3: Joints, Synovial Fluid and Cartilage Flashcards
what is the difference between a primary and secondary cartilaginous joint?
give an example of each
- primary: only hyaline cartilage e.g. synchondrosis in growth plates
- secondary: hyaline and fibrocartliage e.g. symphysis in intervertebral discs
list some attributes of articular cartilage in synovial joint
- high water content
- impermeable
- strong under compression
what are glycosaminoglycans or GAGs?
unbranched polysaccharides
highly polar > attract water
what are glycoproteins?
proteins with carbs attaches
what are proteoglycans?
- subclass of glycoproteins
- proteins with GAGs attaches (tend to be more carb than protein)
describe the compostition of articular (hyaline) cartilage
go through layers
what is the average thickness of articular cartilage?
2-3mm
how thick is the cartilage in the interphalangeal joint?
1mm
how thick is the cartilage of the patella?
5-6mm
describe the synovium
- synovial membrane that contains synoviocytes which produce synovial fluid.
- rich capillarly network.
- no epithelial lining.
- direct exchange of oxygen, carbon dioxide and metabolites between blood and synovial fluid.
what is the difference between type A and B synoviocytes?
Type A:
- look like macrophages
- remove debris
- contribute to synovial fluid production
Type B:
- fibroblast-like
- main producer of synovial fluid
describe synovial fluid and its components
- viscous fluid
- hyaluronic acid & lubricin
- fluid component (from blood plasma)
- rapid 2hr turnover
what are the 3 mechanisms of lubrication?
fluid film:
- surfaces kept completely apart by fluid
- much of the load born by the pressurised fluid
weeping:
- interstitial fluid is squeezed out of the cartilage into the synovial cavity to increase fluid volume
boundary:
- contact between surfaces, but coated with bio-lubricants
