Bone Histology (Lect) Flashcards Preview

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Flashcards in Bone Histology (Lect) Deck (77)
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1

What are the two types of bone developement?

Endochondral
Intramembranous

2

What kind of bone usually developes intramembranously?

flat bones (e.g skull bones)

3

What happens if blood vessels are near mesenchyme?

they enlarge and will become bone rather than cartilage

4

How do mesenchymal cells condense yet remain attached to each other?

they maintain their gap junctions

5

What do mesenchymal cells first differentiate into on their way to becoming bone?

Osteoprogenitor cells

6

What do osteoprogenitor cells differentiate into?

Osteoblasts

7

What is osteoid?

a non-mineralized matrix laid down by osteoblasts that later mineralizes into a bone spicule (aka canaliculi)

8

What happens when osteoblasts become trapped and can no longer divide?

they become osteocytes

9

Does osteoid stain dark?

NO

10

What is deposited that causes bone calcification?

hydroxyappetite

11

What is formed by bone spicules growing together?

Spongy bone

12

What is absolutely essential for bones to live?

blood supply

13

What is the osteogenic layer?

The outer layer of osteoblasts that line up on the outside and inside during intramembranous bone formation to lay down compact bone

14

What are the two layers of periosteum?

The fibrous layer and the osteogenic layer

15

What type of cell is formed by the fusion of monocytes from bone marrow?

osteoclasts

16

What hormone accelerates the activity of osteoclasts?

parathyroid hormone (happens when Ca2+ and PO4 are low)

17

What hormone slows the activity of osteoclasts?

calcitonin

18

T or F: osteoclasts are mononucleated?

False

19

Describe the location and activity of osteoblasts and osteoclasts in the widening of bone?

osteoblast must be working to build bone on the exterior
osteoclasts must work to clean away bone on the interior

20

Increase in bone width is an example of?

appositional growth

21

T or F: all bones have both spongy and compact bone

True - all bones have this component, it doesn't matter how it formed

22

What is the point of having weaker spongy bone in the interior of bones?

it helps reduce bone weight

23

When the growth plate recedes what is formed?

epiphyseal line

24

What happens to red marrow as you age?

some of the red marrow may be converted to yellow marrow

25

How many cells thick is the endosteum?

1 layer thick

26

How is bone decalcification performed for preparation methods?

acid is used to extract the mineral

27

What is the consistency of bone that has been decalcified?

tough and rubery, and can be cut like any other tissue

28

What is the ground method of bone prep?

bone is cut with a diamond saw and ground until its thin enough to see through, no stains are used

29

What do dark areas in ground bone represent?

air

30

What are haversian systems?

concentric rings (lamelae) that contain osteocytes in a lacuna
These form around haversian canals that contain and artery and vein
canaliculi permit nutrition to move from artery to cell