Physiology of Joints - 04/10/18 Flashcards
What are the three types of joints?
Synovial
Fibrous
Cartilaginous
What is another name for fibrous joints?
Synarthrosis
What are fibrous joints?
Bones united by fibrous tissue
Do fibrous joints allow movement?
No`
What is an example of a fibrous joint?
Skull sutures
What is another name for cartilaginous joints?
Amphiarthrosis
Do cartilaginous joints allow movement?
Yes but limited
What are some examples of cartilaginous joints?
Intervertebral discs
Pubic symphisis
Part of sacroiliac joints
Costochondral joints
What is another name for synovial joints?
Diarthrosis
What are synovial joints?
Bones separated by a cavity and united by a fibrous capsule
What is in a synovial joint?
Synovial fluid
What is the inner aspect of the fibrous capsule lined with in synovial joints?
Synovial membrane
What is the synovial membrane made of?
Vascular connective tissue
What type of cell are present in the synovial membrane?
Synovial cells aka Fibroblasts
What produces the synovial fluid?
Synovial cells
What covers the articular surfaces of bone?
Cartilage
What are the two types of synovial joints?
Simple
Compound
What is a simple synovial joint and what is an example?
One pair of articular surfaces
What is a compound synovial joint and what is an example?
More than one pair of articular surfaces
How are joints supported?
Extra-articular surfaces
What are 3 extra articular surfaces?
Bursa
Tendon
Ligament
What are the two physiological functions of joints?
Structural support
Purposeful motion
What are the 3 roles of joints during purposeful motion?
Stress distribution Confer stability -Shape of the articular component -Ligaments -Synovial fluid Joint lubrication
What provides joint lubrication?
Cartilage interstitial fluid
Synovium derived hyaluronic acid (mucin)
Synovium derived lubrcin
What are the 5 functions of synovial fluid?
Lubricates Joint Facilitates joint movements Helps minimize wear and tear Aids in nutrition of articular cartilage Supplies the chondrocytes (cartilage cells) with O2 and nutrients and removes CO2 and waste products
Is the synovial fluid a static poole?
No
It is constantly replenished and absorbed
Is synovial fluid viscous and why?
Yes
Mainly due to the presence of hyaluronic acid (mucin) produced by synovial cells
What are some other components of synovial fluid and how are they derived?
Uric acid
By dialysis of blood vessels
Are there lots of cells in the synovial fluid?
Usually very little
What does rapid movement do to the synovial fluid?
Decreases viscosity
Increases elasticity
What is an example of a condition where the synovial fluid becomes defective?
Osteoarthritis
What does normal synovial fluid look like/
Clear and colourless
How many WBCs are in synovial fluid?
<200WBC/mm3
When does the WBC count increase in the synovial fluid?
Inflammatory and septic arthritis
When does the synovial fluid turn red?
Traumatic synovial tap
Haemorrhagic arthritis
What colour is inflammatory synovial fluid?
Yellow
What are the two functions of articular cartilage?
Prevents wear and tear
Distributes contact pressure to subchondral bone
What determines the mechanical properties of cartilage?
The composition of the cartilage ECM and the interaction between the fluid and solid phase of cartilage
From superior to inferior, name the structure of articular cartilage?
Articular surface Superficial zone Middle zone Deep zone Calcified zone Subchondral bone
How are the zones of articular cartilage differ?
Organization of collagen fibres and relative content of cartilage components
What type of cartilage is articular cartilage?
Hyaline
What are the properties of articular cartilage?
Elastic
Sponge-like
Where does articular cartilage cover?
Articular surfaces of bones
What is the ECM made up of?
70% Water
20% Type 2 collagen
10% Proteoglycans
What accounts for 70% of the cartilage wet weight?
Water
Where is 80% of cartilage water distributed?
Near the articular surface
What happens to cartilage water content with age?
It decreases
What does the water in cartilage allow?
Maintains resiliency of the tissue and contributes to the nutrition and lubrication system
What accounts for 20% of the cartilage wet weight?
Collagen
What type of collagen is present in cartilage?
Type 2
What in the function of the collagen in the cartilage?
Maintains cartilage architecture
Provides tensile stiffness and strength
What accounts for 10% of cartilage wet weight?
Proteoglycan
Where is the highest concentration of proteoglycan found?
Middle and deep zone
What is proteoglycan composed of?
Mainly glycosaminoglycan
What is proteoglycan responsible for?
Compressive properties associated with load bearing
What makes up >98% of cartilage volume?
ECM
What synthesizes, organizes, degrades and maintains the ECM?
Chondrocytes
Is the articular cartilage vascular or avascular?
Avascular
What happens when there are changes in the amounts of each cartilage component?
It would change the mechanical properties of cartilage
What would happen if the rate of ECM degradation happened faster than the rate of its synthesis?
Joint disease
What are the catabolic factors of cartilage matrix turnover?
Stimulate proteolytic enzymes and inhibits proteoglycan synthesis
E.g. TNFa, IL-1
What are the anabolic factors of the cartilage matrix turnover?
Stimulates proteoglycan syntheis and counteracts the effects of IL-1
E.g. TGF, IGF-1
What are 2 markers of cartilage degradation?
Serum and synovial keratin sulphate
-increased levels indicate cartilage breakdown
-Level increases with age and patients with osteoarthritis
Type II collagen in synovial fluid
-Increased levels indicate cartilage breakdown
-Useful in evaluating cartilage erosion
What can cause Rheumatoid arthritis?
Synovial cell proliferation
Inflammation
What causes gouty arthritis?
Deposition of uric acid crystals
What causes soft tissue rheumatism?
Injury and inflammation to periarticular structures
What are 6 effects on the subchondral bone following cartilage wear and tear?
Thickened capsule Cyst formation Sclerosis in subchondral bone Fibrillated cartilage Synovial hypertrophy Osteophyte formation
