bonezhisto

Question 1

What do osteoblasts come from? Osteoclasts?

Answer 1

osteoblasts = mesenchymal stem cell
osteoclasts = hematopoietic stem cell

Question 2

What is the one named sesamoid bone in the body?

Answer 2

patella

others located in hands, feet (small bone surrounded by tendon)

Question 3

What does the endosteum line?

Answer 3

All inner parts of the bone: canals, cavites. Only osteoprogenitor layer

Question 4

What does the periosteum line?

Answer 4

The outer part of the bone. Made of a connective tissue layer and a osteoprogenitor layer

Question 5

What produces osteoid?

Answer 5

osteoblasts NOT osteocytes

Question 6

What makes up osteoid?

Answer 6

organic

Type I collagen, bone matrix proteins (BMPs), GAGs

Question 7

What makes up the inorganic part of bone?

Answer 7

hydroxyapatite

Question 8

What does osteocalsin do?

Answer 8

excreted by osteoblasts, promotes calcification

Question 9

What are the two ways osteoblasts help promote calcification?

Answer 9

1. secretion of osteocalsin: brings calcium

2. secretion of alkaline phosphates: PO4- and Ca2+ make up HA

Question 10

What do the cytoplasmic extensions of osteocytes travel through? How do they communicate?

Answer 10

travel through canaliculi, communicate through gap junctions

Question 11

What are major differences between bone and calcified cartilage?

Answer 11

bone:

• type I collagen
• eosinophilic

calcified cartilage:

• type II collagen
• basophilic

Question 12

Another name for primary bone tissue

Answer 12

woven or immature bone

Question 13

Another name for secondary bone tissue

Answer 13

lamellar or mature bone

Question 14

Are spongy bone and compact bone the same histologically?

Answer 14

yes, both are lamellar

Question 15

What is the structural unit of bone?

Answer 15

osteon

central canal contains artery/nerve
surrounded by concentric lamellae circles

Question 16

What is the outer boundary of an osteon?

Answer 16

cement line

Question 17

What are the vessels that run perpendicular to haversian canals, supplying the endosteum and periosteum?

Answer 17

Volkmann’s canals

Question 18

What surrounds osteon?

Answer 18

Interstitial lamellae

remnants of old osteons

Question 19

How are new osteons made?

Answer 19

1. Osteoclasts dig a canal
2. New blood vessel and osteoprogenitor cells move down into the new canal
3. Osteoblasts start forming new bone from the outside in

Question 20

Does spongy bone contain osteons?

Answer 20

No, but it still has lamellae

Question 21

How are cells in spongy bone supplied?

Answer 21

They are close to the bone marrow, so nutrients don’t have to travel far.

Question 22

Where are osteocytes located?

Answer 22

In lacunae in between lamellae