A 12 Bone Develop Flashcards
Why is bone resorbed?
- Minimize weight
- Mineral reserve
3 triggers of bone mineralization are?
- Alkaline phosphatase breaks down inhibitors
- Ca+ Pi product increases
- Nucleation sites
What are 3 facilitators of mineralization?
- Osteonectin (binds Ca+ and collagen I to mediate hydroxyapatite deposition)
-TGF-B induces collagen and alkaline phosphatase expression) - Hormones (estrogens, androgens, calcitonin) that increase osteoblastic activity.
Osteoclasts secrete what two substances for their function?
- Organic acids
- Hydrolytic enzymes
3 ingredients for endomembranous formation?
- osteoblasts
- Capillaries
- Matrix (from osteoblasts) calcifies
Between bone and cartilage, which one has blasts and cytes that continue dividing to some extent?
Cartilage
Between cartilage and bone, which grows both interstitially and appositionally?
cartilage. Bone is only appositional.
Primary and secondary growth centers are separated by?
Epiphyseal (growth) plate
Metaphysis is characterized/defined by what?
-Where ossification is occurring. (just “below” the epiphyseal plate)
What 4 zones are present in epiphyseal plate?
- Resting
- Proliferating
- Hypertrophy
- calcification
- ossification
What are the 3 locations of endochondral bone deposition?
- Periphery of bone epiphysis
- Metaphysis
- Under periosteum in diaphysis
what 3 types of cells can originate from osteoprogenitor cells?
fat, osteoblast, and chondroblasts.
all immature bone is considered compact/cancellous?
cancellous AKA spongy AKA trabeculated.
what is osteoid?
secreted matrix of a osteoblast that has not yet been mineralized.
what is the main component of osteoid?
Type 1 collagen (90% of organic)
osteoclast are stimulated by?
parathyroid hormone
thyroxine
inactivity
when does intramembranous ossification begin?
what does it form?
- onset= end of second month of gestation
- typical for the formation of flat bones without the per-cartilage model.
immature reticular (woven bone is replaced by what?
mature lamellar bone
tables = compact bone?
__________=spongy bone?
diploe
which type of bones are formed by endochondrial ossification?
long bones and irregular bones.
where does the earliest growth in a long bone occur?
at the perichondrium ( the perichondrium is the layer of dense CT that surrounds the cartilage of the developing bone)
testosterone and estrogen have what affect of the growth plate of the bone?
testosterone and estrogen accelerate the process of growth plate fusion/decreased lengthening.
endochondral ossification causes the bone to grow in___________? while appositional ossification causes the bone to grow in_________?
endochondral=length
intramembranous=width
where do the first ossification centers occur?
clavicle, arms, and mandible
what is/are rickets?
rickets is disorder caused by a lack of vitamin D, calcium, or phosphate. It causes weakness in the bones due to poor mineralization and leads to skeletal deformities.
what is osteomalacia?
“adult rickets”lack of vitamin D, calcium, or phosphate.
what is scurvy?
a vitamin C deficiency that causes decreased type 1 collagen production and weak bones.
what is achondroplasia?
Caused by normal appositional growth and impaired longitudinal growth because of faulty growth plates.
