Physiology of Joints Flashcards
What are the 3 main types of joints in the body and give an example of each
Synovial (knee)
Fibrous (skull)
Cartilaginous (intervertebral discs)
What are the 3 main types of joints in the body and give an example of each
Synovial (knee)
Fibrous (skull)
Cartilaginous (intervertebral discs)
How are fibrous joints joined?
Describe the range of movement in this joint
United by fibrous tissue
They do not allow any movement
How are carilaginous joints joined?
United by cartilage
Allow limited movement
How are the bones of a synovial joint separeated
By a cavity containing synovial fluid and united by a fibrus capsule
What part of a synovial joint is lined with synovial membrane
The inner aspect of fibrous capsule
What is the synovial membrane made up of?
Vascular connective tissue with capillary entworks and lymphatics
What does the synovial membrane contain
Synovial cells (fibroblasts) which produce the synovial fluid
What are the articular surfaces of bones covered with
Cartilage
What can synovial joints be classified into and give examples of these
Simple (metacarpophalangeal joint) - One pair of articular surfaces
Compound (elbow joint) - more than one pair of articular surfaces
What are 3 main extra-articular structures to support synovial joints
Ligaments, tendons and bursa
What are the physiological fucntions of joints
To serve the functional requirements of the MSK system
Structural support and purposeful motion
WHat are the 3 main roles of joints during purposeful motion
Stress distribution
Confer stability
Joint lubrication
How does the synovial fluid confer stability
It acts as an adhesive seal that freely permits sliding motion between cartilaginous surfaces
How do ligaments confer stability
Provide a second major stabilising influence
WHat are the 5 functions of synovial fluid
Lubrication of the joint
Facilitates joint movements
Helps minimise wear and tear of joints through lubrication
Aids in the nutrition of articular cartilage
Supplies the chondrocytes (cartilage cells) with O2 and nutrients and remove O2 and waste producets
WHere is the synovial fluid located?
It fills the joint cavity (
How does the synovial fluid not become a static pool
It is continuously replenished and absorbed by the synovial membrane
Describe the viscosity of the synovial fluid
It has a high viscosity - due to the presence of hyaluronic acid (mucin)
How does te viscosity of the synovial fluid vary
With joint movement
What also changes during joint movement
The elasticity of synovial fluid
What is rapid movement associated with
Decreased viscosity and increased elasticity
What happens to the viscosity and elasticity of a joint in a diseased joint (osteoarthritis)
The viscosity and elasticity become defective
Describe the appearance of normal synovial fluid
Clear and colourless
How many WBC are present
What happens to the WBC count in inflammatory and septic arthritis
THe count increases
What happens to the appearance of synovial fluid in traumatic synovial tap and in haemorrhagic arthritis
It turns red
what causes the synovial fluid to appear thin and opaque
The very high polymorph count
What is the main functions of articular cartilage
It provides a low fruction lubricated gliding surface to help revent wear and tear of joints
It distributes contact pressure to subchodral bone
What plays a significant role in determining the mechanical properties of cartilage
The composition of the cartilage ECM and the interaction between the fluid and sold phase
What causes the zones to differ in the structure of articular cartilage
Organisation of collagen fibres and relative content of cartilage components
What are the 4 zones of articular cartilage
Superficial
Middle
Deep
Calcified
The articular cartilage is usually what?
Hyaline
Describe the properties of articular cartilage
Elastic and sponge like
Covers the articuar surfaces of bones
What is articular cartilage made up of
Predominantly water (70%) and collaged (20%) and Proteoglycans (10%)
Where is the highest proportion of water in the cartilage
Near the articular surface
What happens to the cartilage water content with age
It decreases with age
What is the function of water in cartilage?
To maintain the resiliency of the tissue and contribute to the nutrition and lubrication system
What does collagen provide in cartilage
Tensile stiffness and strength
Where is the highest concentration of proteoglycan found in the cartilage
In the middle and deep zone
WHat is proteoglycan composed of
Mainly glycosaminoglycan e.g. chondriotin sulphate
What happens to the composition of cartilage proteoglycan with age
It changes - chondriotin decreases with age
What is proteoglycan responsible for
The compressive properties associated with load bearing
What synthesises, organises , degrades and maintains the ECM
Chondroxytes (cartilage cells)
Describe the relationship between the rate of ECM degradation and the rate at which it is replaced
The rate of ECM degradation doesnt exceed the rate at which it is replaced
What would occur if the rate of ECM degradation were to exceed the rate of its synthesis
Joint disease would occur
What would occur if the rate of ECM degradation were to exceed the rate of its synthesis
Joint disease would occur
How are fibrous joints joined?
Describe the range of movement in this joint
United by fibrous tissue
They do not allow any movement
How are carilaginous joints joined?
United by cartilage
Allow limited movement
How are the bones of a synovial joint separeated
By a cavity containing synovial fluid and united by a fibrus capsule
What part of a synovial joint is lined with synovial membrane
The inner aspect of fibrous capsule
What is the synovial membrane made up of?
