1. Skeletal System

2.  Bones and cartilage  Alive and active  206 bones in humans  Support and protection  Helps maintaining homeostasis  Store minerals, make blood cells

3.  Functions of bones 1. Protect organs (ribs protect heart and lungs) 2. Store minerals 3. Role in movement 4. Bone marrow (making blood cells)

5.  Bone is a living organ made up of different types of tissues 1. Connective tissue and minerals 2. Osteoblast cells – mineral deposition 3. Spongy bone – open spaces in bone 4. Compact bone – no visible open spaces  Bone marrow – two types 1. Red marrow – red and white blood cells synthesis 2. Yellow marrow – stores fats

7.  During development most bones are soft  Bone formation initiates as flexible tissue - cartilage  As development occurs cartilage is replaced by bone  During growth, bones also increase in size  During childhood, most bones still have growth plates of cartilage  These growth plates provide a place for bones to continue to grow

8.  A place where two or more bones meet is called a joint  Some joints, such as fixed joints, allow little or no movement  Many of the joints in the skull are fixed joints  Other joints, such as your shoulder, allow a lot of movement  Joints can be classified based on how the bones in a joint move 1. Gliding or sliding joints 2. Hinge joints 3. Ball and socket joints

10.  Joints are often placed under a great deal of stress  But they can withstand a lot of wear and tear because of their structure  Joints are held together by ligaments  Ligaments are strong elastic bands of connective tissue  They connect the bones in a joint  Also, cartilage covers the ends of many bones. Cartilage helps cushion the area in a joint where bones meet.

11. 1. Fracture 2. Dislocation of joint 3. Sprain – ligament stretched or torn 4. Osteoporosis  Bone density decreases  Bones become weak 5. Arthritis - joints may swell or stiffen 6. Gout – accumulation of uric acid 7. Nutrition and bone heath