Joints, Synovial Fluid and Cartilage Flashcards
Name the three structural classifications of joints?
- Fibrous
- Cartilaginous
- Synovial
Give three examples of fibrous joints
- Cranial sutures
- Periodontal ligament
- Interosseus membranes
Give the two types of cartilaginous joints and the difference between them
- Primary:/Synchondrosis only contains hyaline cartilage
- Secondary/Symphysis: contains hyaline and fibrocartilage
Give examples of where cartilaginous joints are found
- Primary: Epiphyseal growth plate
- Secondary: Intervertebral disc
What are the common features of synovial joint?
- Synovial cavity (fluid-filled)
- Articular cartilage
- Fibrous capsule
- Synovial membrane
- May also contain: articular discs, ligaments and bursae
Name the common types of synovial joints
- Plane
- Hinge
- Pivot
- Condylar
- Saddle
- Ball and Socket
Which factors contribute to joint stability?
- Shape of articulating surfaces
- Capsules and ligaments
- Muscles
Name the features of Articular (hyaline) cartilage
- Superficial layer: contains flattened chondrocytes that produce collagen and glycoproteins
- Transitional layer: contains round chondrocytes that produce proteoglycans
- Changes in collagen orientation from superficial to deep
- > 75% water (incompressible)
What are glycoproteins?
Proteins to which oligosaccharide chains are attached e.g. lubricin
What are proteoglycans?
Proteins that are heavily glycosylated e.g. aggrecan
What are glycosaminoglycans (GAGs)?
Long unbranched polysaccharides, which are highly polar and thus attract water e.g. hyaluronic acid
Which structures does cartilage not contain?
- Blood vessels
- Nerves
- Lymphatics
Which structure produces synovial fluid?
Synovial membrane - synoviocytes
How do oxygen, CO2 and metabolites reach the synovium?
Direct exchange between blood and the synovial fluid
What are the two types of synoviocytes and how do they differ?
- Type A: look like macrophages, remove debris and contribute to synovial fluid production
- Type B: like fibroblasts and are the main producers of synovial fluid
What are the main components of synovial fluid?
- Viscous fluid
- Contains hyaluronic acid and lubricin
- Fluid component from plasma
- Small volumes
- Rapid turnover
What are the functions of synovial fluid?
- Nutrition of cartilage
- Removal of waste products
- Lubrication
What are the three mechanisms of lubrication of joints?
- Boundary: glycoproteins bind to receptors on articular surfaces to form a thin film
- Hydrodynamic: surfaces are kept apart by liquid pressure
- Weeping: fluid present in the cartilage is squeezed into the synovial cartilage to increase fluid volume
What are bursae and what is their function?
- Fluid filled sacs in the joint
- Reduce friction
What happens to the joints as part of the ageing process?
- Viscosity of the synovial fluid increases (slower movements and reduced lubrication)
- Water content of cartilage decreases (reduced shock absorption)
- Less protection of articular surfaces and increased risk of damage
