joint physiology Flashcards
where do you find fibrous joints and what is there function
units bone and allows no movement eg skull
where do you find cartilaginous joints and what is there function
joins bones and allows limited movements eg vertebral disc and pubic symphysis
what is a synovial joint
articular (fibrous) capsule surrounding joint filled with synovial fluid
what is the inner part of the synovial capsule made of what covers articulating bones
synovial membrane - supplied with capillaries and lymphatics, contain synovial fibroblasts which produce fluid
what covers articulating bones in synovial joint
hyaline cartilage
what is the difference between compound and simple joints
compound have more than 1 articular surface eg elbows, simple joints have one articular surface eg fingers
what are the purposeful motion function of joints
stress distribution and shock absorption
how are synovial joints adapted for stability
shape of articular component, ligaments, synovial fluid
how are synovial joints lubricated
interstitial fluid, hyaluronic acid (mucin) and lubricin produced by synovium
what are the functions of synovial fluid
lubricates joint, allows movement, limits friction and wear and tear, provides nutrition for articular cartilage, supplies chondrocytes with O2 and removes CO2
what replenishes and absorbs synovial fluid
synovial membrane
synovial fluid is usually clear and colourless with few cells, what could change this
inflamm and septic arthritis = increased WBC. trauma and haemorrhagic arthritis = turns red
during movement, what happens to the viscosity and elasticity of synovial fluid
less viscosity and increased elasticity
what is the function of articular cartilage
low friction lubrication, distributes pressure on bones
what type of cartilage is articular cartilage made of
hyaline - spongy/ elastic
what is the majority of cartilage
ECM 98%, synthesised and degraded by chondrocytes (2%)
how is articular cartilage nourished
synovial fluid
what is the composition of the ECM in cartilage
70% water, 20% type II collagen, 10% proteoglycans
what is the function of water in ECM
unevenly distributes (more at articular surfaces), decreased with age, helps with resilience, nutrition and lubrication
what is the function of type II collagen in ECM
structure, strength and stiffness
what is the function of proteoglycans in ECM
mostly in middle/ deep zones, compressive properties for load bearing
what happens when the rate of ECM degradation> replenishment
disease
what are catabolic factors of ECM turnover
stimulate proteolytic enzymes and inhibit proteoglycans eg TNF and IL1
what are anabolic factors of ECM turnover
stimulates proteoglycans and counter effects IL1 eg tumour and insulin growth factors
what are ECM markers of degradation
serum/ synovial keratin sulphate (increases with age and osteoarthritis)
what happens to cartilage with reduced ECM turnover
cartilage breakdown and erosion
