OB-Bone and cartilage

Question 1

What is bone composed of?

Answer 1

60% inorganic (hydroxyapatite)

15% water

25% organic (mainly collagen but also glycoproteins and proteoglycans)

Question 2

What glycoproteins are found in bone?

Answer 2

Osteocalcin

Osteonectin

Osteopontin

Sialoproteins.

Question 3

What does the extracellular matrix consist of?

Answer 3

Ground substance:

Hyalyuronic acid

Proteoglycans (Chondroitin SO₄ Heparan SO₄ Dermatan SO₄ Keratan SO₄

Fibres:

Collagen and elasticin

Question 4

What is cortical bone?

Answer 4

The dense outer bone.

Question 5

How is cortical bone arranged?

Answer 5

It is laid down in concetric lamellae that form longitudinal columns.

The lamellae layers are organised in to the haversian system around central haversian canals.

Question 6

what are volkman’s canals?

Answer 6

Lateral canals that join between the haversian canals.

Question 7

WHat are canicului?

Answer 7

These are found around the osteocytes and allo wthe osteocytes to comunicate with each other and access the bone blood supply.

Question 8

What is cancellous bone?

Answer 8

A network of thin trabeculae (Scaffolding)

In the space between the trabeculae we have bone marrow.

Question 9

Compare Cortical bone to cancellous bone?

Answer 9

Cortical bone has the haversian system (blood vessels)

whereas cancellous bone does not have blood vessels (nutrients diffuse in instead)

Question 10

Why is the type of bone relevant for dentistry/

Answer 10

Cortical bone is found lining the tooth sockets

AND

There is a greater sucess for implants with cortical bone.

Question 11

Compare woven and lamellar bone

Answer 11

Lamellar bone is slowly laid down whereas woven is laid down rapidly.

Lamellar bone has collagen fibres laid down in parallel. Woven bone has irregular deposition of collagen

Lamellar is found in adults. Woven is found in the fetus or where fractures are being repaired.

Lamellar contains fewer osteocytes, Woven contains many osteocytes.

Question 12

What is howships lacunae?

Answer 12

A depression caused by bone resorption where you find osteoclasts

Question 13

What is the line shown in this image?

Answer 13

The reversal line which shows the moment where resorption is converted to bone deposition.

Question 14

What is cartilage?

Answer 14

An unmineralised avascular connective tissue.

Question 15

Compare the different types of cartilage

Answer 15

Hyaline cartilage is flexible cartilage present everywhere

Fibrocartilage is strong cartilage used to stabilise joints.

Elastic cartilage contains additional elastic fibres.

Question 16

Compare the two ways in which bone grows:

Answer 16

Endochondral ossification where the cartilage skeleton is laid down and then replaced with bone. (in flat bone)

Intramembranous ossification where the bone is formed from the start.

(in long bone) remember as it is a longer word.

Question 17

Discuss the development of the mandibular bone.

Answer 17

The mandibular bone is produced by both processes:

The mandible is produced by intramembranous ossification

The condylar process/ alveolar process and coronoid process are produced by endocrhondral ossification.

Question 18

What is shown in this microscopic image

Answer 18

This meckel’s cartilage which is a dense peice of cartilage that provides a framework for development of the mandible.

Question 19

What is produced by Meckel’s cartilage?

Answer 19

The Sphenomandibular ligament