MSK Flashcards
Activating mutation in FGFR3 (fibroblast growth factor)
Achondroplasia –> this activating mutation INHIBITS growth = impaired cartilage proliferation (chondrocrytes at growth plate) = short extermities with normal head/chest
inherited defect of bone resporption
Osteopetrosis –> abnomally thick, heavy bone that fractures easily
Carbonic anhydrase mutation leading to bone condition
Osteopetrosis. Lose the acidic environment needed for bone resorption.
Thick bone compressing cranial nerves
Vision and hearing loss in Osteopetrosis
Tx for Osteopetrosis
bone marrow transplant –> normal monocytes = ability to make normal osteoclasts
Cell with poor function in Osteopetrosis
osteoclast (can’t resorb the bone)
Defective mineralization of osteoid
rickets/osteomalacia –> low vit D. Osteoid (put down by osteoblasts) is normally mineralized with calcium and phosphate = bone
Frontal bossing (osteoid deposition), rachitic rosary (feel osteoid @costochondral j(x)), bowing of legs, Pigeon-breast deformity (ribs bend in, sternum protrudes anteriorly)
Osteomalacia/rickets = defective mineralization of osteoid
low calcium, low phosphate, increased PTH, increased Alkaline phophatase
osteomalacia (low vit D in adults). decreased vit D–>decreased Ca–> increased PTH–> decreased PO4.
Increased ALP because get hyperactivity of osteoblasts.
reduction in trabecular bone mass (porous bone)
Osteoporosis
lab values in osteoporosis
normal calcium, phosphate, PTH, and ALP –> NO ABNORMAL LABS IN OSTEOPOROSIS
pharm induction of osteoclast apoptosis
Bisphosphonates…tx osteoporosis
Imbalance btwn osteoclast and osteoblast
Paget
isolated elevated ALP
Paget
increased hat size
Paget
Hematological implications of osteopetrosis
Bony replacement of marrow (myelothisic) = pancytopenia!! + extra medullary hematopoeisis
thick sclerotic bone that fractures easily
Paget (prob applies to Osteopetrosis also)
lytic focus (abscess) surrounded by sclerosis of bone on xray
Osteomyelitis
multiple colon polyps + osteoma
FAP + benign bone tumor = Gardners
most common benign bone tumor
osteochondroma (male
bone tumor with bimodal distribution
Osteosarcoma: teenagers (familial retinoblastoma) and elderly (Paget dx and radiation)
malignant bone tumor in the knee region vs benign tumor in knee region
Osteosarcoma (malignant; metaphysis) vs Giant cell tumor (benigng; epiphysis)
Codman triangle and mass with sunburst appearance
osteosarcoma
pleomorphic osteoid producing cells
Osteosarcoma (malignant prolif of osteoblasts)
only bone tumor in the epiphysis
Giant cell tumor
Bone tumor with “soap bubble” appearance
Giant cell tumor
Neuroectoderm derived bone tumor
Ewings sarcoma
Malignant bone tumor in diaphysis in male boys
Ewing sarcoma. 11,22 translocation
metastatic bone tumor lesions
generally osteolytic (punched out). exception = prostatic carcinoma = osteoblastic = sclerosis.
cartilage w/in a joint capsule
Articular cartilage = hyaline
fluid in joint capsule
synovial lining secretes fluid rich in Hyaluronic acid
morning stiffness that gets worse throughout the day
osteoarthritis
bone pain that resolves with aspirin
Osteoid osteoma (
What’s the voltage-sensor coupled to RyR on the SR
Dyihropyridine receptor (v-gated Ca sensor)
Release of ADP and inorganic P04 from myosin:
power stroke (displacement of myosin on the actin filament)
relationship of tropomyosin, actin, myosin, troponin, Ca
Tropomyosin covers the myosin binding site on actin. Ca binds to troponin which moves the tropomyosin.
Change in bands during contraction
A is Always the same…doesnt change
H and I are shortened, and Z lines move toward each other
bands of sarcomere
A: thick filament
H band: area of thick filament with no overlap from thin
I band: area of thin filament wit no overlap from thick
Z-Z: sarcomere
muscle fibers that are hypertrophied in weight training
Type 2: fast twitch/white fibers..increased anaerboic metab in these. (vs type 1 = slow twitch and red).
NO mediated smooth m relaxation
NO + on GC = increased cGMP, which + on Myosin Light Chain Phosphatase = dephophorylate Myosin = relaxation
Chondrocytes lay cartilaginous model of bone –> osteclasts/blasts replace with woven–> remodel to lamellar
Endochondral ossification. Bones of axial and appendicular skeleton
Woven bone formed directly without cartilage
membraneous ossification: bones of calvarium and face.
Woven bone seen in adult
after fractures and Paget’s disease
Osteoclasts
Multinucleated cells that dissolve bone
low vs high levels of PTH
low levels: build bone (anabolic)
chronically increased PTH i.e. hyperparathyroid: catabolic (osteitis fibrosa cystica)
Estrogen role in bone cells
inhibits apoptosis in osteoblasts; induces apoptosis in osteoclasts
deficiency can lead to osteoporosis
Osteoblast markers
bone-specific Alkaline Phosphatase (ALP)
osteoclast markers
TRAP and urinary deoxypyridinoline