anatomy exam 2
Chondrocytes
- mature cartilage cells, only cells in the cartilage matrix - Occupy lacunae - Avascular - they become part of the cartilage and enlarge it
Perichondrium
- separates cartilage from other tissues, contains blood vessels (provides nutrients/O2 for chondrocytes) - Outer fibrous region (dense CT) - The inner, cellular layer
Mesenchyme
- serves as the origin of all bone. - Bone growth occurs rapidly after birth, continues through adolescence and even until 25 years!
Epiphyseal Line
- Former location of epiphyseal plate; remains after epiphyseal growth has stopped - a bony structure that replaces the epiphyseal growth plate between 18 (females) and 21 (males) years of age - Closure accelerated in females by increasing levels of estrogen - Bone replaces all cartilage - Fractures between the epiphysis and the epiphyseal cartilage can permanently stop growth at this site
hyaline cartilage
- Most common type. - Tough and somewhat flexible - Reduces friction between bones - Found in synovial joints, rib tips, sternum, and trachea
7 step process: Cartilage to Bone
- Steps 1-4: Development of a primary ossification center inside the cartilage model - Steps 5-7: Increasing the length of a developing long bone and the creation of a secondary ossification center, formation of articular cartilage and epiphyseal plate
Epiphyseal closure
Epiphyseal plate gets narrower until it disappears
Calcification
The deposition of calcium salts within a tissue
Bone deposition
addition of minerals and collagen fibers to bone by osteoblasts
intramembranous ossification
bone develops directly from mesenchyme (loosely organized embryonic CT) or fibrous CT (flat bones, mandible)
Mesenchyme - 6 weeks of embryonic development (after fertilization)
bony skeleton begins to form, made of cartilage
chondros
cartilage
Mesenchyme - 8+ wks gestation
cartilage is replaced by bone via endochondral or intramembranous ossification
Ossification (osteogenesis)
formation of bone
interstitial growth
growth in length
appositional growth
growth in width
Bone remodeling
ongoing replacement and recycling of the organic and mineral components of the bone matrix
endochondral ossification
process in which bone forms by replacing hyaline cartilage (long bones)
Bone resorption
removal of minerals and collagen fibers from bone by osteoclasts (releasing Ca2+ ions into the bloodstream)
cartilage model
the hyaline cartilage that takes the shape of the future bone during endochondral ossification
chondroblasts
when the cells of the inner layer of the perichondrium divide. - they are immature chondrocytes that produce cartilage matrix
