 Shape and support  Protects internal organs  Movement  Blood cell formation (bone marrow)  Storage (calcium and phosphorous)

 Not smooth – bumps, edges, rough spots and holes cover bones  Shape is inherited but can change when attached muscles are used  Bone’s surface is covered with periosteum  Periosteum: tough, tight-fitting membrane that covers a bone’s surface  Contains blood vessels that transport nutrients

 There are two types of bone tissue. Can you name them?

 Hard, strong layer  Contains calcium phosphate deposits  Bone cells and blood vessels found here  Keeps bones from breaking easily  Makes up 80% of human skeleton

 Located toward the end of long bones  Has small, open spaces that make bones lightweight  Spaces in spongy bone and bone cavities are full of marrow

 2 types: red and yellow  Yellow marrow: made of fat cells  Red marrow: produces red blood cells (2-3 million cells per second!)

 Smooth, slippery, thick layer of tissue covering the ends of bones  Flexible tissue, acts as shock absorber in joints  Also found in nose and ears

 Before you are born, your skeleton is made of cartilage  Osteoblasts: bone-forming cells that deposit calcium and phosphorous in bones  Make bone tissue hard  At birth: 300+ bones  Now: 206 bones

 Osteoblast: builds up bone  Osteoclast: breaks down bone  Releases calcium and phosphorus into bloodstream, keeps body working as it should be

 Joint: any place where two or more bones come together  Thin layer of cartilage prevents them from rubbing together  Ligament : tough band of tissue that holds bones together

 Immovable joints: allows little or no movement  Skull  Pelvis  Movable joints: allow body to move  Ball-and-socket: bone with rounded end that fits in cup-like cavity of another bone  Pivot: one bone rotates around another bone  Hinge: allow back and forth motion like a door hinge  Gliding: one part of a bone slides over another bone

 Immovable: skull  Ball-and-socket: shoulder, hip  Pivot: forearm  Hinge: knee, elbow  Gliding: vertebrae, wrist, ankle

 Cartilage protects bones from rubbing against each other  Cartilage breaks down over time: osteoarthritis  Arthritis most elderly people experience  Rheumatoid arthritis: body’s immune system tries to destroy its own tissue  Can affect adults of all ages

 Change the lyrics of a popular song to tell why we need the skeletal system (can be done with a partner).  Draw and color a comic strip with at least 5 frames that shows the 5 major functions of the skeletal system.  Use common household objects (or things found in the classroom) to build a model of a bone in the human body that highlights the 5 main functions of the skeletal system. ** For each assignment, you will need to explain how it displays the 5 functions of the skeletal system