Question
click below
click below
Question
Normal Size Small Size show me how
Bone Growth
of a long bone
Question | Answer |
---|---|
Longitudinal Growth | endochondral ossification at epiphyseal plates |
Zone of Reserve Cartilage | next to epiphysis; irregularly scattered small chondrocytes; chondrocytes here anchor the epiphyseal plate to the epiphysis |
Zone of Proliferating Cartilage | larger chondrocytes stacked like coins are seen; these chondrocytes undergo mitosis to make new chondrocytes causing expansion of the plate |
Zone of Hypertrophic Cartilage | even larger chondorcytes occur in columns; here chondrocytes mature |
Zone of Calcified Matrix | a few layers, mostly dead cells; osteoclasts break it down; osteoblasts from diphysis lay down bone with osteocytes trapped inside --the metaphysis is the region where calcified matrix is replaced by bone to form the epiphyseal line |
Lengthwise Growth | evidence is the epiphyseal line 16-18 years of life- 20-25 is when epiphyseal cartilage is replaced by bone |
Circumferential Bone Growth | intramembranous ossification; periosteal osteoblasts deposit new bone on the periosteal surface of the diaphysis; endosteal osteoclasts break down old bone (marrow cavity enlarges and minderal ions are released into the blood) |