joints, synovial fluid and cartilage

Question 1

types of joints

Answer 1

fibrous
cartilaginous
synovial

Question 2

examples of fibrous joints

Answer 2

cranial sutures
periodontal ligament
interosseus membranes

Question 3

primary cartilaginous joint

Answer 3

just hyaline cartilage

Question 4

secondary cartilaginous joint

Answer 4

hyaline and fibrocartilage

Question 5

types of synovial joint (6)

Answer 5

plane 
condylar 
hinge
saddle 
pivot
ball + socket

Question 6

what factors contribute to joint stability

Answer 6

• shape of articulating surfaces
• muscles
• capsules and ligaments

Question 7

types of cartilage in synovial joints

Answer 7

hyaline (articular)

fibrocartilage

Question 8

superficial layer of articular cartilage

Answer 8

flattened chondrocytes that produce collagen + glycoproteins (e.g. lubricin)

Question 9

transitional layer of articular cartilage

Answer 9

round chondrocytes that produce proteoglycans (e.g. aggrecan)

Question 10

glycoproteins e.g. lubricin

Answer 10

proteins to which oligosaccharide chains are attached

i.e. more a protein than a carbohydrate

Question 11

proteoglycans e.g. aggrecan

Answer 11

proteins that are heavily glycosylated (protein core to which 1+ GAGs are attached)
i.e. more carbohydrate than protein

Question 12

glycosaminoglycans (GAGs) e.g. hyaluronic acid

Answer 12

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

Question 13

cartilage properties

Answer 13

avascular
aneural
alymphatic

Question 14

does synovium have an epithelial lining

Answer 14

no, there is direct exchange of O2, CO2 and metabolites between blood and synovial fluid

Question 15

what produces synovial fluid

Answer 15

synoviocytes

Question 16

type a synoviocyte

Answer 16

look like macrophage
remove debris
contribute to synovial fluid production

Question 17

type b synoviocyte

Answer 17

fibroblast like

main producer of synovial fluid

Question 18

functions of synovial fluid

Answer 18

nutrition of articular cartilage
removal of waste products
lubrication –> less friction –> less wear

Question 19

how are joints lubricated

Answer 19

• Boundary: glycoproteins bins to receptors on articular surfaces to form a thick film
• Hydrodynamic: surfaces kept apart by liquid pressure, viscosity changes with load + velocity of movement
• weeping: fluid present in cartilage is squeezed out into synovial cavity to increase fluid volue

Question 20

what are bursae

Answer 20

small sac-like cavities that contain fluid and are lined by synovial membrane
located subcutaneously between bony prominences or tendons
facilitate movement with reduced friction

Question 21

changes with ageing

Answer 21

viscosity of synovial fluid increases –> slower joint movements + reduced lubrication
decreased cartilage water content –> reduced shock absoption