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Flashcards in Cartilage and Bone Deck (72):
0

Is cartilage vascular or avascular

-Avascular

1

In general, what two components make up cartilage?

-Chondrocytes
-Extensive ECM

2

What is the function of the chondrocytes within cartilage?

-To produce and maintain ECM

3

What is the ECM of cartilage made up of?

-Hyaluronic acid and proteoglycan aggregates
-Proteoglycan monomers have a core protein with gags attached
-Collagen fibres

4

What are the characteristic features of cartilage?

-Resilience to repeated applied pressure
-Non-compressibility
-Solid but pliable
-Elasticity

5

What does the gag:collagen ratio of the ECM ensure?

-The ratio permits diffusion of nutrients to the chondrocytes from the surrounding blood vessels

6

Which type of collagen is predominantly found in cartilage?

-Type 2

7

What type of tissue is cartilage?

-Connective tissue

8

Name the three type os cartilage

-Hyaline
-Elastic
-Fibrocartilage

9

What is the ECM of hyaline cartilage made of?

-Hyaluronic acid and proteoglycan aggregates bound to type II collagen
-Proteoglycan monomers have a core protein with gags attached

10

What is the main characteristic feature of hyaline cartilage?

-Resilience to repeated pressure loads

11

What occurs when pressure loads are applied to hyaline cartilage?

-Creates mechanical, electrical and chemical signals which direct the synthetic activity of the chondrocytes

12

What cell type is found in hyaline cartilage?

-Chondrocytes

13

Where in the body is hyaline cartilage found?

-larynx, trachea, bronchus
-ear and nose
-ribs
-articulating surfaces of joints
-At the epiphyseal growth plate

14

What surrounds cartilage?

-Perichondrium

15

What is particular about the hyaline cartilage at articulating surfaces of joints?

-No perichondrium as would be damaged, needs to be smooth and thus cannot repair itself, gets nutrients from surrounding fluid
-Also contains type III collagen

16

Why does hyaline cartilage at articulating surfaces have irregular boundaries?

-To prevent shearing off

17

Describe how chondrocytes are distributed in hyaline cartilage

-Lie in lacunae, separated by ECM that they secrete or in isogenous groups if just recently divided, which eventually become to lie separately

18

Why does hyaline cartilage remain at the epiphyseal growth plates?

-To allow elongation of long bones

19

What is interstitial growth in cartilage?

-Growth which occurs as a result of isogenous groups secreting matrix and becoming single cells laying in separate lacuna

20

What is appositional growth?

-Growth from the periphery
-The perichondrium contains elongate fibroblast-like cells which develop into chondroblasts and then into chondrocytes, laying down ground substance as they develop

21

What is the territorial matrix?

-The highly sulphated deeply staining matrix immediately surrounding chondrocytes

22

What is the interterritorial matrix?

-The matrix which lies in between chondrocytes and their lacunas

23

How is the ECM of elastic cartilage similar/different from that of hyaline cartilage, and what extra feature does this add?

-ECM made of hyaluronic acid and protein aggregates providing resilience
-Contains many elastic fibres conferring elasticity upon the cartilage

24

What colour is elastic cartilage in FRESH tissue?

-Yellowish

25

Where is elastic cartilage found in the body?

-Pinna of the ear
-Eustachian tube
-Epiglottis
-Auditory meatus

26

Does hyaline cartilage or elastic cartilage have more abundant chondrocytes?

-Elastic

27

What cell type(s) does fibrocartilage contain?

-Chondrocytes and fibroblasts (in relatively low numbers)

28

Why is fibrocartilage different from hyaline and elastic cartilage?

-It is a mixture of dense irregular connective tissue and hyaline cartilage

29

Does fibrocartilage have a surrounding perichondrium?

-No

30

Describe the distribution of cells within fibrocartilge

-Often found in rows or isogenous groups
-Few

31

What fibres does fibrocartilage contain?

-TI and TII collagen

32

How are the fibres arranged in fibrocartilage? Relate the structure to its function

-Fibres run in parallel with direction of force exerted upon it
-Provides high tensile strength and non-compressibility

33

What is the main function of fibrocartilage?

-Shock absorber and resistance of shearing force

34

Where is fibrocartilage located in the body?

-Intervertebral discs
-Sternoclavicular and temperomandibular joints
-Menisci of the knee joing
-Pubic Synthesis
-Ethesis

35

What is ethesis?

-Point of attachment of tendon to bone

36

Which type of cartilage calcifies with age?

