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