1. The Skeletal System

2. Five Major Functions Gives shape and support to body
Protects your internal organs
Ex: ribs protect heart, skull protects brain
Major muscles are attached to bone and help them move
Blood cells formed in center of bones in soft tissue called red marrow
Major quantities of calcium and phosphorus compounds are stored

3. Bone structure Bones can have different sizes, shapes,
Bone surface covered with periosteum
Small blood vessels in periosteum carry nutrients to bone
Two different bone tissues
Compact bone
Spongy bone

4. Compact Bone Directly under periosteum
Hard, strong layer that gives bones strength
Framework containing calcium phosphate
Living tissue of bone cells and blood vessels that keeps bones from being too rigid, brittle, or easily broken

5. Spongy Bone Located towards end of long bones
Has many small, open spaces that make bones lightweight
Inside cavities and spaces in spongy bones, substance called marrow
Some marrow yellow and composed of fat cells
Red marrow produces red blood cells

7. Cartilage
Smooth, slippery, thick layer of tissue that covers the end of bones
No blood vessels or minerals
Flexible and important in joints because it acts as shock absorber
Makes movement easier by reducing friction

8. Bone Formation Before being born, baby skeleton made of cartilage
Bone cells called osteoblasts deposit calcium and phosphorus in bones, making the tissue hard
At birth, we have >300 bones, but as we develop, bones fuse and only have 206
Bone tissue always being formed
Osteoblasts build bone
Osteoclast breaks down bone

9. Joints Any place where two or more bones come together
Bones kept far enough apart by cartilage
Classified as immovable or movable
Ligaments tough band of tissue that holds bones in place at joints

10. Immovable joints Allows little or no movement
Joints of skull and pelvis are immovable

11. Movable Joints All movement requires movable joints Several types
Pivot
Ball and socket
Hinge
gliding

12. Pivot Joint
One bone rotates in a ring of another bone that does not move
Ex: turning your head

13. Ball and Socket
Bone with rounded end that fits into a cuplike cavity on another bone
Provides wider range of motion
Why your arms and legs can swing in almost any direction

14. Hinge Back and forth movement like hinges on door
Ex: elbows, knees, fingers

15. Gliding Joint One part of a bone slides over another bone
Move in back and forth motion and are used most in body
Ex: wrist, ankle

16. Joint Problems Arthritis pain, stiffness, and swelling of joints
Osteoarthritis results when cartilage breaks down because of years of use
Rheumatoid arthritis ongoing condition in which the body’s immune system tries to destroy its own tissues