-Hyaline

37

Which cartilage is the most common?

-Hyaline

38

In general, what are the three constituents of bone?

-Cells
-ECM
-Fibres

39

What is specific about the ECM of bone?

-Integrated with mineral salts, particularly calcium phosphate for rigidity and hardness

40

How is bone specialised for its function?

-High mechanical strength with minimal weight

41

Name the different groups of bones

-Long bones
-Short bones
-Flat bones
-Sesamoid bones

42

What are the two types of bone?

-Compact
-Spongy (Cancellous/trabecular)

43

What is the macroscopic histiological appearance of compact bone?

-Dense bone with no cavities

44

Where is compact bone found?

-External surfaces of bones

45

Microscopically, into what is compact bone arranged?

-Into osteons

46

What are osteons?

-Concentric lamellae of bone arranged around a central haversian canal, joined to other osteons, periosteum and bone marrow by volkmann canals

47

What do haversian canals carry?

-Blood vessels, lymphatics and nerves

48

What is cementing substance?

-A thin homogenous layer of amorphous material between osteons

49

Are volkmann canals surrounded by concentric lamellae?

-No

50

What are interstitial lamellae?

-Remnants of lamellae which used to be concentrically arranged around an osteon have been remodelled

51

What is the macroscopic structure of cancellous bone?

-Interconnecting network of cavities, filled with bone marrow separated by numerous irregular trabeculae

52

What is the microscopic structure of trabeculae?

-No haversian systems
-Lamellae not arranged in concentric circles but irregularly

53

How does trabecular bone receive nutrients?

-By diffusion from the marrow

54

What is periosteum?

-Vascular connective tissue which surrounds bone

55

What cell types are found in bone?

-Osteoblasts (which develop into osteocytes)
-Osteoclasts

56

What is the function of osteoblasts?

-Lay down new osteiod in bone remodelling

57

What is the function of osteoclasts?

-To resorb bone during bone remodelling

58

How do osteoclasts exert their action?

-Through H+ and lysosomal enzymes

59

In what do osteocytes lie?

-Lacunae

60

How are osteocytes arranged in immature and mature bone?

-Immature-> fairly randomly arranged
-Mature-> in the concentric lamellae

61

What is different about the lacunae of bone to lacunae of cartilage?

-Radiate canaliculi which anastomose with canaliculi of other lacunae

62

What is the function of canaliculi?

-Permit osteocyte cytoplasmic processes and passage of ions and nutrients to those osteocytes which lay far away from the artery

63

What is the sheath of neumann?

-fine fibrous tissue which lines lacunae and canaliculi

64

What must happen to bone in order for it to be histologically viewed?

-Decalcified which kills organic material
or
-Ground

65

Describe the action of bone remodelling

-Osteoclasts resorb bone through H+ and lysosomal enzymes which forms a cutting cone which runs parallel to the direction of the haversian canal creating a resorption cavity, osteoclasts lie in the resulting depression
-Osteoblasts deposit osteoid in sucessive lamellae creating a closing cone, filling the resorption cavity with new bone

66

Why can the bone resist fracture until a certain point?

-High tensile strength
-Degree of flexibility- lamellae can slip relative to one another before excessive force causes fracture

67

What are the four stages of bone repair following a fracture?

-Haematoma formation
-Fracture repair
-Bony callus formation
-Bone remodelling

68

Describe haematoma formation following a fracture

-Blood vessels in bone and periosteum break
-Haematoma (mass of clotted blood) forms
-Cells at periphery of fracture die due to lack of blood supply
-Removed by macrophages

69

Describe fracture repair following haematoma in a bone fracture

-New blood vessels infiltrate haematoma
-Procallus of granulation tissue (tissue rich in fibroblasts and capillaries) forms
-Fibroblasts produce collagen fibres which span the break, others differentiate into chrondrocytes and form a sleeve of hyaline cartilage across the break
-An externally buldging fibrocartilagineous matrix splints the bone

70

Describe bony callus formation after procallus formation following a fracture

-Trabeculae develop and a spongy callus is formed
-Edochondral ossification replaces cartilage with bone
-Fibrocartilagineous callus is know a hard bony callus of cancellous bone
-Continues for 2 months until hard union is formed

71

Describe bone remodelling following a fracture

-Spongy bone remodelled to compact bone at cortical regions
-Osteoclasts remove externall budlging bone and bone protruding into medullary cavity
-Final shape will be the same as the original bone as remodelling will be in response to the same mechanical stressors