Joints, Synovial Fluid and Cartilage

Question 1

What are the 3 types of joints?

Answer 1

Fibrous

Cartilaginous

Synovial

Question 2

What are examples of fibrous joints?

Answer 2

• Cranial sutures
• Periodontal ligament
• Interosseous membranes

Question 3

What are the different categories of cartilaginous joints?

Answer 3

• Primary cartilaginous joint (synchondrosis)
  
  • Only hyaline cartilage
• Secondary cartilaginous joint (symphysis)
  
  • Hyaline and fibrocartilage

Question 4

What are some of the features of a synovial joint?

Answer 4

Question 5

What are the different kinds of synovial joints?

Answer 5

Plane

Hinge

Pivot

Condylar

Saddle

Ball and socket

Question 6

What is hyaline cartilage also known as?

Answer 6

Articular cartilage

Question 7

What are the different layers of articular cartilage in a synovial joint?

Answer 7

• Superficial/tangential layer
  
  • Flattened chondrocytes that produce collagen and glycoproteins (such as lubcricin)
• Transitional layer
  
  • Round chrondrocytes that produce proteoglycans such as aggrecan

Question 8

What percentage of articular cartilage is water?

Answer 8

>75%

Question 9

What are some categories of molecules formed from carbohydrates and water?

Answer 9

• Glycoproteins
  
  • Such as lubricin
  • Proteins to which oligosaccharide chains are attached (so more protein than carb)
• Proteoglycans
  
  • Such as aggrecan
  • Proteins that are heavily glycosylated (protein core to which one or more GAGs attach)(tend to be more carbs than protein)
• Glycosaminoglycans or GAGs
  
  • Such as hyaluronic acid
  • Long unbranched polysaccharides which are highly polar and thus attract water

Question 10

What kind of molecule is hyaluronic acid?

Answer 10

Glycosaminoglycan

Question 11

What are Glycosaminoglycans (GAGs)?

Answer 11

• Long unbranched polysaccharides which are highly polar and thus attract water

Question 12

What is the average thickenss of articular cartiage in synovial joints?

Answer 12

• Average 2-3mm
• Interphalangeal joint 1mm
• Patella 5-6mm

Question 13

Decribe the vascularity, nerves and lymphatics of cartilage?

Answer 13

• Avascular
• Aneural
• Alymphatic

Question 14

What is synovial fluid produced by?

Answer 14

Synovial fluid is produced by synovial membrane (synovium)

Question 15

How does direct exchange of oxygen, CO2 and metabolites take place with cartilage?

Answer 15

Direct exchange of oxygen, carbon dioxide and metabolites is done between blood and synovial fluid

Question 16

What cells in the synovium (synovial membrane) produces the fluid?

Answer 16

• Synoviocytes producing the fluid
  
  • Different types, A
    
    • Look like macrophages, remove debris
    • Contribute to synovial fluid production
  • B
    
    • Fibroblast like
    • Main producer of synovial fluid

Question 17

What type of synoviocyte is the main producer of synovial fluid?

Answer 17

Type B

Question 18

Describe the capillary network and epithelial lining of the synovium?

Answer 18

• Rich capillary network
• No epithelial lining

Question 19

What is synovial fluid formed from?

Answer 19

• Formed from hyaluronic acid and lubricin with a fluid component from blood plasma

Question 20

What is the turnover of synovial fluid?

Answer 20

• Rapid turnover (about 2 hours)

Question 21

What are some of the functions of synovial fluid?

Answer 21

• Nutrition of cartilage (articular c., menisci/discs)
• Removal of waste products
• Lubrication -> less friction -> less wear

Question 22

What are bursae?

Answer 22

• Is a small fluid filled sacs lined by synovial membrane with an inner capillary layer of viscous synovial fluid

Question 23

What is the function of bursae?

Answer 23

• Function is to reduce friction

Question 24

What happens to the viscosity of synovial fluid and the water content of cartlage as you age?

Answer 24

• Viscosity of synovial fluid increases
  
  • Slower joint movements
  • Reduced lubrication
• Water content of cartilage decreases
  
  • Reduced shock absorption