AP02 - bones and cartilage

Question 1

Name 3 types of cartilage

Answer 1

hyaline
elastic
fibrous

Question 2

Where is hyaline cartilage roughly found?

Answer 2

lining articular surfaces of synovial joints (other than TMJ)

Question 3

What is the TMJ and what cartilage does it use?

Answer 3

temporomandicular joint

fibrocartilage

Question 4

What does cartilage ECm typically have>

Answer 4

collagen

proteoglycans (like aggrecan)

Question 5

What does the ground substance of hyaline cartilage contain?

What is the function of this substance?

Answer 5

glycosaminoglycans (3 types):
hyaluronic acid
chondroitin sulphate
keratin sulphate

traps water - frictionless

Question 6

Why is hyaine cartilage particularly strong?

Answer 6

collagen (II)

Question 7

What cartilage group does articular cartilage belong to?

Answer 7

hyaline cartilage

Question 8

What are the layers to articular cartilage?

Answer 8

tangenital layer (collagen parallel to bone surface)
transitional zone (large chondrocytes)
radial layer (cartilage is partially calcified)

Question 9

How well is cartilage vascularised?

Why is this significant?

Answer 9

not!

dependent on diffusion through hydrated matrix for survival - metabolites originate from the synovial fluid

Question 10

What two processes dictate cartilage tissue turnover?

Answer 10

anabolism

catabolism

Question 11

How might cartilage anabolism be affected by stress or disuse?

Answer 11

stress - anabolic activity can’t keep up

disuse - inhibits anabolism, net degeneration

Question 12

What is the first stage in development of OA?

Answer 12

changes in articular cartilagelimit ability to withstand compressive forces
stressed chondrocyts release tissue breakdown particles

Question 13

What is the second stage of OA development

Answer 13

necrosed tissue is surrounded by focal clumps of proliferating cartilage
surviving chondrocytes attempt to repair lesion

Question 14

What is the third stage of OA development

Answer 14

Once the bone is exposed, microfractures of the trabeculae occur

Question 15

What is the fourth stage of OA development

Answer 15

osteoblasts respond by forming new bone, where other areas become necrosed
degeneration and regeneration cycle limits strength

Question 16

Give 3 general functions of bone

Answer 16

mechanical support
calcium homeostasis
haematopoiesis

Question 17

What is periosteum?

Answer 17

2 fibro-collagenous membranes, with osteoblasts (for proliferatio)
Covers the whole bone other than bits with cartilage

Question 18

What do osteoblasts make, and where?

What else might this structure be called?

Answer 18

osteons, which surround central canals with neurovasculature and osteoblasts

Haversian system

Question 19

What is the structure of marrow bone?

What happens to marrow bone over time?

Answer 19

spaces with haematopoietic cells (red) or fat (white)

over time, the bone gets more fatty

Question 20

Cortical bone:
location
functino
periosteum
tissue turnover
blood supply

Answer 20

diaphysis of long bones
structural support
thick
slow
sparse

Question 21

Cancellous bone:
locatin
funcion
periosteum
tissue turnover
blood supply

Answer 21

metaphyseal or marrow bone, in tarsals and carpals, diploe of flat bones

metabolic function
thin
rapid
rich

Question 22

What is the diaphysis?

Answer 22

shaft of long bone, doesn’t cope well with torque

Question 23

define Epiphysis

Answer 23

growth plate - mitotically dividing cartilage

capable of hypertrophy

Question 24

define metaphysis

Answer 24

widening aspect between diaphysis and epiphysis

Question 25

define epicondyle

Answer 25

profection close to the condyle for ligament and tendon attachment

Question 26

What is woven bone?

Answer 26

irregular bone in developing and growing bones, or in healing fractures It is remodelled into lamellar bone

Question 27

What is the structure of an osteon?

Answer 27

osteocytic lacunae occur with canaliculi radiating through the lamellae, facilitating intercellular communication

Question 28

How does intramembranous ossification occur?

Answer 28

osteoblasts differentiate directly form mesenchyme and begin secreting osteoid - forms flat bones

Question 29

How does endochondral ossification occur?

Answer 29

pre-existing matric of hyaline caratilage is eroded and invaaded by osteoblasts, which then beigin osteoid production

Question 30

Define synarthrosis

Answer 30

a rigid cartilaginous join between two bones

Question 31

Define synostisis

Answer 31

fused bones - immovable

Question 32

How might collagen fibres be arranged to offer greater stability?

Answer 32

concentric rings, weightbearing along a greater axis

Question 33

What type of ossification are flat bones formed by?

Answer 33

intramembranous ossification

Question 34

What happens to chondrocytes over their lifetime?

Answer 34

proliferate away from the blood, so they eventually stop mitosis and grow they then calcify and die