Muscular System
Nearly half our
weight comes
This is what
from muscle
happens without tissue.
muscles
There are 650
different muscles
in the human
body.
Muscles give us
“The power system” form and shape.
Muscles produce
most of our body
heat.

#One Main
Muscle Function
Responsible
for all body
movement.

#Two Main Muscle
Functions
 Responsible
for body form
and shape
(Posture)

#Three Main
Muscle Functions
 Responsible
for body heat
and
maintaining
body
temperature.
Test Your Gray Matter….

Muscles are responsible for producing
most of our : White blood cells,
Hormones, Protein synthesis, or Body
Heat.
Types of Muscles
Skeletal
Muscle
Smooth
Muscle
Cardiac
Muscle
Attached to
bone
Visceral
muscle
Found only
in the heart
Voluntary
Involuntary
Involuntary
Skeletal Muscles
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Attached to bone
Striated (striped)
appearance
Voluntary
Sarcolemma = cell
membrane
Contract quickly, fatigue
easily, can’t maintain
contraction for a long
period of time
Test your skeletal muscles…

Open and close your
dominant hand until
the teacher tells you
to stop.
Smooth Muscle
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Visceral (organ) muscle
Found in the walls of
digestive system, uterus,
and blood vessels
Cells small and spindle
shaped
Involuntary Controlled by
the autonomic nervous
system
Act slowly, do not tire
easily, can remain
contracted for a long time.
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Cardiac Muscle
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Found only in the
heart
Striated and
branched
Involuntary
Cells are fused when
one contracts, they
all contract
Test your gray matter..
Which of the following Which kind of muscle
muscles are
forms the walls of the
considered “voluntary” heart?
Striated,
cardiac, skeletal,
visceral
Cardiac, Skeletal,
Smooth, Visceral
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Sphincter
Special circular
muscles in openings
of esophagus and
stomach, and small
intestine, anus,
urethra and mouth
Skill
Working with skeletal muscles
Hand out worksheets for
group activity.

Characteristics of
Muscles
Contractibility
The ability of a muscle to
reduce the distance
between the parts of
its content or the
space it surrounds.
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Excitability
The ability to respond to
certain stimuli by
producing impulses.

Extensibility
The ability to be
stretched.

Elasticity
Ability of muscle to
return to its original
length when relaxing.
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Muscle Movement
How do we move?
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Muscle Movement
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Muscle move bones by
pulling on them.
As a muscle contracts, it
pulls the Insertion one
closer to the Origin bone.
Movement occurs at the
joint between the origin
and the insertion.
Rule: A muscle’s insertion
bone moves toward its
origin bone.
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Groups of muscles
usually contract to
produce a single
movement
A. Prime mover

muscle whose
contraction is mainly
responsible for
producing a given
movement
 B.
Antagonist
muscle whose actions
oppose the action of
prime mover in any
given movement.
 C.
Synergist

helps steady a
movement and
stabilize joint activity.

When the
antagonist
muscles contract,
they produce a
movement
opposite to that of
the prime movers.
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Motor Unit – a motor
neuron plus all the
muscle fibers it
stimulates.
Neuromuscular
Junction – the
junction between the
motor neuron’s fiber
which transmits the
impulse – and the
muscle cell
membrane.

Muscle chemical
neurotransmitter, diffuses
across the synaptic cleft
(carries impulse across
synaptic cleft)
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Acetylcholine
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Fatigue

caused by the
accumulation of lactic
acid in the muscles

Oxygen Debt

after exercise, the
amount of oxygen needed
by the muscle to change
lactic acid back to
glucose.
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MUSCLE TONE When muscles
are slightly
contracted and
ready to pull.
DIAPHRAGM –
Dome-shaped
muscle that
separates the
abdominal and
thoracic
cavities, aids in
breathing