Bone Histopathology Flashcards Preview

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Flashcards in Bone Histopathology Deck (65):
1

What do types of connective tissue have in common?

Made of connective cells with ECM in between

2

Where can we find hyaline cartilage?

ribs, trachea, joints

3

What type of collagen is found in hyaline cartilage?

type 2 collagen

4

What is the function of large GAGs in hyaline cartilage?

attract water and give the stiffness

5

What is the function of chondronectin

provide attachment for chondrocytes, as healthy cartilage require constant maintenance of chondrocytes

6

What are the characteristics of elastic cartilage?

mixture of hyaline cartilage and elastin
very flexible, maintains shape

7

Where can we find elastic cartilage?

the ear and tubular canals

8

What is fibrocartilage made of?

hyaline cartilage and fibrous tissue
Hybrid of connective tissue and isolated islands of chondrocytes

9

T/F Perichondrium can be found on fibrocartilage

False, it's only found in hyaline and elastic cartilages

10

T/F Fibrocartilage has type I collagen

True

11

T/F Fibrocartilage will replace the collagen type II centre in annulus fibrosis by the age of 20

False, AF is already made of fibrocartilage. The nucleus pulposus collagen type II will be replaced by fibrocartilage by 20

12

What are the two types of bone structure?

outer compact bone
inner trabecular bone

13

Where can we find Haversian systems? What are they?

compact bone. They are long columns of bone surrounding a central blood vessel. It lines parallel to lines of stress

14

How do osteocytes in the trabecular bone get access to nutrients

they extend out processes into the marrow cavity

15

Where can we find red marrow in an adult?

Flat bones

16

What are the two layers of connective tissue on the surface of bone? Which cells can be found there?

periosteum and endosteum
osteoprogenitor cells

17

What are Sharpey's fibres?

Tendon collagen penetrating bone surface, and type I collagen becomes continuous with bone collagen

18

Why is hyaline cartilage ideal for joint surface?

the cartilage is smooth and incompressible

19

Which part of the bone does the nutrient artery supply?

diaphysis

20

What is perichondrium?

a layer of dense irregular connective tissue that surrounds the cartilage of developing bone

21

T/F the periosteum covers the articular surface

False, hence there is a lack of blood supply + problem with repair of damage

22

What is the synovial space?

fluid filled space that has no epithelium, lined by synovial membrane, providing nutrients/lubricants for the joint

23

What is synovial fluid made of?

ultrafiltrate of blood + proteoglycan

24

What is the function of osteoprogenitor cell?

they are usually resting, but when active, they can give rise to new osteoblasts to grow and repair bone

25

What does the osteoblast make?

osteoid, an organic ECM of bone composed of collagen type I and proteins

26

What is the function of bone matrix protein?

allows the inorganic compounds to adhere on the bone surface

27

Where can we find osteocytes? What is the function of osteocyte?

deep in the bone, surrounded by bone
they synthesis material to keep bone healthy

28

T/F Osteocytes play a role in calcium homeostasis

True, they are capable of destroying local bone to free up Ca

29

How does an osteoclast cause bone resorption

Osteocyte seals itself to bone around the edge and secrete HCL and proteases to dissolve calcium phosphate

30

How do we measure osteoclast activity

measure tartrate-resistant acid phosphatase

31

How are osteoclasts derived?

from hemopoietic stem cells, related to macrophages

32

What are the two ways of developing bone? What are the processes involved?

intermembranous - directly form bone from mesenchyme
endochondral - cartilage model replaced by bone

33

Describe the process of replacing cartilage with bone

1) starting with a cartilage model, bone collar is deposited on the surface of diaphysis, denying blood supply, and inner cartilage degenerates, forming an inner cavity
2) blood vessels can invade the primary ossification centre
3) secondary centre forms at epiphysis, with separate blood supply
4) bone continues to grow only at the epiphyseal plates

34

T/F The growth of epiphyseal plate is symmetrical

False, the diaphysis side usually grows faster

35

What are the layers of growth plate?

