Bones I Flashcards
(46 cards)
1
Q
RANK pathway (2):
A
- RANKL on osteoblast and marrow stromal cells
- RANK receptor on osteoclast precursor allows osteoclast generation and survival
2
Q
M-CSF Pathway (2):
A
- M-CSF secreted by osteoblast
- M-CSF receptor allows osteoclast generation and survival
3
Q
WNT/Beta-catenin pathway (3):
A
- WNT from marrow stromal cells
- LRP5 and LRP6 osteoblast receptor bind WNT protein
- Secrete OPG which blocks RANK
4
Q
Bone composition (2):
A
- Calcium hydroxyapatite (mineral portion)
- Organic matrix mostly type 1 collagen
5
Q
Osteopontin:
A
Unique to bone, levels parallel osteoblast activity
6
Q
Alkaline phosphatase:
A
From osteoblasts, also in liver and placenta
7
Q
Woven bone (4):
A
- Random collagen deposition
- Rapid bone growth
- Resists forces all directions
- Always pathologic in an adult
8
Q
Lamellar bone (3):
A
- Ordered collagen deposition
- Replaces woven bone
- Stronger than woven bone
9
Q
Epiphysis:
A
Distal to growth plate.
10
Q
Metaphysis:
A
Beneath growth plate
11
Q
Diaphysis:
A
Center of bone
12
Q
Dysostosis:
A
- Local* problems in migration of mesenchyme and their condensation.
- Eg. polydactyly/brachydactyly
13
Q
Dysplasia:
A
Global defect in regulation of skeletal organogenesis
14
Q
Cleidocranial dysplasia (6):
A
- Autosomal dominant
- RUNX2 transcription factor defect
- Short stature
- Abnormal clavicles
- Supernumerary teeth
- Wormian bone
15
Q
Achondroplasia (4):
A
- Growth plate defect from paracrine cell defect
- Reduced chondrocyte proliferation in growth plate
- FGFR3 point mutation –> gain of function
- Autosomal dominant
16
Q
Achondroplasia appearance (5):
A
- Short stature
- Short proximal limbs
- Normal trunk length
- Enlarged head with bulging forehead
- Depression of root of nose
17
Q
Thanatophoric dwarfism (6):
A
- Most common lethal dwarfism
- Cloverleaf skull
- More severe FGFR3 gain of function mutation
- Micromelic short bowed limbs
- Small underdeveloped chest with bell-shaped abdomen
- Diminished chondrocyte proliferation
18
Q
LRP5 - Gain of function:
A
Cannot upregulate osteoclasts
- Autosomal dominant osteopetrosis type 1
19
Q
Osteoprorosis pseudoglioma syndrome (3):
A
- Inactive LRP5
- Skeletal fragility
- Loss of vision
20
Q
Osteopetrosis (5):
A
- Diffuse systemic bone sclerosis
- Bone deposition replaces medullary cavity
- Bulbous long bones
- Narrow neural foramina
- Brittle bones
21
Q
Osteopetrosis is due to:
A
Reduced osteoclast bone resorption
- Cannot acidify pit
22
Q
Autosomal dominant benign osteopetrosis (6):
A
- Adolescent or adulthood
- Multiple fractures
- Mild anemia
- Hepatosplenomegaly
- Mild cranial nerve defects
- Can be treated with bone marrow transplant
23
Q
Osteogenesis imperfecta (4):
A
- Group of type 1 collagen diseases
- Affects other areas rich in type 1 collagen
- Autosomal dominant
- Fragility vs. child abuse
24
Q
Osteogenesis imperfecta type 1 (5):
A
- Normal stature with less fractures after puberty
- Blue sclerae from translucency of sclera
- Dentinogenesis imperfecta from dentin defect
- Hearing loss
- Joint laxity
25
Mucopolysaccharidoses (3):
- Defect in enzymes degrading dermatan sulfate, heparan sulfate and keratan sulfate
- Abnormalities of hyaline cartilage
- Malformed bones
26
Osteoporosis:
Increased bone porosity and decreased mass
27
Aging causes of osteoporosis (4):
- Decreased replicative activity of osteoprogenitor cells
- Decreased synthetic activity of osteoblasts
- Decreased biologic activity of matrix-bound growth factors
- Reduced physical activity
28
Menopausal causes of osteoporosis (4):
- Decreased serum estrogen
- Increased cytokines
- Increased expression of RANK, RANKL
- Increased osteoclast activity
29
Low turnover variant of osteoporosis:
Senile osteoporosis
30
High turnover variant of osteoporosis:
Post-menopausal osteoporosis
31
Secondary osteoporosis (3):
- Hyperparathyroidism
- Corticosteroids
- Immobilization
32
Brown tumor (3):
- Bone loss due to hyperparathyroidism replaced by fibrovascular tissue
- Microfractures result in hemorrhage and healing
- Granulation tissue and hemosiderin
33
Paget disease of bone stages (3):
- Osteolytic stage: osteoclast activity
- V-shaped lesion
- Mixed stage: osteolytic and osteoblastic
- Osteosclerotic stage: Mosaic pattern of lamellar bone due to osteoblasts
34
Paget disease labs (2):
- Increased alkaline phosphatase
| - Normal calcium and PO4
35
Paget disease: bone overgrowth can lead to (4):
- Cranial nerve palsy
- Heavy skull
- Severe secondary osteoarthritis
- Chalk stick-type fracture
36
Fracture - soft tissue callus (4):
- Hematoma fibrin creates framework
- Influx inflammation, fibroblasts and capillaries
- Osteoprogenitor cells activated
- No rigidity, easily disrupted
37
Fracture - boney callus (4):
- Woven bone
- +/- cartilage for enchondral ossification
- Maximum girth of callus 3 wks
- Over time remodels to bear full weight
38
Osteonecrosis (3):
Avascular necrosis
- Infarction of bone and marrow
- Corticosteroids most common cause
- Dead bone/fat replaced by Ca++ salts
39
Causes of avascular necrosis (6):
- Idiopathic
- Corticosteroids
- Infection
- Dysbarism
- Pregnancy
- Sickle cell disease
40
Subchondral infarct (2):
- Chronic pain
| - Wedge-shaped subchondral bone
41
Osteomyelitis:
Bone inflammation almost always from infection
42
Location of pyogenic osteomyelitis by age (3):
- Neonate: metaphysis and/or epiphysis
- Children: metaphysis
- Adult: epiphyses and subchondral bone
43
Sequestrum:
Dead piece of bone
44
Brodie Abscess:
Small intraosseous abscess often in the cortex walled off by reactive bone
45
Involucrum:
Reactive surrounding bone
46
Potts disease:
TB infection of spine
