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?