Joints and Synovial fluid and cartilage Flashcards
What are the 3 types of joints
Fibrous
Cartilaginous
Synovial
Where may you find fibrous joints
Periodontal ligament
cranial sutures
Interosseus membranes
A primary Cartilaginous joint contains
only hyaline cartilage
A secondary Cartilaginous joint contains
hyaline & fibrocartilage
Symphysis is
Secondary cartilaginous
Synchondrosis is
Synchondrosis (Primary cartilaginous)
Common features of synovial joints
Articular discs Ligaments Bursae Fibrous capsule Synovial fluid filled cavity articular cartilage
Different types of synovial joints
plane hinge pivot condylar saddle ball and socket
Joint stability is due to
Shape of articulating surfaces
Capsule & ligaments
Muscles
Cartilage found in synovial joints
Hyaline and fibrocartilage
Articular cartilage: Superficial/tangenital layer contains
flattened chondrocytes that produce collagen and glycoproteins (e.g. lubricin
Articular cartilage: Transitional layer contains
round chondrocytes that produce proteoglycans such as aggrecan
How much Articular cartilage is water
75%
What are Glycoproteins (e.g. lubricin):
proteins to which oligosaccharide chains are attached, i.e. more a protein than a carbohydrate!
What are Proteoglycans (e.g. aggrecan
): proteins that are heavily glycosylated (= a protein core to which one or more GAGs attach), i.e. tend to be more carb than protein!
What are Glycosaminoglycans or GAGs (e.g. hyaluronic acid
long unbranched polysaccharides, which are highly polar and thus attract water
Articular cartilage features
Cartilage thickness & forces
average: 2-3 mm
interphalangeal joint: 1 mm
patella: 5-6 mm
Where is synovial fluid produced
synovial membrane (synovium)
The 3 A’s of cartilage
Avascular
Aneural
Alymphatic
Features of the synovium
Synoviocytes producing the fluid
Rich capillary network
No epithelial lining
Direct exchange of oxygen, carbon dioxide & metabolites between blood & synovial fluid
Synoviocytes Type A vs B
Type A
Look like macrophages
Remove debris
Contribute to synovial fluid production
Type B
Fibroblast like
Main producer of synovial fluid
Synovial fluid: contains?
Viscous fluid
Hyaluronic acid & lubricin
Fluid component (from blood plasma)
Small volumes (knee joint: ̴0.5 ml ) Rapid turnover ( ̴2 hours)
Functions of synovial fluid (3)
Nutrition of cartilage (articular c., menisci/discs)
Removal of waste products
Lubrication less friction less wear
Lubrication - boundary
Glycoproteins such as lubricin bind to receptors on articular surfaces to form a thin film
lubrication - Hydrodynamic (like aquaplaning)
Surfaces kept apart by liquid pressure
Viscosity changes with load and velocity of movement
Lubrication - Weeping
Fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume
Features of bursar
Synovial membrane
Fluid-filled
Reduce friction
Bursitis
When we age what happens to synovial fluid
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
Features of an osteoarthritic disk
Bone spur
Narrowed disk
