Download Muscular System - Georgetown ISD

Muscular System
How do muscles work?
• Grip a clothespin with the thumb and index
finger of your writing hand. Squeeze the
clothespin open and shut as fast as you can for
20 seconds. Count how many times you can
squeeze the clothespin before your muscles tire.
• Rest for one minute. Then repeat.
• What happened? What were the differences?
Why do you think this is?
• Two kinds of muscles:
– Voluntary – those under your
own control
• Examples:
– Involuntary – not under your
own control, function on their
own
• Examples:
Three types of muscles
• Skeletal
– Function: movement due to muscles attached to
bones with a tendon; muscles work in pairs, one
muscle contracts or shortens and the other relaxes
– Voluntary
– Striated
– Examples: Biceps
and Triceps
Three types of muscles (cont.)
• Smooth
– Function: Lines the insides of organs to
automatically control their movements
– Involuntary
– Un-striated
– Examples: Intestines,
and Stomach
Three types of muscles (cont.)
• Cardiac
– Function: lines the heart; “pacemaker” cells
control contractions; cardiac muscle never gets
tired
– Involuntary
– Striated
– Examples: Heart