distal normal hyaline cartilage
layer of dividing chondrocyte
layer of mature chondrocyte
layer of dying, hypertrophic chondrocyte
layer of degenerated chondrocyte and bone deposition

36

What is woven bone? How is it different to adult bone?

woven bone = new bone during development or repair. It is more cellular, has more collagen, and lacks Haversian systems

37

How does remodelling occur?

osteoclasts dig a cavity in response to stress on bone
blood vessels invade
endosteum is laid down, allowing entry of osteoblasts to lay layers of bone with collagen in alternating directions
Only a small space is left at the end for the blood vessel

38

What's the Haversian system also known as?

Osteon

39

How do woven and lamellar bones differ in terms of collagen

woven: collagen is everywhere. Hence it's made very quickly
lamellar: collagen laid down in the same direction

40

What is the lacunae and the canaliculae of an osteocyte?

lacunae - spot where the osteocyte is

canaliculae: network for sucking up blood and nutrients

41

What do osteocytes mainly respond to?

mechanotransduction, so bones can remodel under stress

42

How do osteoblasts look when they are 1) inactive 2) active

inactive: flat, like osteoprogenitors
active: big and plump, similar to plasma cells but don't have dotted nuclei

43

how are osteoclasts stimulated?

Indirectly by RANK-L and M-CSF from osteoblasts

44

Which molecule blocks the action of RANK ligand on an osteoblast

OPG

45

Why does osteoid (from osteoblasts) contain cytokines?

cytokines get laid down along with bone matrix, so osteoblasts can be stimulated where bone has been resorbed

46

What's the function of the substance inside the secretory vesicle from osteoblasts?

vesicles contain ALP, pyrophosphatase, and are used to increase local concentration of calcium and phosphate for precipitation

When concentration of mineral is high enough, they crystalise

47

What's the most common calcium phosphate?

hydroxyapatite

48

What's the difference between a greenstick fracture and a torus fracture

greenstick - incomplete fracture only on one side of cortex

torus - ring of cortical fracture, usually due to compression

49

T/F Oblique fracture heals faster than spiral fractures

False, spiral heals faster because there are numerous edges of bones in contact with each other

50

What's a comminuted fracture?

multiple fragments of fracture

51

What's a stress fracture caused by?

repeated low force injury to a normal bone

52

What's the composition of granulation tissue

fibroblast, collagen, capillaries

53

What's involved in the inflammatory phase of bone healing

How long does this phase last?

haematoma formation - fibrin mesh, platelet + leukocyte infiltration, granulation tissue formation

few days

54

What's the composition of soft callus in bone healthing

cartilage from condrocyte activation (hold the bone together) + periosteum on the outside

55

How is soft callus different to hard callus?

osteoid is deposited in hard callus. The ossification forms woven bone, and cartilaginous soft callus is broken down

56

What are the four phases of bone healing, and how long is each phase?

hematoma- few days
soft callus - days to weeks
hard callus - weeks to months
remodelling - months to years

57

What is the crucial factor in helping bone healing

stability

58

T/F Repairing of bone always undergo endochondral ossification

False, the healing method will depend on the amount of movement and pressure placed on the bone

59

What's a pseudo-arthrosis?

a non-union healing of fracture, where fibrous tissue is laid down, and the fracture will not heal

60

What is mal-union?

healing of a bone in an unacceptable position

61

What are some possible consequences of inappropriate healing of bone?

infection
osteonecrosis

62

What is osteoporosis?

reduced mass of otherwise normal bone, leading to increased risk of fracture

63

What is the difference between osteoporosis and osteomalacia

osteoporosis is a reduction in total bone cell count, whereas osteomalacia has demineralisation of bone and no loss of cells

64

What's Paget's disease

large, overactive osteoclasts, leading to overactive osteoblasts

"inappropriate remodelling"

65

What are some common sites of cancer that can give rise to bony metastasis

breast
bronchus
thyroid
kidney
prostate