2. Movement
In the process of moving, energy is used, work is done.
More than 600 muscles in the body
Some muscles in your body are always moving.
Breathing
Heart beating
Digestive system working
3. Muscle control
Voluntary muscles—muscles you are able to control
Examples: face, hand ,arm
Involuntary muscles—muscles that you can’t control
Work all day long, all your life
Pump blood through vessels and move food through digestive
system
4. Classification of Muscle Tissue
Skeletal muscle tissue
Voluntary muscles that move bone
More common than other muscle types
Attached to bones by tendons
Striated (appear striped under microscope)
5. Cardiac muscle tissue
Found only in heart
Striated
Contracts about 70 times per minute all your life
Smooth muscle tissue
Non-striated
Involuntary
Found in bladder, intestines, blood vessels, other
internal organs
6. Working Muscles
You move because pairs of skeletal muscles work
together.
When one muscle of a pair of muscles contracts, the
other muscle relaxes or returns to its original length.
Muscles always pull; they never push
7. Changes in Muscles
Over time, muscles become larger or smaller depending
on whether or not they are used.
Muscles that are given regular exercise respond quickly
to stimuli.
Some of the change in muscle size is because of an
increase in the number of muscle cells.
8. However, most of the change in muscle size is because
individual muscle cells become larger.
Muscles that aren’t worked, become smaller in size.
9. How muscles move
Muscles need energy to contract and relax.
Your blood carries energy-rich molecules to your
muscle cells, where chemical energy is released.
As muscle contracts, this released energy changes to
mechanical energy (movement) and thermal energy
(heat).
