Bone Ultrastructure

Question 1

What tissue type is bone

Answer 1

Connective tissue

Question 2

Bone function

Answer 2

Structure, protection, lipid and mineral storage, haematopoiesis

Question 3

Three types of bone cells

Answer 3

Osteoblasts, osteocytes, osteoclasts

Question 4

Osteoblasts…

Answer 4

Synthesise uncalcified ECM called osteoid

Question 5

Osteocytes

Answer 5

Are matured osteoblasts entombed in the lamellae of lacunae and monitor proteins/minerals for bone mass

Question 6

Osteoclasts

Answer 6

Mature monocytes which re absorb bone by the release of H+ and lysosomal enzymes

Question 7

ECM of bone is … and is impregnated with… in particular …

Answer 7

Highly specialised … mineral salts … hydroxyapatite crystals

Question 8

Hydroxyapatite crystals …

Answer 8

Associate with collagen fibres which makes bone hard

Question 9

Bone Matrix is organised…

Answer 9

Organised into numerous thin layers called lamellae

Question 10

Two types of bone

Answer 10

Woven bone (primary) and lamellar bone (secondary)

Question 11

Primary bone

Answer 11

Woven bone

Question 12

Secondary bone

Answer 12

Lamellar bone

Question 13

Internal layer of bone

Answer 13

Endosteum

Question 14

External layer of bone

Answer 14

Periosteum

Question 15

Two subtypes of lamellar bone

Answer 15

Compact bone and spongy bone

Question 16

In compact bone, lamellae is organised into…

Answer 16

Concentric circles

Question 17

The lamellae in compact bone surround…

Answer 17

Haversian canals

Question 18

The unit which contains osteocytes, lamellae and Haversian canals

Answer 18

Osteon

Question 19

Haversian canals are connected horizontally by…

Answer 19

Volkmann’s canals

Question 20

Haversian canals contain…

Answer 20

Neurovascular and lymphatic vessels, arteries and veins

Question 21

Volkmann’s canals contain…

Answer 21

Small vessels which join the arteries of Haversian canals

Question 22

Osteocytes are in…

Answer 22

Cavities called lacunae

Question 23

Lacunae are connected by

Answer 23

Canaliculi

Question 24

Spongy bone location

Answer 24

Interior of most bones

Question 25

Bony matrix is a 3D…

Answer 25

A 3D network of fine columns which which cross link to form trabeculae

Question 26

Trabeculae produces light…

Answer 26

Light porous bone which is resistant against multidirectional lines of force

Question 27

Spaces between trabeculae are usually filled with…

Answer 27

Yellow bone marrow

Question 28

Ossification is…

Answer 28

The process of making new bone

Question 29

Endochondrial ossification

Answer 29

Hyaline cartilage is replaced by osteoblasts secreting osteoid

Question 30

Example of a bone made by endochondral ossification

Answer 30

Femur

Question 31

Intramembranous ossification

Answer 31

Mesenchymal tissue is condensed into bone

Question 32

Bone example of intramembranous ossification

Answer 32

Flat bones such as the scapula

Question 33

Remodelling is…

Answer 33

Where osteoblasts lay down osteoid where osteoclasts have reabsorbed bone

Question 34

Osteogenesis imperfecta is…

Answer 34

Excessive synthesis of collagen from osteoblasts

Question 35

Symptoms of osteogenesis imperfecta

Answer 35

Fragile bones - easier to fracture

Question 36

Osteoporosis is…

Answer 36

The decrease in bone integrity due to an increased activity in osteoclast activity over osteoblast activity

Question 37

Osteoporosis treatments

Answer 37

Bisphosphonates - taken up by osteoclasts to undergo apoptosis

Question 38

Rickets is…

Answer 38

Poor osteoid mineralisation due to vitamin D deficiency- leads to distorted epiphyseal growth plates

Question 39

Osteomalacia is…

Answer 39

Vitamin D deficiency in adults leading to poorly mineralised osteoid and therefore easier fractures