18.1 - Skeletal system Flashcards
achondroplasia is due to impaired cartilage proliferation in the _______________
growth plate
achondroplasia is due to a mutation of what gene? what type of mutation is it?
- FGFR3
- activating mutation
what is the inheritance of achondroplasia?
AD
is achondroplasia a defect in endochondral or intramembranous bone formation?
endochondral
what is the inheritance of osteogenesis imperfecta?
AD
osteogenesis imperfecta is a defect in type ____ collagen synthesis
1
why are blue sclerae seen in osteogenesis imperfecta?
thinning of scleral collagen reveals underlying choroidal veins
osteopetrosis is due to poor function of what cell type?
osteoclast
what is the most common gene mutation variant leading to osteopetrosis? what is the result?
carbonic anhydrase II - loss of acidic microenvironment required for bone resorption
what are the hematologic manifestations of osteopetrosis? what is the mechanism?
- anemia
- thrombocytopenia
- leukopenia
- extramedullary hematopoiesis
- due to bony replacement of marrow (myelophthisic process)
what is the treatment for osteopetrosis?
bone marrow transplant
rickets / osteomalacia is due to what process?
defective mineralization of osteoid
- pigeon breast deformity
- frontal bossing
- rachitic rosary
- bowing of the legs
rickets
what are the serum levels of
- calcium
- phosphate
- PTH
- alk phos
in osteomalacia?
- low calcium
- low phosphate
- high PTH
- high alk phos
when osteoblasts are activated, what does that do to alk phos levels?
increase
osteoporosis is a reduction in bone mass of what type of bone?
trabecular
what are the serum levels of
- calcium
- phosphate
- PTH
- alk phos
in osteoporosis?
- NORMAL calcium
- NORMAL phospate
- NORMAL PTH
- NORMAL alk phos
what are the treatments for osteoporosis?
- exercise, vitamin D, calcium
- bisphosphonates: induce apoptosis of osteoclasts
what is the pathophysiology of paget disease of bone?
- imbalance between osteoclast and osteoblast function that is divided into three stages:
- osteoclastic: heavy resorption
- mixed osteoblastic-osteoclastic: osteoclast activity is eventually extinguished
- osteoblastic: work overtime in a haphazard way in an attempt to repair
biopsy of paget disease of bone reveals what morphology?
mosaic pattern of lamellar bone
what are the lab findings in paget disease of bone?
isolated elevated alk phos
what are the treatments for paget disease of bone?
- calcitonin
- bisphosphonates
what are the complications of paget disease of bone?
- high output cardiac failure (due to AV shunts in bone)
- osteosarcoma
in children, osteomyelitis usually seeds what part of the bone?
metaphysis
in adults, osteomyelitis usually seeds what part of the bone?
epiphysis
what is the most common organism responsible for osteomyelitis in sexually active young adults?
n. gonorrhoeae
what is the most common organism responsible for osteomyelitis in sickle cell patients?
salmonella
what is the most common organism responsible for osteomyelitis in diabetics and IV drug users?
pseudomonas
what is the most common organism responsible for osteomyelitis in cat / dog bites?
pasteurella
what is the most common organism responsible for osteomyelitis in vertebrae?
m. TB
what is the most common organism responsible for osteomyelitis overall?
s. aureus
in osteomyelitis, the lytic focus is called the ___________ and the surrounding sclerosis is called the ____________
- sequestrum
- involucrum
