1. Muscular System

3. Function
The main function of the muscular system is to help provide movement for the body

4. Why are muscles important?
Every time you move you use a muscle.
Muscles keep your heart beating. 
Muscles keep your lungs breathing. 
Muscles also help keep you moving.  
Muscles can only perform ONE action…they can contract!

5. Muscle Work “Contract is the opposite of extend!”
When a muscle contracts, it makes itself shorter(it bunches up). 
When a muscle is not contracting, it is relaxed.
Muscles work in pairs- when one muscle contracts, the other muscle relaxes.
(Example: Using your bicep and tricep muscles)

6. Kinds of Muscles

7. Skeletal Muscle
Skeletal muscles – move your bones, biceps are an example.
They are VOLUNTARY muscles. They operate when your brain tells them to.  
A tendon is the strong connective tissue that connects muscle to bone.

8. Smooth Muscles
Smooth muscles – in charge of movements inside your body like pumping food around in your stomach or squeezing blood into blood vessels.
They are involuntary muscles. This means you do not consciously control them (you do not have to think about moving them- they just do it on their own).

9. Cardiac Muscles Cardiac muscles – strong muscles in your heart.
Cardiac muscles are also INVOLUNTARY muscles (thank goodness!)

10. Kinds of Muscles

11. Muscle Action
A muscle has many fibers (or pieces). Each fiber can contract. The more power you need, the more fibers that contract.
When muscle fibers contract for a long time (like when you run), they get tired. You breath fast to get more oxygen. Your heart starts to beat more quickly to get more blood to your muscles. The blood brings oxygen and glucose.

12. Bicep
Sterno Mastroid
Trapezius
Deltoid
Tricep
Pectoralis major
Latissimus Dorsi
Gluteus Maximus
Hamstring
Quadricep
Gastrocnemius
Achilles Tendon