Joints and Synovial Fluid and Cartilage

Question 1

Name the 3 types of joints

Answer 1

Fibrous, cartilaginous, synovial

Question 2

What is the structure of a fibrous joint?

Answer 2

Bone - connective tissue (collagen fibres) - bone

Question 3

What is the structure of a cartilaginous joint?

Answer 3

Bone - cartilage - bone

Question 4

Where are fibrous joints found in the body?

Answer 4

Cranial sutures, periodontal ligament, interossus membranes (radius and ulna)

Question 5

What are the two types of cartilaginous joints?

Answer 5

Primary - only hyaline Secondary - hyaline and fibrocartilage

Question 6

Describe primary cartilaginous joints

Answer 6

Also known as synchondrosis

Question 7

Describe secondary cartilaginous joints

Answer 7

Also known as symphysis

Question 8

Describe a synovial joint

Answer 8

Question 9

What may a synovial joint also contain?

Answer 9

Articular discs, ligaments, bursae

Question 10

Name the 6 types of synovial joint

Answer 10

Question 11

Name 4 factors that encourage joint stability

Answer 11

Shape of articulating surfaces, capsule, ligaments, muscles

Question 12

Articular cartilage is what type of cartilage?

Answer 12

Hyaline

Question 13

What is the syperficial/tangential layer of articular cartilage made from?

Answer 13

Flattened chondrocytes that produce collagen and glycoproteins (e.g. lubricin)

Question 14

What is the transitional layer of articular cartilage made from?

Answer 14

Round chondrocytes that produce proteoglycans such as aggrecan

Question 15

Describe the change in orientation of collagen fibres throught the layers of articular cartilage

Answer 15

Question 16

What is the articular cartilage water content?

Answer 16

>75% - water is incompressible so protects the tissue from compression

Question 17

What are glycoproteins?

Answer 17

Proteins to which oligosaccharide chains are attached, i.e.more a protein than a carbohydrate (e.g. lubricin)

Question 18

What are proteoglycans?

Answer 18

Proteins that are heavily glycosylated (= a protein core to which one or more GAGs attach), i.e. tend to be more carb than protein (e.g. aggrecan)

Question 19

What are glycosaminoglycans (GAGs)?

Answer 19

Long unbranched polysaccharides, which are highly polar and thus attract water (e.g. hyaluronic acid) - good at attracting water as they are polar

Question 20

Describe articular cartilage thickness

Answer 20

Avergae - 2-3mm

Interphalageal - 1mm (not load-bearing)

Patella - 5-6mm

Question 21

Catilage is avascular, aneural and alymphatic so how are nutrients transporteed to cartilage and waste products removed?

Answer 21

Synovial fluid produced by the synovial membrane (synvoium - type of tissue that makes up the membrane)

Question 22

What does the synovium contain?

Answer 22

Synoviocytes - produce synovial fluid

Rich capillary network

No epithelial lining - direct exchange of O2, CO2 and metabolites between blood and synovial fluid

Question 23

What are the 2 types of synoviocytes?

Answer 23

Type A and type B

Question 24

Describe type A synoviocytes

Answer 24

Look like macrophages

Remove debris

Contribute to synovial fluid productin - not main producers

Question 25

Describe type B synoviocytes

Answer 25

Fibroblast-like Main producer of synovial fluid

Question 26

Describe synovial fluid

Answer 26

Viscous fluid Hyaluronic acid & lubricin Fluid component (from blood plasma)

Question 27

Describe the volume and turnover time of synovial fluid

Answer 27

Small volumes (knee joint: ̴0.5 ml ) Rapid turnover ( ̴2 hours)

Question 28

Name 3 functions of synovial fluid

Answer 28

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

Question 29

Name the 3 forms of lubrication

Answer 29

Boundary, hydrodynamic (aquaplaning), weeping

Question 30

Describe boundary lubrication

Answer 30

Glycoproteins such as lubricin bind to receptors on articular surfaces to form a thin film

Question 31

Describe hydrodynamic lubrication

Answer 31

Surfaces kept apart by liquid pressure Viscosity changes with load and velocity of movement

Question 32

Describe weeping lubrication

Answer 32

Fluid that is present in the cartilage is squeezed out into the synovial cavity to increase fluid volume

Question 33

What is a bursa?

Answer 33

Fluid-filled sac made up of synovial membrane. Tend to sit in areas where there is high risk of friction. Bursae reduce friction. Inflamed bursa = bursitis.

Question 34

What is the effect of ageing on synovial fluid?

Answer 34

Increased viscosity. Leads to slower joint movements and redcued lubrication.

Question 35

What is the effect of ageing on cartilage water content?

Answer 35

Reduced water content - reduced shock absorption Less protection of articular surfaces -\> increased risk of damage

Question 36

Describe the effect of osteoarthritis

Answer 36