Bone Hard 🍆💦

Question 1

Osteoid =

Made by
What is in
Looks

Answer 1

Extra cellular matrix 
Secretes by osteoblasts 
Type 1 collagen 
Gags and proteglycans 
Pale pink histology

Question 2

Resorption cavities=

Answer 2

Howships lacunae

Depressions that osteoclasts create

Question 3

Osteon=

Answer 3

Central Haversion canal with blood vessel. This canal surrounded by concentric rings of lamellar bone w osteocytes

Question 4

Haversion canal=

Answer 4

Route for blood vessel within bone

Question 5

Clavicle is annoying. Why

Answer 5

It’s a frickin flat bone !

Question 6

Osteoblasts secretes what

Answer 6

Osteoid and RANK L

Question 7

Volkmanns canal=

Answer 7

Canal for blood vessels that runs perpendicular to Haversian canals/osteons , connecting them up.

Question 8

Effect of rank L

Answer 8

Activates osteoclasts.

Attached to osteoclast precursor (monocyte) allowing them to go and remodel bone. Because it allows the rank ligand to bind to the rank part of monocytes/osteoclasts

Question 9

What blocks activation of monocytes-> osteoclasts

Answer 9

OPG

Osteoprotegrin

Question 10

What does OPG block

Answer 10

It stop activation of osteoclasts by stopping rank ligand binding to rank(on the osteoclast itself) as opg binds to the rank ligand itself

Question 11

What is opg used to treat

Answer 11

Bone loss, osteoporosis

It lowers osteoclast activity so less bone chewwwwed

Question 12

How many layers of cells in synovial joints

Answer 12

1-4

Question 13

Types of cells in synovial joints

Answer 13

Type A - phagocytes

Type b- rich in RER, secrete synovial fluid

Question 14

What inhibits bone resorption

Answer 14

Bone resorption is chewwwing by osteoclasts

So OPG
And calcitonin

Question 15

Long bone formation

Answer 15

Endochondrial

• from cartilage to bone

Question 16

Flat bone (and irregular bone) formation

Answer 16

Intramembranous

• from mesenchymal cells

Question 17

Ossification centres =

Answer 17

Bone laid down (osteoblasts) on top of hyaline cartilage (chondrocytes)

Primary= middle of bone
Secondary= ends of bone

Question 18

What happens to ossification centre

Answer 18

Osteoclasts break down to leave a medullary cavity

Question 19

Mineralisation

When
What
Regulated by

Answer 19

Intramembranous ossification

Hydroxyapatite crystals laid down (calcium and phosphate)

Hardens bone- spicules created which then fuse to trabeculae

Vit d and PTH

Question 20

Healing

Direct-

Answer 20

Osteoclasts cute tunnels and osteoblasts fill them in, across fracture

Stable fracture

Question 21

Healing
- / indirect

4 stages

Answer 21

Unstable fractures

1 inflammation- haemotoma (clotted blood swelling inc wbc) stabilises

2 soft callus formation - fibroblasts and collagen , replaces haemotoma

3. Hard callus formation- endochondrial ossification to create woven bone
4. Remodelling - woven bone becomes lamellar

Question 22

Macro bone types

Answer 22

Corticol = compact , dense

trabecular- spongy, cancellous. (Light) Holes . Often filled with bone marrow

Question 23

Micro. Bone types

Answer 23

Primary/ woven— made quickly, disorganised

Secondary - lamellar/- made slowly, layered . Replaces woven