Lecture 5

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Question 1 of 30

What stresses does cartilage resist? (3) = Compression, shear, tension

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Question 2 of 30

Other than resistance to stress, what else does cartilage provide the body? = Low friction surface for moveable joints

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Question 3 of 30

What is the composition of cartilage? = 85% water, 15% collagen, 5% proteoglycans, 5% chondrocytes

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Question 4 of 30

What are the ‘zones’ in articular cartilage? (4) = Superficial, middle, deep, calcified

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Question 5 of 30

What direction does collagen lie in the superficial zone? = Parallel to the articular surface

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Question 6 of 30

Why is collagen arranged parallel to the articular surface? = To resist shear forces

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Question 7 of 30

What proteoglycan exists in the middle zone? = Aggrecan

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Question 8 of 30

How is collagen arranged in the middle zone? = apparently random

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Question 9 of 30

How is collagen arranged in the deep zone = Perpendicular to articular surface

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Question 10 of 30

Why is collagen arranged perpendicular to the articular cartilage in the deep zone? = To strengthen the cartilage-bone bond

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Question 11 of 30

What is the tidemark? = The transition point between the deep zone and the calcified zone

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Question 12 of 30

What are the processes in the load cycle? (5) = -ve charges on proteoglycans draw ions from synovial fluid into matrix , Water follows, cartiage swells , Unloaded equilibrium once collagen is placed under tension and resists swelling. , Load place on cartilage , Loaded equilibrium when water is secreted from cartilage matrix due to pressure, -ve charges come closer together and then repel each other resisting further load

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Question 13 of 30

What causes loss of cartilage? (5) = Under use/immobilisation, excessive use, trauma, age, osteoarthritis

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Question 14 of 30

How does too much exercise cause osteroathritis? = Reduced proteoglycan content which leads to osteoarthritis

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Question 15 of 30

What does moderate exercise do to cartilage? (2) = Increases proteoglycans, thickness of cartilage

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Question 16 of 30

What are primary risk factors for osteoarthritis? (3) = Age, obesity, genetics

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Question 17 of 30

What are the secondary risk factors for OA? = Occupation (overloading), injury

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Question 18 of 30

What is the first step in the development of OA? = Collagen fibrillation

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Question 19 of 30

What follows collagen fibrillation of cartilage and what is the result? = Microfissures - network breaking

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Question 20 of 30

How does cartilage respond to microfissures, and what effect does this have? = Cells divide - cell clusters, secretion of aggrecan, increase of water (swelling)

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Question 21 of 30

What follows swelling? (2) = Loss of collagen, aggrecan causing cracks, loss to bone, and bony spurs

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Question 22 of 30

What is the final step in developing osteoarthritis? = Cells secrete cytokines (MMPs, ADAMPTs) which degrade collagen and aggrecan

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Question 23 of 30

hat markers to labs look for to ascertain OA? (3) = Collagen levels, collagen fragments, MMPs

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Question 24 of 30

What are sources of cells for tissue engineering? (3) = Autologous sources, allogenic sources, xenogeneic sources

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Question 25 of 30

What is the difference between tissue replacement and cell replacement? = Tissue replacement restores mechanical function, cell replacement restores biochemical function

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Question 26 of 30

Why does lab grown cartilage not withstand mechanical loads? = Collagen arrangement is not comparable to biological cartilage

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Question 27 of 30

Why does cartilage engineering not work for osteoarthritis sufferers? = Doesn’t solve the problem of immune cells attacking tissue.

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Question 28 of 30

What are scaffolds? = Biocompatible materials like collagen and alginate gels which encourage cells to form new ECM

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Question 29 of 30

What is needed for tissue engineering? (2) = Cells, scaffolds

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Question 30 of 30

How do tissue engineers stimulate tissue production in engineered tissue? = Mechanical stimuli that simulates loading and unloading of normal cartilage

Question 30 of 30