Structure & function of cartilage and joints

Question 1

Name the different types of connective tissue and their functions

Answer 1

Fibroblast: secretes ECM for most tissues - collagen and elastin

Chondrocyte: secretes ECM for cartilage - collagen II

Osteoblast: secretes ECM of bone collagen I

Myofibroblast: secrete ECM and have contractile function

Adipocyte: storage and metabolism of fat

Question 2

What is the importance of cartilage

Answer 2

Support function
Shock absorbers for soft tissue & sliding area of joints
Provides template for growth and bone length
Have limited capacity for regeneration in reposes to traumatic injury

Question 3

Name the different types of cartilage & its functions

Answer 3

Hyaline cartilage: Type II collagen. Smooth glassy surface

Elastic cartilage: Type II collagen + elastin

Fibrocartilage: Type II & I collagen. Strong.

Question 4

Name the types of joints and their functions

Answer 4

Non synovial - limited movement. No surface and dense connective tissue. Fibrous e.g skull. Hyaline cartilage at 1st rib and sternum.

Synovial - extensive movement. Free articular surfaces. Bone ends covered with hyaline cartilage. Low friction & shock absorbing.
Synovial fluid to lubricate joint

Question 5

Name a non-synovial joint disease

Answer 5

IV disc degeneration
- Due to wear & tear
- Weakening of the annulus fibrosus bulge and nucleus pulpous extrude
- Often leads to IV disc sciatica

Question 6

Describe the function of hyaline cartilage at joints

Answer 6

Resist compression due to elasticity of stiffness of proteoglycans
Tensile strength
Limited repair

Question 7

What is Osteoarthritis, explain the different pathologies and its risk factors

Answer 7

• Wear and tear disease
• Loss of articular cartilage and synovitis due to inflammation
• No known cause

RISK FACTORS:
- Age (older)
- Gender (more women)
- Obesity (extra strain on joints)
- Genetics

PATHOLGIES:
- Altered composition of cartilage: reduced proteoglycans and collagen
- Surface cracks & burnished from ear (eburnation)
- Osteophytes allowing bony outgrowth
- Fracture gaps making synovial fluid enter subchondral regions forming cysts

Question 8

What is Rheumatoid Arthritis and name some pathological factors

Answer 8

• Autoimmune disease
• Due to genetic and environmental factors
• Swelling & stiffness often in wrists and phalangeal joints

PATHOLGIES:
- Genetic deposition cause production of cytokines, TNF, IL-1 which causes destruction of articular cartilage and underlying bone
- Genetic deposition can also release inflammatory cells and enzymes which destroy cartilage
- Synovial priliferation also destroys cartilage