structure and function of joints

Question 1

what do joints do? (3)

Answer 1

1. transmit load
2. allow movement
3. provides stability

Question 2

what are the three main classes of joints? (6)

Answer 2

1. fibrous joints - immobile (synarthrosis)
2. cartilaginous joints - slightly mobile (amphiarthosis)
3. synovial joints - freely mobile (diartrhosis)

Question 3

what are examples of fibrous joints? (2)

Answer 3

skull sutures, tooth sockets

Question 4

what is an example of a cartilaginous joint?

Answer 4

intervertebral disc (annulus fibrous surrounds the nucleus pulpous)

Question 5

example of synovial joints

Answer 5

limb joints

Question 6

saddle joint movement done by… (synovial joints)

Answer 6

carbo-metacarpal, base of thumb

Question 7

examples of synovial joint movements

Answer 7

simple hinge joint, complex hinge joint, pivot joints, saddle joints, ball and socket

Question 8

what is a property of ball and socket joints?

Answer 8

most mobility but least stability

Question 9

5 ways to achieve stability of a joint

Answer 9

1. needs to be congruity
2. fibrous capsule provides more stability
3. intra-articular ligaments
4. packing improves congruity
5. muscle acting across joint improves stability drastically.

Question 10

properties of articular cartilage

Answer 10

avascular and aneural - sol takes longer to repair itself

Question 11

how does the cartilage get nutrients?

Answer 11

through the synovial fluid from the synovium.

Question 12

what are the stretch receptors used for?

Answer 12

proprioception

Question 13

what do stimulation of nociceptors by arthritic effusion cause?

Answer 13

reflex muscle inhibition - overtime leads to muscle wasting in arthritis

Question 14

whats the main chemical that gives cartilage its properties?

Answer 14

GAG - glucosamine-glycan chain

Question 15

GAG + core protein =

Answer 15

proteoglycan (AGGRECAN)

Question 16

what does aggrecan do?

Answer 16

produces a huge osmotic pressure that inflates cartilage with water (gel swelling pressure)

Question 17

what does hyaluronan do

Answer 17

tethers the aggrecan molecules together

Question 18

what type of collagen fibres hold everything together?

Answer 18

type 2

Question 19

Whats the only cell type in cartilage?

Answer 19

chondrocytes

Question 20

what do chondrocytes do?

Answer 20

produces,

1. collagen
2. proteoglycans
3. hyaluronan

Question 21

how are the nutrients in the synovial fluid pushed into the cartilage?

Answer 21

diffusion

Question 22

what types of synoviacytes help secrete hyaluronon an lubricant?

Answer 22

type B

Question 23

what other cells are sometimes there in synovial lining?

Answer 23

macrophages

Question 24

what provides fluid drainage

Answer 24

synovium on the outside has interstitial matrix and there is contact between the interstitial matrix and synovial fluid.

Question 25

what is a property of plasma

Answer 25

ultrafiltrate

Question 26

what is the electrolyte and plasma protein content of synovial fluid similar to?

Answer 26

other interstitial fluids

Question 27

what is lubricin

Answer 27

glycoprotein | high load and low velocity (boundary lubrication)

Question 28

hyaluronan (3)

Answer 28

non sulphated GAG high load and low velocity (hydrodynamic lubrication) buffers fluid loss from joints

Question 29

what is joint effusion

Answer 29

when fluid increase 10 - 100x in arthritis

Question 30

how is the pressure in extension?

Answer 30

sub atmospheric (fluid enters) (synovial fluid is made)

Question 31

how is the pressure in flexion?

Answer 31

above atmosphere (fluid is driven out) (goes into lymphatic drainage)

Question 32

how does the rate of fluid loss change with hyaluronan?

Answer 32

fluid drainage (on flexion) in absence of hyaluronan is much higher than when hyaluronan is present.

Question 33

what is arthritis

Answer 33

inflammation of joint

Question 34

what is arthritis characterised by (3)

Answer 34

1. pain 2. swelling 3. loss of movement

Question 35

what are the two types of arthritis

Answer 35

1. acute | 2. chronic (immune mediated, degenerative, e.g. osteoarthritis)

Question 36

properties of osteoarthritis (3)

Answer 36

1. metabolic changes in joint, evidence of cartilage loss 2. associated with again, mechanical dysfunction, obesity 3. can be synovial inflammation

Question 37

properties of inflammatory arthritis (3)

Answer 37

1. cytokines and other inflammatory mediators released by synovium 2. autoimmune mechanism (rheumatoid) 3. damage of cartilage by inflammatory response