Bone Cells and Matrix

Question 1

What makes up the tensile and compressive strength of bone?

Answer 1

Tensile- collagen (90% of organic component)

Compression- proteoglycan

Question 2

What are the three main types of proteins in bone matrix?

Answer 2

Ostecalcin- most abundant aside from collagen (made by osteoblasts
Osteonectin
Osteopontin

Question 3

What is the main inorganic component of bone?

Answer 3

Calcium hydroxyapatite Ca10(PO4)6(OH)2

Question 4

Where are osteoblasts derived?

Answer 4

Undifferentiated mesenchymal cells; which then form osteoprogenitor cells

Question 5

What is the function of the core binding factor alpha-1 (Cbfa1/Runx2)?

Answer 5

Osteoblastic differentiation

Question 6

Which cell type releases RANKL?

Answer 6

Osteoblast

Question 7

Which cell type has RANK?

Answer 7

Osteoclast;

PTH binds to osteoblasts that release RANKL that binds to RANK on osteoclasts

Question 8

What is osteoprotegrin’s role?

Answer 8

Binds to RANKL and inhibits osteoclast activation; secreted by osteoblasts

Question 9

What cell are osteoclasts derived from?

Answer 9

Macrophages

Question 10

Vitronectin is an important receptor involved in which of the following functions?

Answer 10

Osteoclasts attaching to bone

Question 11

What is the function of cathepsin K?

Answer 11

Bone resorption; secreted by osteoclasts

Question 12

What substances inhibit osteoclasts?

Answer 12

1) Calcitonin
2) Osteoprotegrin
3) IL-10
4) Bisphosphonates (disrupts ruffled border)