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