Path - Bones

Question 1

function of osteoblasts

Answer 1

synthesize, transport, and assemble matrix

regulate mineralization

Question 2

compare osteocytes and osteoblasts

Answer 2

osteocytes are inactive osteoblasts with less cytoplasm

Question 3

what bone cells have canaliculi and what do they use them for

Answer 3

osteocytes

use them as tunnels that the osteocyte dendritic processes use to network

Question 4

describe the chemicals associated with building bone and those with breaking down bone

Answer 4

build: estrogen, testosterone, vitamin D
breakdown: PTH, IL-1, glucocorticods

Question 5

define dysostosis and what genes it is related to

Answer 5

migration and condensation of mesenchyme and differentiation into cartilage anlage

associated with homeobox genes

Question 6

define syndactyly/craniosynostosis

Answer 6

abnormal fusion of bone

Question 7

is dysplasia of bone pre-malignant?

Answer 7

no

Question 8

what are the differences between OI type 3 and 4

Answer 8

type 3:

• fractures present at birth
• short stature
• blue, purple, grey sclera
• loose joints and poor muscle development
• more definitive spinal curvature
• often severe bone deformity

type 4:

• fractures mostly before puberty
• shorter than average
• white/near white sclera
• tendency towards spinal curvature

Question 9

what are the similarities between OI type 3 and 4

Answer 9

• improperly formed collagen
• barrel-shaped rib cage
• triangular face
• brittle teeth possible
• hearing loss possible

Question 10

mutation in CLCN7 indicates

Answer 10

osteopetrosis (marble bone dz, albers-schonerg dz)

Question 11

CA2 deficiency indicates

Answer 11

osteopetrosis (marble bone dz, albers-schonerg dz)

Question 12

bones that lack a medullary cavity indicate

Answer 12

osteopetrosis (marble bone dz, albers-schonerg dz)

Question 13

erlenmeyer flask bone findings on x-ray indicate

Answer 13

osteopetrosis (marble bone dz, albers-schonerg dz)

Question 14

optic atrophy, deafness, and facial paralysis cranial nerve deficits are indicative of what bone dz

Answer 14

osteopetrosis (marble bone dz, albers-schonerg dz)

Question 15

defects in acid hydrolase enzymes are associated with what disease group

Answer 15

mucopolysaccharidoses

Question 16

what happens to the bone in mucopolysaccharidoses

Answer 16

chondrocytes degrade ECM mucopolysaccharides –> mucopolysaccharides accumulate in chondrocytes in the extracellular space –> structural defects in articular cartilage

Question 17

clinical presentation of a patient with mucopolysaccharidoses

Answer 17

short stature, chest wall abnormalities, malformed bones

Question 18

atraumatic or vertebral compression fracture indicates

Answer 18

osteoporosis

Question 19

what genetic factors are associated with osteoporosis

Answer 19

LRP5 single gene defect

also RANKL, OPG, RANK, HLA, estrogen receptor gene, vitamin D receptor gene

demo: caucasian with light colored hair and eyes

Question 20

what treatment for breast cancer has been associated with osteoporosis

Answer 20

tamoxifen

Question 21

what are some secondary causes for osteoporosis

Answer 21

renal or hepatic failure, hyperthyroidism

Question 22

SQSTM1 gene mutation is associated with what dz

Answer 22

sporadic paget disease

not familial

Question 23

“cotton wool” finding on x-ray indicates what dz

Answer 23

paget dz

Question 24

what types of fractures occur in paget dz

Answer 24

chalk-stick type fx of long bones of legs

Question 25

leontiasis ossea (lion face) and platybasia (invagination of skull base) are associated with what dz process

Answer 25

paget dz

Question 26

bowing out of lower limbs with increased warmth and tenderness over the bones indicates what dz

Answer 26

paget dz

Question 27

compare rickets and osteomalacia

Answer 27

both vitamin D deficiency or abnormal metabolism of vitamin D

Rickets: children, interferes with deposition of bone in the growth plate

osteomalacia: adults, bone formed during remodeling is under-mineralized –> predisposing to fractures

Question 28

clinical sx of rickets

Answer 28

• bowed legs
• frontal bossing (large forehead)
• squared off head
• rachitic rosary of ribs
• anterior protrusion of chest (pigeon breast)
• lumbar lordosis

Question 29

“railroad track” bones indicate what dz

Answer 29

hyperparathyroidism causing dissecting osteitis

Question 30

why is renal osteodystrophy called the “silent crippler”

Answer 30

the bone changes from renal osteodystrophy can begin many years before sx appear in adults with kidney dz

Question 31

what is osteonecrosis

Answer 31

infarction of the bone and marrow

Question 32

compare subchondral and medullary infarcts in osteonecrosis

Answer 32

subchondral: cause pain and are initially associated only with activity, then becomes constant
medullary: usually small and clinically silent

Question 33

80-90% of osteomyelitis cases are caused by what organism

Answer 33

s. aureus

Question 34

osteomyelitis in a sickle cell patient is often caused by what organism

Answer 34

salmonella

Question 35

what is seen on histology in mycobacterial osteomyelitis

Answer 35

caseous necrosis and granulomas