9: Physiology of joints Flashcards
What are the three types of joint found in the body?
Synovial
Fibrous
Cartilaginous
In synovial joints, bones are separated by a ___ and joined by a fibrous ___.
cavity
capsule
What does a synovial cavity contain?
Synovial fluid
What is the inner part of the capsule lined by?
Synovial membrane
The synovial membrane is vascularised by ___.
capillaries
Which cells, found in the synovial membrane, produce synovial fluid?
Fibroblasts
Which parts of bone in a synovial joint are covered in hyaline cartilage?
Articular parts
simple
compound
Joints provide structural ___ to the skeleton and allow for purposeful ___.
support
movement
joint lubrication
What is the main function of synovial fluid?
Lubricates joint to reduce friction between articular surfaces
Articular cartilage (hyaline) has no vascular supply.
How is it kept alive?
Nourished by synovial fluid
i.e supplies O2 and removes CO2/waste
Synovial fluid totally fills the joint cavity - how much synovial fluid is found in the adult knee?
3.5ml
Synovial fluid is constantly ___ and ___ by the synovial membrane.
absorbed , replenished
Which chemical, found in synovial fluid, makes it highly viscous?
Hyaluonic acid (mucin)
Does the synovial fluid contain any cells?
Yes, some white blood cells
and chondrocytes
viscosity vs elasticity
What colour is synovial fluid?
Clear and colourless
When does the WBC of synovial fluid increase?
Inflammatory / septic arhritis
Why may synovial fluid turn red?
Iatrogenic - traumatic aspiration
Haemorrhagic arthritis
What colour does inflammatory synovial fluid turn?
Yellow
Generally, the more inflamed a synovial joint is, the more (transparent / opaque) the fluid will become.
opaque i.e can’t see through it
What is the main function of articular cartilage?
Reduces friction and pressure to prevent wear-and-tear of joints
The vast majority of cartilage is ___ ___.
extracellular matrix
What are the two “sides” of cartilage in relation to the joint cavity?
Subchondral zone - close to the bone
Articular surface - touching cavity / other bone
structure of articular cartilage
What is articular cartilage usually made of?
Hyaline
Articular cartilage is (rigid / elastic) and (solid / spongy).
elastic , spongy
What is the main constituent of cartilage?
Water
Which fibre makes up 20% of cartilage and allows it to be elastic?
Type II collagen
What makes up the other 10% of cartilage?
Proteoglycans
Water, collagen and proteoglycans found in cartilage all (increase / decrease) with age.
decrease
properties of water, collagen and proteoglycans
What makes up 98% of the total volume of cartilage?
Extracellular matrix
Which cells maintain the extracellular matrix of cartilage?
Chondrocytes
Articular cartilage is avascular.
How do chondrocytes receive oxygen?
Synovial fluid
Normally, the rates of synthesis and degradation of ECM are ___.
equal
Changes in the proportions of water, collagen and proteoglycans affect the ___ of cartilage.
properties
Apart from changes in the proportions of its constituent parts, what is another cartilage-related cause of joint diseae?
Rate of ECM degradation > Rate of ECM synthesis
catabolic & anabolic factors
markers of degradation
What joint condition is caused by wear and tear of cartilage and the synovial cavity?
Osteoarthritis
Which joint condition is caused by synovial cell proliferation and inflammation?
Rheumatoid arthritis
Deposition of crystals e.g uric acid in joints causes ___.
gout
soft tissue rheumatism
