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THE MUSCULAR SYSTEM
Mrs. Neistadt Biology
THE MUSCULAR SYSTEM
MUSCULAR SYSTEM*There are 206
bones in the
body
* There are
approximately
640 skeletal
muscles in the
body.
*Three Types of Muscle
*Muscles are classified according to their structure and function.
*SMOOTH MUSCLE
*Involuntary Muscle
*Muscle of the internal organs:
(stomach, intestines, etc.)
*Not striated, or striped, 1
nucleus
*CARDIAC MUSCLE
*Involuntary
*Only in the heart
muscle
*Contracts efficiently
and rhythmically
*Striped or Striated,
with light and dark
bands and many nuclei
*SKELETAL MUSCLE
*Voluntary Muscle
*Attached to bones
by tendons
*When contracted,
cause the body to
move
Skeletal Muscle Contraction
*Most skeletal muscles are arranged in opposing, or antagonistic pairs.
Muscle Fibers
*TWO TYPES OF MUSCLE FIBERS:
Slow-
twitch
Fast-
twitch
*Slow-twitch muscle fibers
*Slow-twitch muscle fibers have more endurance than fast-twitch muscle fibers.
They contain myoglobin, a respiratory molecule that stores oxygen and serves as an oxygen reserve.
SLOW-TWITCH FIBERS
Fast-Twitch Muscle Fibers
*Fast-twitch muscle fibers fatigue easily but provide great strength for rapid, short movements.
They rely on anaerobic metabolism, which causes a buildup of lactic acid.
FAST-TWITCH FIBERS
ENERGY FOR MUSCLES
*Muscle cells need energy to contract
*Muscle cells use cellular respiration
to make ATP (adenosine
triphosphate)
* ATP = Energy (aerobic)
*If enough oxygen is not available,
muscles will rely on lactic acid
fermentation for energy. (anaerobic)
WHEN SOMETHING GOES WRONG…
Muscular Dystrophy-• An inherited disease that affects the skeletal muscles in the body.
• Eventually, the muscles are destroyed and the person may become paralyzed.
REVIEW QUESTIONS:W R I T E O N A S E PA R AT E PA P E R T O T U R N
I N:
1.Compare and Contrast skeletal, smooth and
cardiac muscle.
2.Explain why it is important for skeletal muscles
to be found antagonistic (opposite) pairs.
3.Explain why it is important that no muscle
contains only slow-twitch or only fast-twitch fibers.
4.When does a muscle require ATP?
5.Related to #4: Why does your body use energy
even when you are sleeping?
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