1. 17.2 The Skeletal System
Life Science, Ms. Wells

2. Functions of Skeletal System
Provides all movement
Works with Muscles
Skeletal System + Muscular System = Musculoskeletal System

3. Bone Shapes
Long Bone = in arms & legs
Short Bone
in feet & hands

4. Bones Shapes Irregular Bones = spinal column (vertebrae)
Flat Bones = ribs, skull

5. Bones are Connective Tissue!

6. Bone Types Compact Bone Spongy Bone Solid layer Outer layer
Very strong
Dense calcium network
Spongy Bone
Lightweight, STRONG
Full of holes (for blood vessels)
Middle layer

7. Calcium Network

8. Spongy Bone

9. Joints
Function: allow for movement or to create a seal between 2 bones
Definition: any place where 2 bones meet

10. Immovable Joints NO movement/motion Example: Skull
Bones in skull are fused together to seal brain inside

11. Slightly Movable Joints
Can “give” a little, more flexible
But usually don’t move much
Example: Ribs

12. Freely Movable Joints Bones glide back & forth past each other
Lots of motion
Many types
Hinge
Pivot
Ball and Socket

13. Freely Movable: PIVOT Joint
Motion: twist a door knob
Example: wrist

14. Freely Movable: HINGE Joint
Motion: open and close only one way
Example: knee, elbow

15. Freely Movable: BALL AND SOCKET
Motion: throwing a baseball
Example: shoulder, thigh bone to hips

16. Ligaments Connective tissue that holds bones together @ joints
Stretchy

17. Osteoporosis Osteo- = bone -porosis = break down, porous, holes
Loss of density in bone
Calcium network thins
Bones become brittle
Effects women more than men

18. “Soft Spot” or Fontanelle
Immovable skull joints are not entirely fused in infants
Easier to squeeze big head out of mother

19. Cartilage Bones missing the CALCIUM network! Flexible, soft
Example: ears, nose, lining of joints
All bones start out as cartilage
Add calcium to harden = OSSIFY

20. Cartilage & Joints Cushions joints so bones don’t grind
Arthritis = cartilage covering bones in joints wears down which causes pain and limits movement

21. THE END!