Potential Bone Growth and Growth in Length of Long Bones ( PART 7)
Bones increase thickness through
appositional growth
Epiphyseal plate thins and is replaced by what
bone
At the end of adolescences the chondroblasts begin to what?
divide less often
Grow in lengthening the long bone occurs where?
epiphyseal plate
Epiphyseal plate closure occurs when?
epiphysis and diaphysis fuse
long bones grow lengthwise by
interstitial (longitudinal) growth of epiphyseal plate
Calcification
surrounding cartilage matrix calcifies -chondrocytes die and deteriorate
Five zones of epiphyseal plate
1. Zone of resting cartilage 2. Zone of proliferating cartilage 3. Zone of hypertrophic cartilage 4. Zone of calcified cartilage 5. Zone of ossification
ossification zone
Chondrocyte deterioration leaves long spicules of calcified cartilage at epiphysis-diaphysis junction Spicules eroded by osteoclasts Covered with new bone by osteoblasts Ultimately replaced with spongy bone
Proliferation (growth) zone
Area of cartilage on diaphysis side of epiphyseal plate that is rapidly dividing New cells formed move upward, pushing epiphysis away from diaphysis, causing lengthening
Resting (quiescent) zone
Area of cartilage on epiphyseal side of epiphyseal plate that is relatively inactive // inactive, resting
hypertrophic zone
Area with older chondrocytes closer to diaphysis Cartilage lacunae enlarge and erode, forming interconnecting spaces