Joint Physiology

Question 1

what are the 3 main types of joint in the body

Answer 1

synovial
fibrous
cartilaginous

Question 2

what are fibrous joints

Answer 2

bones united by fibrous tissue
doesn’t allow movement
example: skull bones

Question 3

what are cartilaginous joints

Answer 3

bones united by cartilage
allow limited movement
example: intervertebral discs, pubic symphysis

Question 4

what are synovial joints

Answer 4

bones separated by a cavity (containing synovial fluid)

united by a fibrous capsule

Question 5

what is the inside of the fibrous capsule in the synovial joint lines with

Answer 5

synovial membrane

Question 6

what is the synovial membrane

Answer 6

vascular connective tissue with capillary networks and lymphatics

Question 7

what do synovial cells produce and where are they found

Answer 7

synovial fluid

found in the synovial membrane

Question 8

what is a simple synovial joint

Answer 8

joint with one pair of articulating surfaces

Question 9

what is a compound synovial joint

Answer 9

more than one pair of articulating surfaces eg. elbow

Question 10

what is the role of joints during purposeful motion

Answer 10

stress distribution

confer stability

Question 11

what are the functions of synovial fluid

Answer 11

lubricated joint
facilitates joint movement- reduces friction
minimises wear and tear
Aids nutrition of articular cartilage
supplies chondrocytes with O2 and removes CO2 and waste products

Question 12

the synovial fluid is a static pool true/false

Answer 12

false

it is continuously replenished and absorbed by the synovial membrane

Question 13

what gives synovial fluid its high viscosity

Answer 13

the presence of hyaluronic acid (mucin) produced by synovial cells

Question 14

where are the other constituents of synovial fluid derived from

Answer 14

dialysis of blood plasma

Question 15

how does rapid movement change viscosity and elasticity of synovial fluid

Answer 15

decreased viscosity
increased elasticity

(this doesn’t work in diseased joints eg. osteoarthritis)

Question 16

what does normal synovial fluid look like

Answer 16

clear and colourless liquid

Question 17

the synovial fluid WBC count increases/decreases in inflammatory and septic arthritis

Answer 17

increases

Question 18

when does the synovial fluid turn red

Answer 18

in traumatic synovial tap and haemorrhage arthritis

Question 19

what does synovial fluid from a severely inflamed joint look like

Answer 19

thin and opaque

Question 20

what are the main functions of articular cartilage

Answer 20

prevents wear and tear

distributes the contact pressure to subchondral bone

Question 21

what zones make up articular cartilage

Answer 21

superficial, middle, deep, calcified

Question 22

what type of cartilage is the articular cartilage

Answer 22

usually hyaline

it is elastic with sponge-like qualities

Question 23

what is the articular cartilage ECM made up of

Answer 23

predominantly water (70%)
20% collagen (mainly type 2) 
proteoglycans (10%)

Question 24

what happens to cartilage water content with age

Answer 24

decreases with age

Question 25

what do the proteoglycans do

Answer 25

responsible for compressive properties associated with weight baring

Question 26

what cells synthesise, organise and degrade the cartilage ECM

Answer 26

chondrocytes

Question 27

how do the articular cartilage cells get nutrients and O2

Answer 27

via the synovial fluid as they are avascular

Question 28

what happens when there is a change in the amounts of the 3 major components of cartilage (water, collagen and proteoglycans)

Answer 28

the mechanical properties of cartilage would change and joint disease would occur is the rate of ECM degeneration exceeds the rate of its synthesis

Question 29

what are catabolic factors in cartilage matrix turnover

Answer 29

segregation of the cartilage matrix | proteolytic enzymes are stimulated and proteoglycan synthesis is inhibited

Question 30

what do anabolic facts in cartilage matrix turnover do

Answer 30

stimulate proteoglycan syntehsis and contract the effects of IL1 (a catabolic factor)

Question 31

what are two markers of cartilage degradation

Answer 31

serum and synovial keratin sulphate (increased levels) increased levels of type 2 collagen (Indicated cartilage breakdown)

Question 32

what is osteoarthritis

Answer 32

when cartilage and synovial composition and function deteriorate with age/ wear and tear

Question 33

what happens in rheumatoid arthritis

Answer 33

synovial cell proliferation and inflammation

Question 34

what happens when there are uric acid crystals in the joints

Answer 34

gouty arthritis

Question 35

what is soft tissue rheumatism

Answer 35

injury and inflammation to periarticular structures