Physiology: Joints Flashcards
fibrous joints
- syndesmoses and sutures
- dont allow any movement
syndesmoses example
interosseous membrane between tibia and fibia
example of 1y and 2y cartilaginous joint
- 1y - hyaline cartilage on the end of bones
- 2y - intervertebral discs
- allow limited movement
name 4 cartilaginous joints
- pubic symphysis
- intervertebral disc
- part of SI joints
- costochondral joints
amphiarthorisis
cartilaginous joint
diarthrosis
synovial joint
what is the synovial membrane made up of
vascular connective tissue with capillary networks and lymphatics
what does the synovial membrane do
contains synovial cells (fibroblast) which produce synovial fluid
define simple synovial joint
one articular surface eg metacarpophalangeal joint
define compound synovial joint
>1 articular surfaces eg elbow joint
how are joints additionally supported
extra articular structures
how does a joint confer stability during purposeful motion
shape of articular component, ligament and synovial fluid that acts as an adhesive seal
how is joint lubrication provided
- cartilage interstitial fluid
- synovial fluid is made up of hyaluronic acid and lubrcin
what does the synovial fluid supply the chondrocytes with
O2 and nutrients and removes Co2 and waste products
where is the synovial fluid found
fills the joint cavity
is the synovial fluid static pool or is it replenished
replenished and absorbed by synovial membrane
what is the viscosity of the synovial fluid like
- high
- mainly due to hyaluronic acid (mucin) that is produced by synovial cells and is in the synovial fluid
- varies with joint movement
what cells does the synovial fluid normally contain
few mononuclear leucocytes
describe the relationship between synovial fluid viscosity and elasticity and joint movement
rapid movement is associated with decrease viscosity and increased elasticity
describe the relationship between synovial fluid viscosity and elasticity and joint movement on a person with a diseased joint
properties become defective - joint is more viscose and less elastic on movement
what does normal synovial fluid look like
clear and colourless
when would synovial fluid turn red
traumatic synovial tap and haemorrhagic arthritis
what is the viscosity of inflammatory synovial fluid like
low
what does a high polymorph count do to the colour of synovial fluid
makes it cloudy
what are the functions of articular cartilage
prevents wear and tear, distributes contact pressure to subchondral bone
describe the structure of articular cartilage
- several zones that differ in organisation of collagen fibres and relative content of cartilage components
- water is highest near the articualr surface
what is the composition of the ECM of articular (hyaline cartilage)
- 75% water
- 25% type II collagen fibres and proteoglycans (made from GAGs)
what are the functions of the water in cartilage
maintain resiliency of tissue and contribute to nutrition and lubrication
what happens to the water nd collagen content of cartilage with age
decrease
how is water distributed in cartilage
unevenly - mainly near articular surface
what is the function of collagen in cartilage
type II maintain cartilage architecture and provide tensile stiffness and strength
is there more collagen or proteoglycan in cartilage
collagen - 20% proteoglycan - 10%
what is proteoglycan composed of
- mainly GAGs
- eg chondroitin sulphate
- composition changes with age eg chondroiton decreases
what is the function of proteoglycan
compressive properties that are associated with load bearing
what is the ECM in cartilage made and maintained by
chondrocytes
how does articular cartilage receive 02 and nutrients
avascular - via synovial fluid
what substances degrade ECM
metalloproteinase proteolytic enzymes eg collagenase and stromelysin
describe the rate of degradation and synthesis of ECM
usually balanced, joint disease occurs if degradation>synthesis
name 2 catabolic factors for ECM turnover
TNF alpha and IL 1 (cytokines)
name 2 anabolic factors for ECM turnover
TGF - beta and IGF 1
name 2 markers of cartilage degradation
- serum and synovial keratin sulphate
- type II collagen in synovial fluid
what do increased levels of keratin sulphate in serum and synovial fluid indicate
cartilage breakdown - increase in patients with OA
what is type II collagen in synovial fluid marker useful for
evaluating cartilage erosion eg osteoarthritis and rheumatoid arthritis
osteoarthritis
can be caused by cartilage and synovial composition and function deteriorate with age and repeated wear and tear
what does deposition of salt (uric acid) crystals in joint cause
gouty arthritis
what does synovial cell proliferation and inflammation cause
rheumatoid arthritis
what does deposition of rhomboid shaped Ca pyrophosphate crystals cause
pseudo gout
