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 type of cartilage is present in synchondrosis cartilage joints?

Answer 4

Only hyaline cartilage

Question 5

What type of cartilage is present in symphysis cartiliginous joints?

Answer 5

Hyaline and fibrocartilage

Question 6

What are primary cartilagnious joints also known as?

Answer 6

Synchondrosis cartilaginous joints

Question 7

What are secondary cartilaginous joints also known as?

Answer 7

Symphysis cartilaginous joints

Question 8

What are some of the features of a synovial joint?

Answer 8

Question 9

What are the different kinds of synovial joints?

Answer 9

Plane

Hinge

Pivot

Condylar

Saddle

Ball and socket

Question 10

Joint stability is achieved by what?

Answer 10

• Shape of articulating surfaces
• Capsule and ligaments
• Muscles

Question 11

What is hyaline cartilage also known as?

Answer 11

Articular cartilage

Question 12

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

Answer 12

Superficial/tangential layer

• flattened chondrocytes produce collagen & glycoproteins (eg lubcricin)

​Transitional layer

• round chondrocytes produce proteoglycans (eg aggrecan)

Question 13

What is produced in the superficial layer of articular cartilage in a synovial joint?

Answer 13

• Flattened chondrocytes that produce collagen and glycoproteins (such as lubcricin)

Question 14

What is produced in the transitional layer of articular cartilage in a synovial joint?

Answer 14

Round chrondrocytes that produce proteoglycans such as aggrecan

Question 15

How does the orientation of collagen in articular cartilage in a synovial joint change from superficial to deep?

Answer 15

• Change in collagen orientation from superficial to deep layers

Question 16

What percentage of articular cartilage is water?

Answer 16

>75%

Question 17

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

Answer 17

• glycoproteins (eg lubricin): proteins to which oligosaccharide chains are attached (more a protein than carb)
• proteoglycans (eg aggrecan): proteins that are heavily glycosylated (protein core to which one or more GAGs attach)(more a carb than protein)
• glycosaminoglycans or GAGs (eg hyaluronic acid): long unbranched polysaccharides which are highly polar and thus attract water

Question 18

What kind of molecule is lubrican?

Answer 18

Glycoprotein

Question 19

What is a glycoprotein?

Answer 19

• Proteins to which oligosaccharide chains are attached (so more protein than carb)

Question 20

What kind of molecule is aggrecan?

Answer 20

Proteoglycan

Question 21

What is a proteoglycan?

Answer 21

• Proteins that are heavily glycosylated (protein core to which one or more GAGs attach)(tend to be more carbs than protein)

Question 22

Do proteoglycans tend to have more carbohydrates or proteins?

Answer 22

Carbohydrates

Question 23

What does GAGs stand for?

Answer 23

Glycosaminoglycans

Question 24

What kind of molecule is hyaluronic acid?

Answer 24

Glycosaminoglycan

Question 25

What are Glycosaminoglycans (GAGs)?

Answer 25

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

Question 26

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

Answer 26

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

Question 27

Decribe the vascularity, nerves and lymphatics of cartilage?

Answer 27

* Avascular * Aneural * Alymphatic

Question 28

What is synovial fluid produced by?

Answer 28

Synovial fluid is produced by synovial membrane (synovium)

Question 29

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

Answer 29

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

Question 30

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

Answer 30

synoviocytes type A - look like macrophages, remove debris - contribute to synovial fluid production type B - fibroblast like - main producer of synovial fluid

Question 31

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

Answer 31

Type B

Question 32

Describe the capillary network and epithelial lining of the synovium?

Answer 32

* Rich capillary network * No epithelial lining

Question 33

What is synovial fluid formed from?

Answer 33

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

Question 34

What is the turnover of synovial fluid?

Answer 34

* Rapid turnover (about 2 hours)

Question 35

What are some of the functions of synovial fluid?

Answer 35

- nutrition of cartilage - removal of waste products - lubrication -\> less friction -\> less wear

Question 36

How does synovial fluid achieve its lubricating function?

Answer 36

boundary: glycoproteins (lubricin) bind to receptors on articular surfaces to form a thin film hydrodynamic: surfaces kept apart by liquid pressure (viscosity changes with load and velocity of movement) weeping: fluid in cartilage is squeezed out into synovial cavity to increase fluid volume

Question 37

What are bursae?

Answer 37

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

Question 38

What is the function of bursae?

Answer 38

* Function is to reduce friction

Question 39

What is inflammation of bursae called?

Answer 39

Bursitis

Question 40

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

Answer 40

- viscosity of synovial fluid increases - water content of cartilage decreases

Question 41

What are consequences of the viscocity of synovial fluid increasing?

Answer 41

* Slower joint movements * Reduced lubrication

Question 42

What is a consequence of decreased water content of cartilage?

Answer 42

* Reduced shock absorption

Question 43

What disease can be a consequence of ageing and its affects on synovial fluid and cartilage?

Answer 43

Osteoarthritis