Physiology: joints Flashcards
what are the different types of joints
synovial, fibrous and cartilaginous
briefly describe a fibrous joint(synarthrosis) and give an example
bones united by fibrous tissue
example = between bones of skull in adults
what movement do fibrous joints allow
no movement
briefly describe a cartilaginous joint(amphiarthrosis) and give an example
bones united by cartilage
example = intervertebral discs
briefly describe a synovial joint(diarthrosis) and give an example
bones separated by a cavity and united by a fibrous capsule, and extra-articular structures
example = knee joint
what does the cavity in synovial joints contain
synovial fluid
describe what the synovial membrane is, and where it is found
vascular connective tissue with capillaries and lymphatics, found in inner aspect of fibrous capsule
describe the function of the synovial membrane
contains synovial cells(fibroblasts) that produce synovial fluid
what are the articular surfaces of bones covered with in synovial joints
articular(hyaline) cartilage
what different types can synovial joints be classified into
simple = one pair of articular surfaces compound = more than one pair of articular surfaces
what extra-articular structures are synovial joints supported by
bursa, ligaments, tendons
what are the physiological functions of joints
structural support and purposeful motion
describe the roles of joints in purposeful motion
stress distribution, confer stability, joint lubrication
what is joint lubrication provided by
synovium-derived hyaluronic acid, synovium-derived lubricin and cartilage interstitial fluid
describe the functions of synovial fluid
lubricates joint, facilitates movement, helps minimise wear-and-tear, nutrition of articular cartilage
what are chondrocytes
cartilage cells
what does synovial fluid supply chondrocytes with and remove
supplies with O2 and nutrients
removes CO2 and waste products
describe how synovial fluid is replenished and absorbed
continuously replenished and absorbed by the synovial membrane, not a static pool
describe the normal viscosity and appearance of synovial fluid
high viscosity, colourless and transparent
describe how synovial fluid and viscosity are affected by joint movement
rapid joint movement associated with decreased viscosity and increased elasticity
describe the viscosity and appearance of synovial fluid in inflammation
low viscosity, straw-yellow colour and translucent
describe the viscosity and appearance of synovial fluid in septic synovial fluid
variable viscosity and colour, opaque
describe how number of WBCs and leucocytes varies between normal, inflammatory and septic synovial fluid
normal < inflammatory < septic
what are the main functions of articular cartilage
provides a low friction lubricated gliding surface, reducing wear-and-tear, and distributes the contact pressure to the subchondral bone
what type of cartilage is articular cartilage usually
hyaline
briefly describe the properties of articular cartilage
elastic and sponge-like
what is the special extracellular matrix(ECM) of articular cartilage made up of
water(70%), collagen(20%) and proteoglycans(10%)
describe the function of chondrocytes
synthesise, organise and degrade the ECM of articular cartilage
describe the ECM turnover in normal joints
the rate of degradation doesn’t exceed the rate at which it is replaced(synthesised)
describe how and what catabolic factors can affect articular cartilage ECM turnover
TNF-alpha and IL-1
stimulate proteolytic enzymes and inhibit proteoglycan synthesis
describe how and what anabolic factors can affect articular cartilage ECM turnover
TGF-beta and IGF-1
stimulate proteoglycan synthesis and counteract effects of IL-1
describe the effects on the subchondral bone if the cartilage is worn down
osteophyte formation, sclerosis in subchondral bone, cyst formation
describe the effect on the synovium in rheumatoid arthritis
synovial proliferation and inflammation
describe the effect of gout or pseudogout on a joint
deposition of crystals(e.g. uric acid)
