Flashcards in Congenital and Acquired Disease of Bone Development Deck (55)
____ is bone that has not been mineralized
What are osteoprogenitor cells?
Pluripotential mesenchymal stem cells. Under CBFA-1 stimulation they can become osteoblasts. They can also become macrophages.
____ sense mechanical stress and regulate serum calcium and phosphorous
_____ mediates osteoclasts and have PTH receptors
Composition of osteoid
type 1 collagen, 90% of organic part
Role of osteoblasts
synthesize osteoid, initiate mineralization, become surrounded by matrix and become osteocytes, mediate osteoclast activity, have PTH receptors
_____ are incased in bone and communicate through canaliculi
Osteoclasts require what cytokines for differentiation?
IL1,3,6,11, GM-CSF, M-CSF
Where do osteoclasts reside?
resorption pits, howship lacunae
____ are multinucleated cells responsible for resorption and remodeling.
What pararcine signals allow precursor cells to produce functional osteoclasts?
Osteoblast/ stromal cell membrane-associated RANK ligand (RANKL) binds to its receptor RANK located on the cell surface of osteoclast precursors. This interaction in the background of macrophage colony-stimulating factor (M-CSF) causes the precursor cells to produce functional osteoclasts
what does osteoprotegerin do?
Stromal cells also secrete osteoprotegerin (OPG) which acts as a decoy receptor for RANKL, preventing it from binding the RANK receptor on osteoclast precursors. Consequently OPG prevents bone resorption by inhibiting osteoclast differentiation
_____ is the cartilage between ossification centers.
Growth plate is in which part of the bone?
Why are children more prone to osteomyelitis?
richer blood supply
Describe the blood supply in growing bone vs mature bone
Growing: blood is supplied to growth plate in epiphysis.In mature bone, metaphyseal vessels penetrate the cartilage plate
OI is a family of diseases having in common mutations in _____.
type 1 collagen genes
What are the classic subtypes of OI
1- too litte pro-a1 made. 2-Pro-a1 is too short (lethal in urtero. 3) triple helix doesnt form well. 4) pro-a2 is too short
OI mode of inheritance
most are AD; 2 is either recessive or new AD
What are the 4 major clinical criteria of OI?
osteoporosis, blue sclerae, dintinenesis imperfecta, premature otosclerosis
Is OI the only thing you see blue sclera with?
No- things like ehlers danlos and rarely anemia, RA, and myasthenia gravis
What are the 2 clinical types of OI?
congenital and tarda
_____ is the most common cause of inherited dwarfism and is AD.
What causes achondroplasia?
reduction in chondrocytes at growth plate,
What is the specific mutation associated with achondroplasia?
receptor for fibroblast growth factor 3
What do limbs look like with achondroplasia?
short extremities with abnormally wide ends. normal trunk, large head with large forehead, deep set nose, prominent supraorbital ridges
What is a danger to life with achondroplasia?
deformity at the foramen magnum where minor trauma can cause compression of brain stem.
_____ is a known risk factor for new mutations with achondroplasia.
advanced paternal age
What do xrays of osteopetrosis show?
long bones without medullary cavities and misshapen, bulbous ends. Diffusely sclerotic.