of Muscles
• Your body has three basic types of muscle
tissue:
– Smooth muscle
– Skeletal muscle
– Cardiac Muscle
Smooth Muscles
• Are the type of muscle concerned with the
movements of internal organs
• Found in the intestines, the bronchi of the
lungs, the stomach, the bladder, and the walls
of the blood vessels
• Also called involuntary muscles because they
work without a person’s conscious control
Skeletal Muscles
• Are the striped, or striated, muscles attached to
bones that cause body movements
• Form the largest part of the body’s muscular
system
• More than 600 such muscles
• Are voluntary, under conscious control
• Two or more skeletal muscles may oppose each
other’s actions
• While one contracts, the other relaxes
• Classified according to the type of action each
muscle performs
• Muscles that close a joint are called flexors
• Muscles that open out a joint are called extensors
Cardiac Muscles
• A special type of striated tissue that forms the
walls of the heart
• Your heart is the most important muscle in
your body
• Its unique properties enable it to contract
rhythmically about 100,000 times a day to
pump blood throughout the body
• Involuntary muscle
Major Muscles
• Deltoids are the muscles in each shoulder,
which help you move your shoulders every
which way
• Pectoralis are found on each side of your
upper chest
• Abdominals
• Triceps are the large, three headed muscles
that form the back of the upper arm
• Biceps
Injury Related Muscular problems
• Muscle strain- a strain, or a “pulled muscle,” is a
tearing or stretching of muscle fibers as a result
of suddenly pulling them too far
• Muscle cramp is a sudden muscle contraction
causing severe pain
• Bruise is a discolored area under the skin caused
by leakage of blood after an injury
• Tendinitis is the inflammation of a tendon, usually
caused by overuse.
• Achilles is the strongest tendon in the body