Bone, Cartilage and Osteogenesis - Hovorka

Question 1

What are the 3 types of cells found in bone?

Answer 1

Osteoblasts
Osteocytes
Osteoclasts

Question 2

Where are osteoblasts found?

Answer 2

At border between bone and periosteum

Question 3

What do osteoblasts secrete?

Answer 3

Uncalcified bone matrix

Question 4

Osteoblasts differentiate from what? Where?

Answer 4

Progenitor cells

Periosteum

Question 5

From what do osteocytes differentiate?

Answer 5

Osteoblasts - only once they are surrounded by calcified bone matrix

Question 6

Where are osteocytes found?

Answer 6

In lacunae

Question 7

How do osteocytes receive nutrients?

Answer 7

From a central artery via their connections to neighboring cells in contact with the artery

Question 8

What type of junctions to the osteocyte processes contain?

Answer 8

Gap junctions

Question 9

What are osteoclasts?

Answer 9

Large, multinucleated cells that degrade bone matrix

Question 10

From what do osteoclasts differentiate?

Answer 10

Monocytes

Question 11

How do osteoclasts degrade bone matrix?

Answer 11

By secretion of protons and lysozomal enzymes

Question 12

Differentiation and activity of osteoclasts increases due to which hormone?

Answer 12

Parathyroid hormone

Question 13

What are the organic components of bone matrix?

Answer 13

Mostly type I collagen

Very little ground substance

Question 14

How does bon become calcified?

Answer 14

By the deposition of calcium phosphate (hydroxyapatite) around the collagen fibers, displacing water

Question 15

How is mature bone matrix organized?

Answer 15

Lamellae and osteons surrounding small central arteries

Question 16

What is periosteum made of?

Answer 16

Dense connective tissue - containing fibroblasts and collagen bundles

Question 17

The periosteum is continuous with what?

Answer 17

The tendons that insert on it

Question 18

Where are the progenitor cells contained?

Answer 18

In the periosteum

Question 19

What is the cylindrical unit of mature bone called?

Answer 19

Osteon

Question 20

What are lamellae?

Answer 20

Rings of calcified bone matrix with collagen fibers oriented in a single direction

Question 21

What contains the vessels and nerves in bone?

Answer 21

Haversian canal (central canal)

Question 22

What are canaliculi?

Answer 22

Canals that interconnect lacunae within the osteon and facilitate the transport of nutrients and wastes between osteocytes

Question 23

What interconnects central canals and periosteum/endosteum?

Answer 23

Perforating canals

Question 24

What are the 5 steps to healing bone?

Answer 24

1. Hematoma
2. Connective tissue invades
3. Precallus - hyaline cartilage model
4. Callus - calcification and ossification of cartilaginous model creates immature bone
5. Mature bone

Question 25

How do nutrients/wastes get in/out of cartilage?

Answer 25

Diffuse through the matrix to/from the surrounding perichondrium

Question 26

What are the 2 cells types in cartilage?

Answer 26

Chondroblasts

Chondrocytes

Question 27

Chondroblasts differentiate from what cells?

Answer 27

Progenitor cells

Question 28

Where are progenitor cells found?

Answer 28

Border between bone and perichondrium