Vascular connective tissue with capillary entworks and lymphatics
What does the synovial membrane contain
Synovial cells (fibroblasts) which produce the synovial fluid
What are the articular surfaces of bones covered with
Cartilage
What can synovial joints be classified into and give examples of these
Simple (metacarpophalangeal joint) - One pair of articular surfaces
Compound (elbow joint) - more than one pair of articular surfaces
What are 3 main extra-articular structures to support synovial joints
Ligaments, tendons and bursa
What are the physiological fucntions of joints
To serve the functional requirements of the MSK system
Structural support and purposeful motion
WHat are the 3 main roles of joints during purposeful motion
Stress distribution
Confer stability
Joint lubrication
How does the synovial fluid confer stability
It acts as an adhesive seal that freely permits sliding motion between cartilaginous surfaces
How do ligaments confer stability
Provide a second major stabilising influence
WHat are the 5 functions of synovial fluid
Lubrication of the joint
Facilitates joint movements
Helps minimise wear and tear of joints through lubrication
Aids in the nutrition of articular cartilage
Supplies the chondrocytes (cartilage cells) with O2 and nutrients and remove O2 and waste producets
WHere is the synovial fluid located?
It fills the joint cavity (
How does the synovial fluid not become a static pool
It is continuously replenished and absorbed by the synovial membrane
Describe the viscosity of the synovial fluid
It has a high viscosity - due to the presence of hyaluronic acid (mucin)
How does te viscosity of the synovial fluid vary
With joint movement
What also changes during joint movement
The elasticity of synovial fluid
What is rapid movement associated with
Decreased viscosity and increased elasticity
What happens to the viscosity and elasticity of a joint in a diseased joint (osteoarthritis)
The viscosity and elasticity become defective
Describe the appearance of normal synovial fluid
Clear and colourless
How many WBC are present
Less than 200WBC/mm3
What happens to the WBC count in inflammatory and septic arthritis
THe count increases
What happens to the appearance of synovial fluid in traumatic synovial tap and in haemorrhagic arthritis
It turns red
what causes the synovial fluid to appear thin and opaque
The very high polymorph count
What is the main functions of articular cartilage
It provides a low fruction lubricated gliding surface to help revent wear and tear of joints
It distributes contact pressure to subchodral bone
What plays a significant role in determining the mechanical properties of cartilage
The composition of the cartilage ECM and the interaction between the fluid and sold phase
What causes the zones to differ in the structure of articular cartilage
Organisation of collagen fibres and relative content of cartilage components
What are the 4 zones of articular cartilage
Superficial
Middle
Deep
Calcified
The articular cartilage is usually what?
Hyaline
Describe the properties of articular cartilage
Elastic and sponge like
Covers the articuar surfaces of bones
What is articular cartilage made up of
Predominantly water (70%) and collaged (20%) and Proteoglycans (10%)
Where is the highest proportion of water in the cartilage
Near the articular surface
What happens to the cartilage water content with age
It decreases with age
What is the function of water in cartilage?
To maintain the resiliency of the tissue and contribute to the nutrition and lubrication system
What does collagen provide in cartilage
Tensile stiffness and strength
Where is the highest concentration of proteoglycan found in the cartilage
In the middle and deep zone
WHat is proteoglycan composed of
Mainly glycosaminoglycan e.g. chondriotin sulphate
What happens to the composition of cartilage proteoglycan with age
It changes - chondriotin decreases with age
What is proteoglycan responsible for
The compressive properties associated with load bearing
What synthesises, organises , degrades and maintains the ECM
Chondroxytes (cartilage cells)
Describe the relationship between the rate of ECM degradation and the rate at which it is replaced
The rate of ECM degradation doesnt exceed the rate at which it is replaced
What would change the mechanical properties of cartilage?
Changes in the relative amounts of the three major components of cartilage (water, collagen and proteoglycans)
What would occur if the rate of ECM degradation were to exceed the rate of its synthesis
Joint disease would occur
What are the catabolic factors of cartilage matrix turnover
Stimulate proteolytic enzymes and inhibit proteoglycan synthesis
What are the anabolic factors of cartilage matrix turnover
Stimulate proteoglycan synthesis and counteract effects of IL-1
What are the 2 main markers of cartilage degredation
Serum and synovial keratin sulphate
Type 2 collagen in synovial fluid
What indicates cartilage breakdown
Increased levels of both serum and synovial keratin sulphate OR increased evels of type 2 collagen in synovial fluid
What happens to the serum and synovial keratin sulphate levels with age?
They increase
Why is measuring the type 2 collagen in synovial fluid useful?
In evaluating cartilage erosion (e.g. in osteoarthritis and rheumatoid arthritis)
What gives rise to osteoarthritis
Cartilage and synovial composition and function deteriorate with age and repeated wear and tear
What causes rheumatoid arthritis
Synovial cell proliferation and inflammation
What causes gouty arthritis
Deposition of salt crystals (uric acid)
What causes soft tissue rheumatism (e.g. injury tot he tendon causes tendonitis)
Injury and inflammation to periarticular structures
Give 6 examples of changes that can occur in an osteoarthritic knee
Cyst formation Sclerosis in subchondral bone Osteophyte formation fibrillated cartilage synovial hypertrophy thickened capsule
What histologically causes gouty arthritis
Deposition of needle shaped uric acid crystals
What causes pseud-gout
Deposition of rhomboid shaped calcium pyrophosphate crystals
