Functions of skeletal system

• Support
• Storage of Mineral and Lipids
• Blood Cell Production
• Protection
• Leverage

Sutural Bones

• Wormian bones - small, flat, irregular bones of the skull.

Irregualr bones

• Short, flat, notched or ridged surface.
• Spinal vertebrae, bones of pelvis, some skull

Short Bones

• small and boxy
• carpal(wrists)
• tarsal(ankles)

Flat Bones

• Thin, parallel surfaces.
• Roof of skull, sternum, ribs, scapulae.
• Provide protection for underlying tissues
• Provide surface area for attchment of skeletal muscles. 

Long Bones

• Long,slender
• Arm, forearm, thigh, leg, palms, soles, fingers, toes
• The femur, largest and heaviest.

Sesamoid Bones

• Sesame see shape, small, flat
• Inside tendons, located near joints
• Knees, hands, feet.   

Spongy Bone

• Network of struts and plates(latticework)with a thin covering, or cortex of compact bone. 
• Superficial layer covering spongy bone is cortical bone. 

Accounts for 2/3 of weight of bone.

• Calcium phosphate .

Name the 4 types of cells Bones contain.

• Osteocytes
• Osteoblasts
• Osteoprogenitor Cells
• Osteoclasts 

Osteocytes

• Mature bone that makes up most of the cell population.
• Maintain the protein and mineral content of the surrounding matrix.
• Partcipate in the repair of damaged bone. 

Osteroblatsts

• Produce new bone matrix(ossification/osteogenesis).
• Make and relase proteins and other organic components of the matrix(osteoid).
•  Assists in elevating local concentrations of calium phosphate above its solubility limit, triggering deposit of calcium salts within the matrix.
• Thus converting osteoid into bone.

Osteoprogenitor

• Mesenchymal cells
• Maintain populations of osteroblasts
• Important in repair
• Located in the inner, cellular layer(edosteum) that lines the passageways containing blood vessels that penetrate the matrix of compact bone.

Osteoclasts

• Cells that remove and reclyle bone matrix.
• Large cells that contain 50 or more nuclei.
• Derived from stem cells that produce macrophages.
• Acids and proteolytic enzymes secreted by osteoclasts dissolve matrix and release stored minerals.(osteolysis), or resorption, important regulation of calcium and phosphate concentrations in body fluids.

Intramembranous Ossification

• Begins when osteoblasts differentiate within a mesenchymal or fibrous connective tissue.
• Also called dermal ossification because it usually occurs within the dermal layer.   

Osseous tissue if highly ______

• Vascular

3 sets of Blood Vessels develop:

• Nutrient Artery and Vein-supply diaphysis form by invading the cartilage as endochondral ossification begins.
•  Metaphyseal Vessels- supply blood to inner surface of each epiphyseal cartilage, where that cartilage is being replaced by bone.
• Periosteal Vessels- Blood vessels from the periosteum provide blood to the superfial osteons of the shaft.

A crack or break in a bone is called a

• Fracture

Repair of a fracture involves what?

• Formation of a fracutre hematoma
• External callus
• Internal callus 

______ Has a widespread effect on aging skeletal tissue.

• Osteopenia

Bone forms through____ and enlarges through___ growth and remodeling.

• Ossification; appositional 

_____ Plays a critical rold in bone physiology.

• Calcium

Spongy bone contains____ typically in an open network.

• Trabeclae

A disorder of bone growth that causes the most common type of dwarfism.

• Achondroplasia

Inadequate ossification

• Osteopenia-begins between ages 30-40.(aging)
• Osteoblasts activity begins to decline, while osteoclast activity continues at previous levels.