Normal Bone, Joint Histo, Congenital Disorders - Gupta Flashcards
At what decade does bone resorption start to exceed bone formation
4th decade
Bone primarily composed of what 2 components?
- Type 1 collagen (osteoid)
- Hydroxyapatite
Name the 3 cells found in bone?
Osteoblasts, Osteoclasts, Osteocytes
Hydroxyapatite (bone) is main storage of what ions?
Calcium (99%), Phosphorus (85%), Sodium and Magnesium (65%)
% = total of body storage
Osteoblast function?
synthesize bone
Osteoclast function?
Resorb bone
Osteocyte function?
maintain bone
What are howship lacunae?
Pits created by osteoclast activity, indicating bone is undergoing resorption
Osteoclasts are derived from the same stem cells that produce ____?
macrophages
RANK ligand is found on what cells?
Stromal cell/osteoblast
RANK is found on what cells
Osteoclasts precursors
If RANK-ligand and RANK bind, what occurs next?
Osteoclast precursor cells are stimulated to produce NF-kB, causing the osteoclast precursor to differentiate into a active osteoclast
In addition to RANK-ligand, what other stimulatory cytokine is present on osteoblasts? What is its function?
Macropahge colony stimulating factor (M-CSF), similar function as RANK-L/RANK binding, will stimulate NF-kB production by osteoclast
Osteoprotegerin binds with RANK or RANK-Ligand? What happens when it binds?
Osteoprotegerin (OPG) binds with RANK-ligand (on osteoblasts) preventing binding of RANK, thus inhibiting NF-kb production and osteoclast differentiation.
Epiphyseal plate made of what 3 components?
Periosteum, bone marrow, residual cartilage
What are the 2 types of ossification?
Enchondral, Membranous
Which type of ossification occurs at epiphyseal plates?
ANS: Enchondral
Membranous occurs in cranial bones and everywhere there is periosteum
Which type of ossification occurs through a cartilage intermediate step?
Enchondral
Membranous does not require cartilage intermediate step. Cells from the periosteum differentiate into osteoblasts and make bone
Which type of ossification is involved in fracture healing.
Trick question. Both are involved.
What are the 2 types of bone in terms of characteristics? Vague question. I know
Lamellar bone, Woven bone