Human Skeletal System

organic component

primarily non-cellular, made up of type 1 collagen, helps determine structure of bone, mechanical properties

type 1 collagen

ubiquitous protein, fairly rigid and linear, creates a fibril

fibril

form a collagen fiber when grouped together, serve as major structural component to bone matrix

inorganic component

calcium phosphate principle component, impurities can alter the physical properties of mineral crystals, affect function of bone tissue

osteoblasts

bone forming cells, on surface of bones: endosteum & periosteum, produce type 1 collagen

osteocytes

once osteoblasts, have extensive projections to establish and maintain communication with other cells, located in lacunae

osteoclasts

resorptive cells, bind to bone surface using attachment proteins, lower the pH of the local environment

woven bone

immature bone, many cells per unit volume, has isotropic mechanical properties

isotropic mechanical properties

mechanical behavior is similar regardless of the orientation of the applies forces

lamellar bone

mature bone, replaces woven bone, organized tissue with fewer cells per unit volume, anisotropic mechanical properties, main organizational structure is the haversian system, referred to as an osteon

anisotropic mechanical properties

mechanical behavior differs depending on the orientation of the applied forces, with its greatest strength parallel to the longitudinal axis of the collagen fibers

cortical bone

compact or dense, found in the shafts of long bones and enveloping most all other bones, found in areas subjected to predictable bending and torsional forces

trabecular bone

cancellous or spongy, found at ends of long bones and in cuboid bones, creates spicules to form 3-d branching lattice patterns, spicules form along areas of complex stress