Joints, Cartilage and Synovial Fluid Flashcards
structural classification of joints
fibrous
cartilagenous
synovial
give examples of fibrous joints
periodontal ligament
cranial sutures
interosseous membranes
name the two types of cartilaginous joints
primary - synchondrosis
secondary - symphysis
what type of cartilage is found in a primary cartilaginous joint?
hyaline cartilage
what type of cartilage is found in a secondary cartilaginous joint?
hyaline and fibrocartilage
give examples of secondary cartilaginous joint
midline - IV discs, pubic symphysis, manubriosternal
common features of synovial joints
cavity
articular cartilage
fibrous capsule
membrane
what other features of synovial joints may be there?
Articular disc
ligaments
bursae
what types of synovial joints are there?
plane/gliding condylar - ellipsoid hinge saddle pivot ball and socket
example of plane joint
IV discs
example of condylar hoint
metacarpophalangeal
example of hinge joint
elbow
knee
example of saddle joint
carpometacarpal of thumb
example of pivot joint
proximal and distal radioulnar
example of ball and socket joint
hip
shoulder
movements in a plane joint
1 plane
movements in a condylar joint
flexion extension adduction abduction circumduction
movements in a hinge joint
1 plane
movements in a pivot joint
1 plane
what factors maintain joint stability?
shape of the articulating surfaces
capsule
ligaments
muscles
describe hyaline cartilage: superficial layer
flattened chondrocytes that produce collagen and glycoproteins e.g.lubricin
describe hyaline cartilage: transitional layer
round chondrocytes that produce proteoglycans such as aggrecan
why is 75% of hyaline cartilage composed of water?
cannot be compressed
what are glycoproteins?
lubricin
to which oligosaccharide chains are attached
what are proteoglycans?
aggrecan
proteins that are heavily glycosylated
what is hyaluronic acid?
a glycosaminoglycan or GAG, is a long unbranched polysaccharide, which is highly polar and thus attracts water
average thickness of articular cartilage?
2-3 mm
why is healing of cartilage slow?
avascular
aneural
alymphatic
what produce synovial fluid?
synoviocytes
describe the synovial membrane and how this helps in function?
rich capillary network with no epithelial lining
allows for direct exchange of oxygen, carbon dioxide and metabolites between blood and synovial fluid
type A synoviocytes
look like macrophages and remove debris
contribute to synovial fluid production
type B synoviocytes
fibroblast like
main producers of synovial fluid
describe the components of synovial fluid
viscous fluid containing hyaluronic acid and lubricin
where does synovial fluid come from?
blood plasma
approx how much synovial fluid is there in the knee?
0.5ml
turnover of synovial fluid
2 hours
functions of synovial fluid
provide nutrient to the cartilage and remove waste products
lubricin
functions of glycoproteins in synovial fluid
bind to receptors on the articular surfaces to form a thin film which acts as a boundary for the fluid
describe the properties of synovial fluid
hydrodynamic
surfaces kept apart by liquid pressure
viscosity of the fluid changes with load and velocity of movement
what is weeping in regards to synovial fluid?
Fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume. This is known as weeping.
what are bursae and their functions?
synovial membranes filled with fluid to reduce friction
effect of ageing on synovial joints
As we age the viscosity of synovial fluid increases leading to slower joint movements and reduced lubrication. The water content of cartilage decreases therefore there is reduced shock absorption. This all leads to less protection of articular surfaces and increased risk of damage.
