The roles of the skeleton
a. Bones protect organs → ex. Ribs protect heart and lungs
b. Bones support tissues and provide framework for the body
c. Bones provide levers which muscles pull to produce movement
d. Tissue in bones provide stored reserve of phosphorus and calcium which can be used when needed (stores nutrients)
e. Bone marrow produces red blood cells
Classification of Bones
a. Long Bones: found in arms and legs → shell with marrow cavity in the middle (only type with cavity)
b. Short Bones: found in wrist and ankle
c. Flat Bones: flat and thin, found in cranium, ribs and scapula
d. Irregular Bones: Odd-looking bones (ex. Vertebrae)
e. Sesamoid: small, flat bones wrapped within tendons that move over bony surfaces (ex. Knee cap)
f. Wormian: Small jig saw fragments found along sutures of skull
Bone Formation and Remodelling
a. Ossification (formation) forms from compact bone and cancellous bone
b. Compact bone (begins as cartilage): Osteoblasts discharge osteoid where minerals are deposited to form bone
c. Cancellous bone (begins as fibrous membranes): osteoblasts release osteoid into membrane which forms a sponge-like bundle of fibres and bone forms outward from the centres in the membrane
d. With age osteoclasts work at the same pace but osteoblasts slow down
Osteoporosis risk factors
- Being thin or small framed
- Family history
- Smoking
- Excessive alcohol
- Lack of calcium and vitamin D
- Physical inactivity
- Being postmenopausal or having an early menopause
- Abnormal absence of periods
- Using certain drugs over a long period of time
Osteoporosis preventative measures
- Physical activity (weight bearing)
- Good diet (lots of vitamin D and calcium)
- Healthy lifestyle (no smoking, excessive alcohol or drugs)
- Regular bone density resting and medication when appropriate
- Fractures
a. Stress Fracture: when muscles are too fatigued to absorb shock so impact is placed on bone → like a crack in glass
b. Simple Fracture: no separation, but a break or crack in bone (hairline fracture)
c. Compound Fracture: bone breaks into separate pieces
d. Comminuted fracture: bone shatters into many pieces
