MSK/Derm III Flashcards
muscle components
Z disc - actin attachment M line - myosin attach A band - all myosin H band - myosin only I band - myosin only
sarcomere - Z disc to Z disc
smooth m contraction
nitric oxide - guanylate cyclase - increased cGMP
- de-P myosin
- relaxation
action potential - L-type Ca channel - increased Ca
-increased Ca/calmodulin complex > P of myosin
myosin-P bind actin and contraction occurs
endochondral ossification
cartilage bone - replaced by osteoclasts/blasts - into woven bone
remodeled to lamellar bone
woven bone - after fx and with pagets
membranous ossification
bones of calvarium and face
woven - without cartilage
later remodel to lamellar
osteoblast
from mesenchymal stem cell in periosteum
osteoclast
from monocyte/macrophage
PTH action
low - anabolic - build bone
chronic high - catabolic - osteitis fibrosa cystica
estrogen
inhibit apoptosis of osteoblasts
induce apoptosis osteoclasts
deficient - excess remodeling - osteoporosis
achondroplasia
fail long bone growth
- affect endochondral ossification
- membranous ossification unchanged
activation of FGFR3 - inhibit chondrocyte proliferation
auto dom - full penetrance
MCC dwarfism
primary osteoporosis
loss trabecular spongy bone and interconnections
with long term steroid use, anticonvulsant, antigcoag, thyroid replacement therapy
DEXA scan
T score
colles fx
distal radius
common with osteoporosis pt
type I osteoporosis
more resorption bc of low estrogen
post-menopause
type II osteoporosis
men and women >70yo
prophylaxis - Ca and vit D
tx - bisphosphonate, PTH analog, SERM
denosumab
mAb - RANKL
osteopetrosis
marble bone disease
failure resorption
-thick dense bones that fx
bone fills marrow space - pancytopenia