Joints, Synovial Fluid and Cartilage Flashcards
What are the three types of joints?
Fibrous, Cartilaginous and Synovial
Where can fibrous joints be found?
The skull, periodontal ligaments, interosseus membranes
Where can cartilaginous joints be found?
Growth Plates (synchondrosis aka primary cartilaginous joints - only hyaline)
Intervertebral Discs (Symphysis joint aka secondary cartilaginous - hyaline and fibrocartilage)
What are the features of synovial joints?
- Synovial cavity, articular cartilage, fibrous capsule, synovial membrane
What are the types of synovial joints?
Plane, Condylar, Hinge, Saddle, Pivot, Ball and Socket
What influences joint stability?
Shape of articulating surfaces, capsule and ligaments, muscles
What are the types of cartilage within a synovial joint?
Hyaline and Fibrocartilage
Describe the histology of hyaline cartilage?
Superficial layer - flattened chondrocytes that produce collagens and glycoproteins
Transitional Layer - round chondrocytes that produce proteoglycans
What are glycoproteins ?
Proteins to which oligosaccharide chains are attached
What are proteoglycans ?
Proteins that are heavy glycosylated
What are glycosaminoglycans?
Long unbranched polysaccharides which are highly polar and thus attract water
What is the average thickness of hyaline cartilage?
Average :2-3mm
Interphalangeal Joint -1mm
Patella - 5-6mm
What is synovial fluid produced by?
Synoviocytes within synovium
What occurs at synovium?
Direct exchange of oxygen, carbon dioxide and metabolites between blood and synovial fluid
Describe Type A synoviocytes?
Look like macrophages, remove debris, contributes to synovial fluid production
Describe Type B synoviocytes?
Fibroblast like and main producer of synovial fluid
Describe synovial fluid?
Viscous fluid containing hyaluronic acid and lubricin
What is the function of synovial fluid?
Nutrition of cartilage, removal of waste products
Lubrication = less friction and less wear
Describe the process of lubrication?
Boundary
- glycoproteins bind to receptors on articular surfaces to form a thin film
Hydrodynamic
- Surfaces are kept apart by liquid pressure
- Viscosity changes with load and velocity of movement
Weeping
- Fluid that is present in the cartilage is squeezed out into synovial cavity to increase fluid volume
What are bursae?
Fluid filled sacs which reduce friction
What occurs to synovial fluid and cartilage with ageing?
Increased viscosity of synovial fluid = slower joint movements, reduced lubrication
Water content of cartilage decreases and reduces shock absorption
