MSK

Question 1

What are the proteoglycans bound to in the ECM?

Answer 1

The GAGs (Glycosaminoglycans)

Question 2

Which type of collagen is found in cartilage?

Answer 2

Type II. Type I is found in the skin, bone and eyes.

Question 3

Which dietary cofactor for prolyl hydroxylase and lysine hydroxylase is required for the synthesis of collagen?

Answer 3

Vitamin C (ascorbic acid). Scurvy is caused by a Vit C deficiency.

Question 4

Which enzyme type degrades collagen?

Answer 4

The matrix metalloproteinases (MMPs).

Question 5

Ehlers-Danlos syndrome can be caused by a mutation in which of the collagen sub-classes?

Answer 5

Type I, III or V.

Question 6

What is Fibrillin?

Answer 6

A microfibril which surrounds elastin cores. A mutation in Fibrillin 1 causes Marfan’s syndrome.

Question 7

Which is the major proteoglycan found in articular cartilage?

Answer 7

Aggrecan.

Question 8

Which is the only non-sulphated GAG and the major molecule responsible for synovial fluid viscosty?

Answer 8

Hyaluronic acid

Question 9

Defne the three classes of joint. 1) Synarthroses 2) Amphiarthroses 3) Diarthroses

Answer 9

1) Suture lines, where adjoining plates of bone are separated by thin tissue 2) Bones bound by flexible cartlage, as in the pubis symphsis, sacro-iliac joints etc. 3) Synovial joints, subdvided into many, such as ball and socket, hinge, saddle, plan

Question 10

“Osteogenesis imperfecta describes a variety of conditions which are mostly autosomal ________. They have variable phenotypic severity and >___% have a mutation in one of collagen type I genes”

Answer 10

1- dominant 2- 90%

Question 11

What might you notice in the eyes of a patient with osteogenesis imperfecta?

Answer 11

Blue sclera.

Question 12

Ehlers-Danlos type VI is an autosomal recessive condition that is caused by a defect in which enzyme?

Answer 12

Lysyl hydroxylase.

Question 13

What is Gorlin’s sign?

Answer 13

The ability to touch the nose with the tongue. This is NOT diagnostic for EDS.

Question 14

What is the most common cause of death in Marfan’s syndrome?

Answer 14

Dissection of the descending thoracic aorta.

Question 15

MMPs are calcium dependent endopeptidases that require what metal to function?

Answer 15

Zinc

Question 16

What does ADAMTS stand for?

Answer 16

A Disintegrin And Metalloproteinase with ThromboSpondin motifs. It is an aggrecanase.

Question 17

Cathepsin K is a cysteine protease most active in what sort of environment? a) Basic pH b) Acidic pH c) Low temperatures d) High temperatures e) If “The Chain” by Fleetwood Mac is being played

Answer 17

Acidic pH.

Question 18

Cathepsin K is a protease involved in what major process?

Answer 18

Bone remodelling. Osteoclasts express high levels of Cathepsin K.

Question 19

There are two types of synoviocyte, A and B. What do they do?

Answer 19

Type A are macrophage-like and are phagocytic. Type B are fibroblast-like and produce hyaluronate.

Question 20

TNF-a is the dominant pro-inflammatory cytokine in RA. What cell is it released by?

Answer 20

Activated macrophages.

Question 21

What must you screen for before treating RA with antibody Rx and why?

Answer 21

TB. The antibody used is to TNFa (eg. Infliximab). TNFa is critical for host defence against TB.

Question 22

RANKL is produced by T cells and synovial fibroblasts in RA. What does it act to do?

Answer 22

Stimulate osteoclast formation

Question 23

Excessive load and/or abnormal joint components can lead to the development of what pathology?

Answer 23

Osteoarthrits.

Question 24

In OA, new osteophytes are often laid down in the inter-phalangeal joints. What are their eponymous names?

Answer 24

At the DIPs: Heberden’s nodes

At the PIPs: Bouchard’s nodes

Question 25

Name structure 1

Answer 25

I Band

Question 26

Name structure 2

Answer 26

H Zone

Question 27

Name structure 3

Answer 27

CapZ

Question 28

Name structure 4

Answer 28

Titin

Question 29

Name structure 5

Answer 29

Z disc

Question 30

Name structure 6

Answer 30

Myosin head

Question 31

Name structure 7

Answer 31

Myosin tail

Question 32

Name structure 8

Answer 32

Actin filament

Question 33

Name structure 9

Answer 33

M Band

Question 34

Which complex of 3 structures bind calcium, exposing myosin head binding sites on the actin filaments?

Answer 34

Troponin.

Question 35

Myophosphorylase can cause subsarcolemmal accumulation of ___________

Answer 35

Glycogen. There is no glycogen phosphorylase activity due to a mutation in the PYGM gene.