PEP 294: Lecture Notes

IV. Bone

1. Mechanical Functions of Bone (p. 90)

- provides a rigid skeletal framework -- supports and protects other body tissues

- forms a system of rigid levers -- can be moved by the forces from the attaching muscles

2. Material Constituents (p. 91)

- source of stiffness & compressive strength

- aging causes decrease in collagen and, as a result, increase in fragility

3. Types (pp. 94-96)

- protect underlying organs & soft tissues

- provide attachments (scapula, sternum, ribs, patella & skull)

 

- irregular shape: vertebrae, sacrum & coccyx

- specific functions -- spinal canal, attachment, weight bearing, etc.

 

- forms framework of appendicular skeleton -- clavicle, fibula, metacarpals, metatarsals, phalanges

- long cylindrical shaft & bulbous ends

- weight bearing -- tibia & femur

- mobility -- humerus, radius & ulna

- structure: body (diaphysis), marrow cavity, articular cartilage, etc.

4. Responses to Stress (p. 97-102)

"Bone elements place or displace themselves in the direction of functional forces."

- bone: alive & reacts to mechanical stress

- increase in functional force on the bone => increase in bone strength

- increase in functional force => increase in bone mass

- bone density: function of magnitude and direction of the mechanical stresses

 

- modeling: increase in bone mass

- remodeling: bone mass maintains w/ new bone cells

 

- hypertrophy: increase in bone mass

(a) in response to regular physical activity

(b) function of the intensity of the activity

(c) transfer effects

- atrophy:

(a) calcium loss

(b) decrease of bone mass, strength, and bone resistance