Joints and Synovial fluid and cartilage

Question 1

What are the 3 types of joints

Answer 1

Fibrous
Cartilaginous
Synovial

Question 2

Where may you find fibrous joints

Answer 2

Periodontal ligament
cranial sutures
Interosseus membranes

Question 3

A primary Cartilaginous joint contains

Answer 3

only hyaline cartilage

Question 4

A secondary Cartilaginous joint contains

Answer 4

hyaline & fibrocartilage

Question 5

Symphysis is

Answer 5

Secondary cartilaginous

Question 6

Synchondrosis is

Answer 6

Synchondrosis (Primary cartilaginous)

Question 7

Common features of synovial joints

Answer 7

Articular discs
Ligaments
Bursae
Fibrous capsule 
Synovial fluid filled cavity
articular cartilage

Question 8

Different types of synovial joints

Answer 8

plane
hinge
pivot
condylar 
saddle
ball and socket

Question 9

Joint stability is due to

Answer 9

Shape of articulating surfaces
Capsule & ligaments
Muscles

Question 10

Cartilage found in synovial joints

Answer 10

Hyaline and fibrocartilage

Question 11

Articular cartilage: Superficial/tangenital layer contains

Answer 11

flattened chondrocytes that produce collagen and glycoproteins (e.g. lubricin

Question 12

Articular cartilage: Transitional layer contains

Answer 12

round chondrocytes that produce proteoglycans such as aggrecan

Question 13

How much Articular cartilage is water

Answer 13

75%

Question 14

What are Glycoproteins (e.g. lubricin):

Answer 14

proteins to which oligosaccharide chains are attached, i.e. more a protein than a carbohydrate!

Question 15

What are Proteoglycans (e.g. aggrecan

Answer 15

): proteins that are heavily glycosylated (= a protein core to which one or more GAGs attach), i.e. tend to be more carb than protein!

Question 16

What are Glycosaminoglycans or GAGs (e.g. hyaluronic acid

Answer 16

long unbranched polysaccharides, which are highly polar and thus attract water

Question 17

Articular cartilage features

Answer 17

Cartilage thickness & forces
average: 2-3 mm
interphalangeal joint: 1 mm
patella: 5-6 mm

Question 18

Where is synovial fluid produced

Answer 18

synovial membrane (synovium)

Question 19

The 3 A’s of cartilage

Answer 19

Avascular
Aneural
Alymphatic

Question 20

Features of the synovium

Answer 20

Synoviocytes producing the fluid
Rich capillary network
No epithelial lining

Direct exchange of oxygen, carbon dioxide & metabolites between blood & synovial fluid

Question 21

Synoviocytes Type A vs B

Answer 21

Type A
Look like macrophages
Remove debris
Contribute to synovial fluid production

Type B
Fibroblast like
Main producer of synovial fluid

Question 22

Synovial fluid: contains?

Answer 22

Viscous fluid
Hyaluronic acid & lubricin
Fluid component (from blood plasma)

Small volumes (knee joint:   ̴0.5 ml )
Rapid turnover (  ̴2 hours)

Question 23

Functions of synovial fluid (3)

Answer 23

Nutrition of cartilage (articular c., menisci/discs)
Removal of waste products
Lubrication  less friction  less wear

Question 24

Lubrication - boundary

Answer 24

Glycoproteins such as lubricin bind to receptors on articular surfaces to form a thin film

Question 25

lubrication - Hydrodynamic (like aquaplaning)

Answer 25

Surfaces kept apart by liquid pressure

Viscosity changes with load and velocity of movement

Question 26

Lubrication - Weeping

Answer 26

Fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume

Question 27

Features of bursar

Answer 27

Synovial membrane
Fluid-filled
Reduce friction
Bursitis

Question 28

When we age what happens to synovial fluid

Answer 28

Viscosity of synovial fluid increases
Slower joint movements
Reduced lubrication
Water content of cartilage decreases
Reduced shock absorption

Less protection of articular surfaces & increased risk of damage

Question 29

Features of an osteoarthritic disk

Answer 29

Bone spur

Narrowed disk