Muscular System – System of tough tissues that work together with your skeletal system to make
your body move.
I)
How your muscular system works – all muscles contract and extend. They work
similar to levers and pulleys as in science class.
a. Contract or Flex – means to shorten a muscle or exert the power of the muscle.
b. Extend or Relax – means to lengthen a muscle or relax the muscle.
* When one muscle contracts, the opposite muscle must be extended.
Example: bicep is contracted, the tricep must be extended.
II)
3 Types of Muscles – all depends on the location and function of the muscle. First
you need to know what voluntary and involuntary means:
1. Voluntary – you can control use of the muscle
2. Involuntary – you cannot control use of the muscle. It works on it’s
own without you thinking about contracting it.
Type of Muscle
Smooth
Muscle
Cardiac
Muscle
Skeletal Muscle
Appearance
Smooth
Striated
Striated
Voluntary or
Involuntary
Involuntary
Involuntary
Voluntary
Function
Example
Moves bones. Skeletal
muscles work in pairs.
When one contracts, the
other relaxes.
Controls
Controls
movement of
contractions
internal
of the heart.
organs.
They are attached to
bone by bands of tissue
called tendons.
Stomach
Heart
Bicep, Tricep,
Quadriceps
III)
Part of the Skeletal Muscle – This is how we are going to break down a muscle
and see how it works. It will be confusing at first, but be patient, you will get it.
1. Myofibril – the smallest bundle of a skeletal muscle and is made up of actin and myosin
filaments.
a. Actin – Thin proteins
b. Myosin – Thick proteins
c. Sarcomere – Repeating patterns from z-line to z-line that shorten upon muscle
contraction
The
thick
and
thin
filaments are arranged in a end to end to form a sarcomere. The thick filaments
Crossbridge
are joined together at the M line, and the thin filaments are joined together at the Z line, but the
that extends
two kinds of filaments are not joined to each other.
off myosin
and attach
to actin.