lecture 15 - bone histology

Question 1

What is a lacuna?

Answer 1

A space containing a cell

Question 2

What is the outer layer of a bone called?

Answer 2

The periosteum

Question 3

What parts of a bone is absent of periosteum?

Answer 3

Articular surface, points of insertion of tendons/ligaments

Question 4

What is the periosteum made up of?

Answer 4

Condensed collagen

Question 5

What layer lines the inner surface of the bony wall?

Answer 5

Endosteum

Question 6

What is the endosteum?

Answer 6

The layer lining the inside of bones, containing bone cells

Question 7

What types of cells does the endosteum contain?

Answer 7

Osteoprogenitor cells, osteoblasts, osteoclasts

Question 8

What is stored in the medullary cavity?

Answer 8

Hemopoietic tissue (marrow), fat

Question 9

What is the long shaft of a long bone called?

Answer 9

Diaphysis

Question 10

What are the ends of a long bone called?

Answer 10

Epiphysis

Question 11

What separates the epihysis and diaphysis of a long bone?

Answer 11

Metaphysis

Question 12

What are the 2 types of bone?

Answer 12

Compact, trabecular/cancellous

Question 13

What is the function of compact bone?

Answer 13

Strength/rigidity, resist tensile forces

Question 14

What is the function of cancellous bone?

Answer 14

Minimising bone weight while resisting compressive forces

Question 15

What is the alternative name for osteons?

Answer 15

Haversian systems

Question 16

What are osteons?

Answer 16

Bony tubes that lie parallel to each other along the long axis in compact bone

Question 17

What are the layers of an osteon called?

Answer 17

Lamellae

Question 18

What are lamellae made up of?

Answer 18

layers of ossified extracellular matrix

Question 19

What are the 3 types of lamellae in bone?

Answer 19

Concentric, Interstitial, circumferential

Question 20

Where are concentric lamellae found?

Answer 20

In layers around the osteons

Question 21

Where are circumferential lamellae found?

Answer 21

The periphery of bone

Question 22

Where are interstitial lamellae found?

Answer 22

Between haversian systems/osteons

Question 23

What are Haversian canals?

Answer 23

Canals that are parallel with the length of an osteon that carry blodo vessels and nerve axons.

Question 24

What is the contents of a Haversian Canal?

Answer 24

1 or 2 capillaries lined by fenestrated epithelium, and a few unmyelinated axons

Question 25

What is the nature of capillaries within Haversian canals?

Answer 25

Fenestrated

Question 26

What canals connect Haversian canals with each other?

Answer 26

Volkmann’s canals

Question 27

What is contained within each lacunae in an osteon?

Answer 27

An osteocyte

Question 28

What connects lacunae in an osteon?

Answer 28

Canaliculi

Question 29

How are nutrients brought to trabecular bone without blood vessels>?

Answer 29

Via canalicular diffusion from marrow vessels

Question 30

What connects the periosteum to the underlying cortical bone?

Answer 30

Sharpey’s fibres

Question 31

What are Sharpey’s fibres?

Answer 31

Fibres that connect underlying cortical bone to the periosteum

Question 32

Why is the periosteum important in fracture healing?

Answer 32

Contains osteoblasts and osteoprogenitor cells that are new-bone forming for remodelling/repair

Question 33

What does the endosteum line?

Answer 33

Medullary cavity, haversian canals, trabecular bone

Question 34

What cell types are found in the endosteum?

Answer 34

osteoblasts, osteoclasts, osteocytes

Question 35

What are the 2 key components of bone extracellular matrix?

Answer 35

collagen, hydroxyapatite microcrystals

Question 36

What are the biggest type of bone cell viewed histologically?

Answer 36

Osteoclasts

Question 37

What are the histological features of an osteoclast?

Answer 37

Large, lots of nuclei, folded plasma membrane

Question 38

What is the function of osteoclasts?

Answer 38

Break down bone matrix

Question 39

Where in bone are osteoclasts and osteoblasts found?

Answer 39

Lining the endosteum

Question 40

How can osteoblasts be identified histologically?

Answer 40

The line the endosteum

Question 41

What is the conditon caused by low osteoclast activity?

Answer 41

Osteopetrosis/marble bone disease

Question 42

What is the function of osteoblasts?

Answer 42

Synthesis, deposition and mineralisation of bone matrix

Question 43

What is the shape of osteoblasts?

Answer 43

Cuboidal

Question 44

How do osteoblasts connect with neighbouring osteoblasts?

Answer 44

Via plasma membrane extensions

Question 45

What is the shape of osteocytes?

Answer 45

Ellipsoid

Question 46

What feature of osteocytes help them form gap junctions with neighbouring cells via canaliculi?

Answer 46

Branching processes

Question 47

Where do osteoclasts sit?

Answer 47

In resoprtion bays - Howship’s lacunae

Question 48

What is intramembranous bone ossification?

Answer 48

Direct formation of bones from mesenchymal stem cells that develop into osteoprogenitor cells

Question 49

What is endochondral ossification?

Answer 49

The conversion of a hyaline cartilage model into bone

Question 50

What are the 2 types of bone formation/ossification?

Answer 50

Intramembranous ossification, endochondral ossification

Question 51

Where in a hyaline model does endochondral ossification begin?

Answer 51

A primary ossification centre

Question 52

Where is the primary ossification centre in a developing bone?

Answer 52

The middle - diaphysis

Question 53

Where are the secondary ossification centres in developing bone?

Answer 53

The ends / epiphyses

Question 54

What vessel supplies the periosteum?

Answer 54

Periosteal artery

Question 55

What vessel supplies the diaphysis of a long bone?

Answer 55

A diaphysial artery

Question 56

What vessel supplies the epiphysis of a long bone?

Answer 56

Epiphyseal artery

Question 57

What are the histological features of the synovial membrane?

Answer 57

surface with folds/villi, double layered

Question 58

What are the 2 layers of the synovial membrane?

Answer 58

Intimal layer, sub-intimal layer

Question 59

What makes up the intimal layer of the synovial membrane?

Answer 59

A discontinuous layer of synovial cells

Question 60

What makes up the subintimal layer of the synovial membrane?

Answer 60

Connective tissue with collage/elastin fibres, fibroblasts, macrophages