Transcript The Muscular System

Chap. 2 – The Muscular System
Skeletal Muscle
- Muscles that attached to bones
- Most prevalent
- VOLUNTARY – you make a
conscious decision to flex
- Striated
Smooth Muscle
Surround the body's internal
organs
 Contracts more slowly than
skeletal muscle but can remain
contracted for longer periods of
time
 INVOLUNTARY
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Cardiac Muscle
Only found in the heart
 INVOLUNTARY – autonomic
nervous system is responsible for
making the muscle fibers contract
 Muscle tissue is striated in
appearance like skeletal muscle
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To summarize...
The Neuromuscular
System
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Term referring to the link between the
muscular system and the nervous system
Before a muscle contracts, a message
needs to be sent from the brain
The neuromuscular junction is the point
where the message from the brain meets
the muscle
The Neuromuscular Junction
The Motor Unit
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Muscle twitch: a single nervous impulse and
the resulting contraction
Motor unit = the motor neuron, it's axon
(pathway) and the muscle fibres it stimulates
The All-or-None Principle

The principle that states that when a motor
unit is stimulated to contract, it will do so
to its fullest potential
 Example:
if a motor unit consists of 50
muscle fibres and they are stimulated to
contract, either all of the fibres will
contract or none of them
Some educational videos...and
a funny one...
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How muscles contract:
http://videos.howstuffworks.com/hsw/6100-the-cellmuscle-cells-video.htm
Beating heart:
http://www.youtube.com/watch?v=AZ4RnmNgEN0&fe
ature=related
Remember when we said that babies' bones weren't
solid when they were born? Watch this kid dance.... :)
http://www.youtube.com/watch?v=kmLi5Shj5ec&featur
e=related
Worksheet