The Muscular System
B
ody-buildingandbody-sculpting
both build up muscles in selected
areas of the body, resulting in a gener-
ally pleasing shape or appearance.
Muscle makes up almost 40-50%
of the total mass of your body.
Many of these primary engines of
motion are intimately linked to
the skeletal system, but there
are many muscles that you don’t
even think about. For example,
smooth muscle tissue forms the walls
of your blood vessels, gastrointestinal
tract, and urinary bladder, helps control
blood pressure, circulate blood, move food through the
digestive tract, and receive and store urine for periods
of time. Your heart, made of cardiac muscle tissue,
works constantly throughout your life, without a rest.
Muscle is one of the few tissue types that you can
actually modify, but how? The answer is through rigor-
ous and regular exercise. You can change the size and
type of muscle fibers (cells), thereby increasing strength
and endurance. In fact, your muscle mass readily adjusts
to your lifestyle and exercise regimen. People with active
lifestyles tend to have more muscle mass than sedentary
individuals. Patients on long-term bed rest tend to lose
muscle mass quickly. Maintaining your muscle health is
important to maintaining your overall health.
Let’s take a closer look at these remarkable tissues.
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NATIONAL
GEOGRAPHIC
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