1. SKELETAL SYSTEM

2. 5 Functions of the Skeletal System
Support/structure – upright posture
Movement – attachment for muscles of movement (skeletal muscles)
Protection – surrounds many organs
Mineral storage – mostly calcium, also - phosphorous, Na, K
Blood cell formation – produced by red marrow in some bones (hematopoiesis)

3. BONES= CONNECTIVIE TISSUE
-- very active, living , in constant state of fluctuation, not lifeless

4. Classification of Bones

5. LONG- long, longitudinal axes, expanded ends EX: forearm, thigh bone [femur]
SHORT- cubelike EX: bones of wrist, ankle [tarsal of ankle]
FLAT- platelike with broad surfaces
EX: ribs, scapula, skull [parietal bone of skull]
IRREGULAR- variety of shapes, connected to
other bones EX: facial bones, [vertabrae]
E. SESAMOID- small, nodular embedded in tendons EX: [patella]

6. Parts of a Bone Epiphysis – expanded ends of the bone
articulates (contacts) other bones
coated w/ a type of articular cartilage (hyaline cartilage)
Diaphysis – long central shaft, b/w the epiphyses
Periosteum – sheet of dense, connective tissue
covers bones except where artic cart. is present.
Many blood vessels, osteoblasts (bone cells)
Merges w/ tendons and ligaments
bone repair and growth

7. Medullary Cavity – hollow space in diaphysis
filled w/ yellow marrow (fat for energy storage; body has ability to change yellow marrowred marrow if needed).
interior is lined w/ a membrane called endosteum.

9. 2 Types of Bone Tissue
Compact bone – solid, strong, resistant to bending – make up the walls of diaphysys -- small amount covers outside of epiphyses Spongy (cancellous) bone – many, tiny, interconnecting plates of bone – mostly in epiphysys; small amount in the diaphysis. – contains small spaces filled w/ red marrow

12. MICROSCOPIC STRUCTURE
3 Types of Bone Cells
Osteoblasts – “youthful” bone cells
-- build bone tissue
-- secrete a large amount of mesenchyme (bone matrix), which hardens to become bone tissue
Osteocytes – “older”, mature bone cells
-- produce less mesenchyme
-- trapped in a chamber (lacunae)
Osteoclasts – have the job of crushing, or breaking down bone tissue

14. QUIZ TOMORROW !!