Bones 1 Flashcards
what are the 3 types of cell in bone ? how many nuclei? basic multicellular unit
osteoclasts ( multiple_
osteoblasts (single nucleus)
osteocytes
RANKL located on what cell
osteoblasts and marrow stroma cells
RANK is located on what cell? role?
osteoclast precursor
- allow OC generation and survival
explain the M-CSF pathway
- M-CSF secreted by OB
2. M-CSF binds to OC: generation and survival
explain the WNT/Beta-catenin pathway
- WNT from marrow stromal cell
- LRP5 and LRP6 OB receptor bind WNT protein
- OB secretes OPG ( blocks RANK)
bone compositition
calcium hydroxyapatite
organic matrix with type I collagen
what are the two types of bone? where are they found
woven bone: random collagen
lammellar bone: ordered collagen
compact bone
spongy bone
name two bone enzymes
osteopontin
alkaline phosphatase
role of osteopontin ( osteocalcin)
levels parallel osteblast activity
alkaline phosphatase comes from what organ
osteoblasts
liver and placenta
woven bone?
how fast does it grow?
forces?
rapid bone growth
resists forces in all directions
pathologic in adults
lamellar bone replaces what
woven bone
stronger than woven bone
what process forms bone?
intramembranous ossification
- direct from mesenchyme
- appositional growth
location of epiphysis
distal to growth plate
location of metaphysis
beneath growth plate
location of diaphysis
center
Dysostosis
local problems in migration of mesenchyme and their condensation
dysplasia
global defect in regulation of skeletal organogenesis
Cleidocarnial dysplasia
- inherited
- defect protein
autosomal dominant
-RUNX2 (CBFA1)
clincial presentation for Cleidocranial dysplasia
short
abnormal clavicle
supernumery theeth
wormian bone ( extra sutural bone)
what goes wrong in achondroplasia
- growth plate defect from paracrine cell defect
- reduced chondrocyte proliferation in growth plate
achondroplasia is a defect in what gene? what does it cause
FGFR3 point mutation
-inhibits cartilage growth
how is achondroplasia passed on to generations
paternal allele
autosomal dominant
what growth is still present for achondroplasia? what does this cause
appositional and intramembranous bone formation
-thick cortical bone
clinically what does achondroplasia look like
short proximal limbs normal turnk enlarged head depression of root nose normal reproductive and intelligence
what is the most common lethal dwarfism
Thanatophoric dwarfism
thanatrophoric dwarfism is a mutation in what
FGFR3
clinical presentation of thanatophoric dwarfism
cloverleaf leaf
bell-shaped abdomen
LRP5 is a receptor that activates what
WNT/beta-catenin in OB
- produces OPG (Blocks RANKL)
what disease has an inactive LRP5
osteoporosis pseudoglioma syndrome
- skeletal fragility
- loss of vision
Marble bone disease
osteopetrosis
what goes wrong in osteopetrosis
reduced osteoclast bone resorption
- cannot acidify pit
- defect in RANKL
LRP5 gain of function
in osteopetrosis bone deposition replaces what
medullary cavity
- no room for hematopoiesis
what does osteopetrosis look like on X-ray
Erlenmeyer flask
how is osteopetrosis passed down
autosomal dominant
brittle bone disease
osteogenisis imperfecta
Osteogensis imperfecta what goes wrong
type 1 collagen disease
- mutation of alpha 1 and 2 chains
extreme skeletal fragility
what is the most common type of autosomal dominant bone disease
osteogenisis imperfecta
clinical features of Autosomal dominant osteogensis imperfecta
blue sclera
hearing loss
dentin defect
Type 2, 9, 10, 11 collagen disease has a defect in what?
hyaline cartilage
-
Mucopolysaccharidoses is a defect in what
enzymes degrading dermatan sulfate, heparan sulfate, keratan sulfate
- abnormal hyaline cartilage
- malformed bone
what is osteoporosis
increase bone porosity
decrease mall
primary osteoporosis
senile, postmenopausal
secondary osteoporosis
drugs, diabetes,
compare osteoporosis and osteopenia
osteopenia: decrease bone mass
osteoporosis: osteopenia to point of risk of fracture
senile osteoporosis what happens to the osteoblasts? cortex?
reduce metabolism
cortex is thinned
when is skeletal mass peak for senile osteoporosis
young adult
in postmenopausal osteoporosis what happens when estrogen is decreaed
increase inflammatory cytokines
increase RANKL
decrease OPG
OC>OB
rickets
child vitamin D deficiency
osteomalacia
adult vitamin D deficiency
renal osterodystrophy
chronic renal disease
- increase or decreased OC/OB activity
- decrease Vitamin D conversion
what happens to OC and OB in hyperparathyroidsim
more OC
what does the X-ray look like for hyperparathyroidsim
bone loss radial aspect of middle phalange of index and middle finger
-osteopenia
Paget disease involve what bone
axial skeleton
proximal femur
what are the 3 stages of paget disease
osteolytic stage
mixed stage
osteosclerotic stage
osteolytic stage
loss of bone mass
mixed stage
osteolytic and osteoblastic
osteosclerotic stage
jigsaw puzzle-like cement lines of lamellar bones
paget disease has an increase in what enzyme? what values stay the same
alkaline phosphatase
normal Ca and PO4
Paget disease: pain overgrowth can lead to
cranial nerve palsy
heavy skull
what happens to the skin in Paget disease
warm skin over affected bone with hypervasculatiry
-high-output cardiac failure
treatment for Paget disease
Calitonin and biphosphonates
bony callus
woven bone
-overtime can bear weight
Soft tissue callus
easily disrupted
hematoma fibrin
osteoprogentor cells activated
peak bone mass
early adulthood
how can a genetic factor cause osteoprosis
vit D receptor polymorphism
is an X-ray and serum levels of calcium, phosphorous, alkaline phosphate helpful in diagnosing osteoporosis
NO
osteitis fibrosa cystica
severe form of parathyroidsm
pseudoarthrosis
non union
osteonecrosis
infarction of bone marrow
most common cause of osteonecrosis
corticosteroid
in osteonecrosis what is dead bone/fat replaced by
Ca soaps
name 5 things that can cause avascular necrosis
corticosteroid pregnancy infection dysbarism sickle cell disease
subchondral infarct what doe sit look like
wedge-shaped subchondral bone
osteomyelitis
inflammation almost always from infection
how does bacteria reach bone
hematogenous
direct
implantation
X-ray for osteomyelitis
lytic bone lesion with surrounding sclerosis
most common bacteria in pyogenic osteomyelitis
s. aureus
most common bacteria in pyogenic osteomyelitis for infants
group B
H. influencza
where does pyogenic osteomyeltissi occur in bone in neonate
children
adult
neonate: metaphysis/epophysis
children: metaphysis
adult: epiphysis and subchondral bone
sequestrum
dead piece of bone
brodie abscess
small intraosseous abscess often in cortex walled off by reactive boone
involucrum
reactive surrounding bone
process of pyogenic osteomyelitis
sequestrum
chronic inflammation : brodie abcxess
involucrum
congential syphilis
at enchondral ossification centers and periosteum
acquired syphilis of bone? what type of bone and clinical presentsion
bone in tertiary phase
saddle nose, saber shin ( tibia)
