Physiology: Physiology of Joints Flashcards
Describe the structure of synovial joints
Bones separated by a cavity which contains synovial fluid, and united by a capsule
What effect do TNF-⍺ and IL-1 have on the extracellular matrix of articular cartilage?
Catabolic - stimulate proteolytic enzymes and inhibit proteoglycan synthesis
What is a simple synovial joint?
A synovial joint with only one pair of articular surfaces e.g. metacarpophalangeal joint
What is the function of collagen in articular cartilage?
Maintains cartilage architecture and provides tensile stiffness and strength
What effect do TGF-β and IGF-1 have on the extracellular matrix of articular cartilage?
Anabolic - stimulate proteoglycan synthesis and counteract effects of IL-1
What conditions would increase synovial fluid WBC?
Inflammatory arthritis and septic arthritis
Which type of collagen is mostly present in articular cartilage?
Type II (elastic)
What are cartilaginous joints?
Bones united by cartilage e.g. intervertebral discs
What creates the high viscosity of synovial fluid?
Hyaluronic acid (mucin) produced by the synovial cells
When would synovial fluid turn red?
In traumatic synovial tap and in haemorrhagic arthritis
Name the cells that synthesise, organise and degrade the extracellular matrix of articular cartilage
Chondrocytes
Which form of cartilage usually forms articular cartilage?
Hyaline
What is articular cartilage?
The cartilage that covers the articular surfaces of bones in a synovial joint
What is the function of water in articular cartilage?
Maintains the resiliency of the tissue and contributes to the nutrition and lubrication system
What is the function of articular cartilage?
Provides a low friction lubricated gliding surface, and distributes contact pressure to subchondral bone
What is the function of proteoglycans in articular cartilage?
Rsponsible for the compressive properties associated with load bearing (act like ‘ballons’)
What is the synovial membrane?
Vascular connective tissue that lines the inner aspect of the fibrous capsule of a synovial joint
Name the 3 components of articular cartilage
Water (70%), collagen (20%) and proteoglycans (10%)
Name the cells which produce synovial fluid
Synovial cells (fibroblasts)
What is a compound synovial joint?
A synovial joint with more than one pair of articular surfaces e.g. elbow joint
Name the three types of joints
Synovial, fibrous and cartilaginous
Describe the normal appearance of synovial fluid
Clear and colourless, with few cells
What are fibrous joints?
Bones united by fibrous tissue e.g. bones of the skull in adults
Why do the chondrocytes of articular cartilage rely on synovial fluid for O2 and removal of CO2?
Articular cartilage is avascular
