18.1 - Skeletal system

Question 1

achondroplasia is due to impaired cartilage proliferation in the _______________

Answer 1

growth plate

Question 2

achondroplasia is due to a mutation of what gene? what type of mutation is it?

Answer 2

• FGFR3

- activating mutation

Question 3

what is the inheritance of achondroplasia?

Answer 3

AD

Question 4

is achondroplasia a defect in endochondral or intramembranous bone formation?

Answer 4

endochondral

Question 5

what is the inheritance of osteogenesis imperfecta?

Answer 5

AD

Question 6

osteogenesis imperfecta is a defect in type ____ collagen synthesis

Answer 6

1

Question 7

why are blue sclerae seen in osteogenesis imperfecta?

Answer 7

thinning of scleral collagen reveals underlying choroidal veins

Question 8

osteopetrosis is due to poor function of what cell type?

Answer 8

osteoclast

Question 9

what is the most common gene mutation variant leading to osteopetrosis? what is the result?

Answer 9

carbonic anhydrase II - loss of acidic microenvironment required for bone resorption

Question 10

what are the hematologic manifestations of osteopetrosis? what is the mechanism?

Answer 10

• anemia
• thrombocytopenia
• leukopenia
• extramedullary hematopoiesis
• due to bony replacement of marrow (myelophthisic process)

Question 11

what is the treatment for osteopetrosis?

Answer 11

bone marrow transplant

Question 12

rickets / osteomalacia is due to what process?

Answer 12

defective mineralization of osteoid

Question 13

• pigeon breast deformity
• frontal bossing
• rachitic rosary
• bowing of the legs

Answer 13

rickets

Question 14

what are the serum levels of

• calcium
• phosphate
• PTH
• alk phos

in osteomalacia?

Answer 14

• low calcium
• low phosphate
• high PTH
• high alk phos

Question 15

when osteoblasts are activated, what does that do to alk phos levels?

Answer 15

increase

Question 16

osteoporosis is a reduction in bone mass of what type of bone?

Answer 16

trabecular

Question 17

what are the serum levels of

• calcium
• phosphate
• PTH
• alk phos

in osteoporosis?

Answer 17

• NORMAL calcium
• NORMAL phospate
• NORMAL PTH
• NORMAL alk phos

Question 18

what are the treatments for osteoporosis?

Answer 18

• exercise, vitamin D, calcium

- bisphosphonates: induce apoptosis of osteoclasts

Question 19

what is the pathophysiology of paget disease of bone?

Answer 19

• imbalance between osteoclast and osteoblast function that is divided into three stages:
• osteoclastic: heavy resorption
• mixed osteoblastic-osteoclastic: osteoclast activity is eventually extinguished
• osteoblastic: work overtime in a haphazard way in an attempt to repair

Question 20

biopsy of paget disease of bone reveals what morphology?

Answer 20

mosaic pattern of lamellar bone

Question 21

what are the lab findings in paget disease of bone?

Answer 21

isolated elevated alk phos

Question 22

what are the treatments for paget disease of bone?

Answer 22

• calcitonin

- bisphosphonates

Question 23

what are the complications of paget disease of bone?

Answer 23

• high output cardiac failure (due to AV shunts in bone)

- osteosarcoma

Question 24

in children, osteomyelitis usually seeds what part of the bone?

Answer 24

metaphysis

Question 25

in adults, osteomyelitis usually seeds what part of the bone?

Answer 25

epiphysis

Question 26

what is the most common organism responsible for osteomyelitis in sexually active young adults?

Answer 26

n. gonorrhoeae

Question 27

what is the most common organism responsible for osteomyelitis in sickle cell patients?

Answer 27

salmonella

Question 28

what is the most common organism responsible for osteomyelitis in diabetics and IV drug users?

Answer 28

pseudomonas

Question 29

what is the most common organism responsible for osteomyelitis in cat / dog bites?

Answer 29

pasteurella

Question 30

what is the most common organism responsible for osteomyelitis in vertebrae?

Answer 30

m. TB

Question 31

what is the most common organism responsible for osteomyelitis overall?

Answer 31

s. aureus

Question 32

in osteomyelitis, the lytic focus is called the ___________ and the surrounding sclerosis is called the ____________

Answer 32

- sequestrum | - involucrum