The Skeletal System

there are 206 bones in the human body.

there are 27 bones in your hands and 26 bones in your foot.

there are 33 vertebrae.

there are 12 pairs of ribs (24 ribs).

there are 22 bones in the human skull.

there are more than 300 bones in the baby body that eventually fuse (grow together) to form adult 206 bones.

The Muscular System

SC.6.L.14.5

There are about 700 named muscles in the human body 

The primary purpose of the muscular system is to provide movement for the whole body.

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Muscles receive their ability to move 

through the Nervous System

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 5 major properties of the Muscular System:

1. Muscles can excite. muscles are able to receive and respond to stimulation.
2. Muscles can contract. after they receive stimulation, muscles contract (or shorten). remember contract means shorten. 
3. Muscles can Stretch. muscles can be stretched without damage.
4. Muscles are elastic. muscles are able to return to their original shape and length.
5. Muscles can adapt. with ↑or  ↓ work muscles can↑(hypertrophy) or ↓(hypotrophy) in size. 

 involuntary muscles                              

⇩                                                 

muscles you cannot control                                  

                                   ⇩                                           

                  digesting.                    

                 beating heart                    

                   breathing                     

  voluntary muscles

       ⇩

muscles you can control

       ⇩

running

smiling

walking

the prefix "IN" means "NOT"

the word "voluntary" comes from Latin and means "free will"

what happens to your PUPILs when they are in LOW LIGHT? 

They DILATE

(involuntarily)

what happens to your PUPILs when IT'S BRIGHT OUTSIDE? 

They CONSTRICT

(involuntarily)

3 TYPES OF MUSCLES

      ⇩                      ⇩                        ⇩

SMOOTH            SKELETAL         CARDIAC

involuntary                    voluntary                     involuntary

not striated                    striated                       striated

tires slowly                    tires easily                  never tired

contract                          contract                     only in heart

                                attached to bones             contract

how do skeletal muscles work?

skeletal muscles work in pairs.

when one muscle contracts, the other relaxes.

if you bent your arm at the elbow, the inside muscle biceps contracts, the outside muscle triceps relaxes. 

HOW TO KEEP YOUR MUSCLES HEALTHY?

!!!!  EXERCISE REGULARLY !!!!!