MSK Flashcards
What are the proteoglycans bound to in the ECM?
The GAGs (Glycosaminoglycans)
Which type of collagen is found in cartilage?
Type II. Type I is found in the skin, bone and eyes.
Which dietary cofactor for prolyl hydroxylase and lysine hydroxylase is required for the synthesis of collagen?
Vitamin C (ascorbic acid). Scurvy is caused by a Vit C deficiency.
Which enzyme type degrades collagen?
The matrix metalloproteinases (MMPs).
Ehlers-Danlos syndrome can be caused by a mutation in which of the collagen sub-classes?
Type I, III or V.
What is Fibrillin?
A microfibril which surrounds elastin cores. A mutation in Fibrillin 1 causes Marfan’s syndrome.
Which is the major proteoglycan found in articular cartilage?
Aggrecan.
Which is the only non-sulphated GAG and the major molecule responsible for synovial fluid viscosty?
Hyaluronic acid
Defne the three classes of joint. 1) Synarthroses 2) Amphiarthroses 3) Diarthroses
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
“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”
1- dominant 2- 90%
What might you notice in the eyes of a patient with osteogenesis imperfecta?
Blue sclera.
Ehlers-Danlos type VI is an autosomal recessive condition that is caused by a defect in which enzyme?
Lysyl hydroxylase.
What is Gorlin’s sign?
The ability to touch the nose with the tongue. This is NOT diagnostic for EDS.
What is the most common cause of death in Marfan’s syndrome?
Dissection of the descending thoracic aorta.
MMPs are calcium dependent endopeptidases that require what metal to function?
Zinc
What does ADAMTS stand for?
A Disintegrin And Metalloproteinase with ThromboSpondin motifs. It is an aggrecanase.
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
Acidic pH.
Cathepsin K is a protease involved in what major process?
Bone remodelling. Osteoclasts express high levels of Cathepsin K.
There are two types of synoviocyte, A and B. What do they do?
Type A are macrophage-like and are phagocytic. Type B are fibroblast-like and produce hyaluronate.
TNF-a is the dominant pro-inflammatory cytokine in RA. What cell is it released by?
Activated macrophages.
What must you screen for before treating RA with antibody Rx and why?
TB. The antibody used is to TNFa (eg. Infliximab). TNFa is critical for host defence against TB.
RANKL is produced by T cells and synovial fibroblasts in RA. What does it act to do?
Stimulate osteoclast formation
Excessive load and/or abnormal joint components can lead to the development of what pathology?
Osteoarthrits.
In OA, new osteophytes are often laid down in the inter-phalangeal joints. What are their eponymous names?
At the DIPs: Heberden’s nodes
At the PIPs: Bouchard’s nodes
Name structure 1
I Band
Name structure 2
H Zone
Name structure 3
CapZ
Name structure 4
Titin
Name structure 5
Z disc
Name structure 6
Myosin head
Name structure 7
Myosin tail
Name structure 8
Actin filament
Name structure 9
M Band
Which complex of 3 structures bind calcium, exposing myosin head binding sites on the actin filaments?
Troponin.
Myophosphorylase can cause subsarcolemmal accumulation of ___________
Glycogen. There is no glycogen phosphorylase activity due to a mutation in the PYGM gene.
