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84 Cards in this Set
- Front
- Back
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what is the function of articular cartilage?
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minimises contact stresses, dissipates energy during weight bearing, allows frictionless movement between joint surfaces
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what are the cells of cartilage?
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chondrocytes
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t/f... articular cartilage has a nerve supply
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false, articular cartilage is aneural, avascular and alymphatic
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what is the function of chondrocytes?
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synthesis and catabolism of ECM
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how do chondrocytes receive nutrition?
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diffusion of nutrients from synovial fluid
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describe the matrix of articular cartilage
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polyanionic proteoglycans entrapped within a network of inextensible collagen fibres
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how is water held within the articular cartilage network?
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by the highly negatively charged proteoglycans
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what is the purpose of the high water content of articular cartilage?
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resiliency (ability to recover after deformation)
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t/f... chondrocytes are densely packed in the articular cartilage
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false, chondrocytes are sparsely distributed (10% of wet weight of tissue)
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what percentage of articular cartilage is water?
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60-80%
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t/f... synovial membrane is avascular
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false, synovial membrane is well vascularised
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t/f... osteoarthritis is accompanied by synovial inflammation
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true
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what will be the result of persistent overloading of cartilage?
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exhaustion of capasity of chondrocytes to synthesise an appropriate matrix, upregulation of catabolic process leading to proteolytic breakdown of cartilage
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t/f... depletion of proteoglycans will not affect the function of cartilage
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false
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is arthritis more common in males or females?
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females
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t/f... obesity is a risk factor for osteoarthritis
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true
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what has the strongest association with the development of OA?
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major trauma to joints and supporting ligaments
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t/f... osteoporosis is a risk factor for osteoarthritis
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false
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what inactivates the toxic metabolite of paracetamol?
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conjugation with glutathione
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what are some side effects of regular use of NSAIDs?
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dyspepsia, gastric damage, ulcers and bleeding, renal insufficiency
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why is aspirin associated with a higher degree of bleeding than other NSAIDs?
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aspirin is more potent at inhibiting platelet cyclo-oxygenase which inhibits synthesis of thromboxane A2
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which cycoloxygenase isozyme is inducible?
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COX-2
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what does cyclooxygenase do?
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converts arachodonic acid to prostaglandins
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which enzyme converts arachodonic acid to leukotrienes?
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lipoxygenase
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what is the most common inflammatory arthritis in men?
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gout
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how is uric acid produced?
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by the breakdown of purine nucleotides
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what fraction of plasma uric acid is endogenously produced?
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2/3
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what is the level of saturation for uric acid concentration in the plasma?
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0.42 mmol/L
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when do crystals of sodium urate form?
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when the uric acid level rises into the supersaturation range
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what percentage of the hyperuricaemic population grow urate crystals?
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20%
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what causes an acute attack of gout?
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interaction between crytals and inflammatory system
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t/f... joint destruction in chronic gout occurs due to intraosseous tophi and chronic synovitis
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true
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what shape are monosodium urate crystals?
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needle-shaped
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is hyperuricaemia usually due to impaired renal clearance or over production of uric acid?
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85% have impaired renal clearance, 30% overproduce
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how many solar keratoses develop into squamous cell carcinomas per year?
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1/1000
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how are SCCs treated?
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excision
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what is the most common form of skin cancer?
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basal cell carcinoma
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what type of skin cancer metastasises early?
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melanoma
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what type of skin cancer rarely metastasises?
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BCC
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what percentage of melanomas regress spontaneously?
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10%
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what are the common sites of metastasis of malignant melanoma?
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lungs, liver, brain
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where are basal cell carcinomas commonly found?
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face
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what is the usual cause of skin cancer?
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exposure to uv light
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what is the prevalence of OA?
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1 in 10
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what is the prevalence of RA?
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1 in 100
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what is the prevalence of gout?
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1 in 100
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what is the prevalence of psoriatic arthritis?
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1 in 100
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what is the prevalence of SLE?
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1 in 1000
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what is the prevalence of ankylosing spondylitis?
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1 in 200
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what is the prevalence of scleroderma?
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1 in 10000
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what percentage of people over 75 are affected by OA?
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80%
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t/f... synovial inflammation is not a feature of OA?
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false, synovial inflammation is a feature of OA though to a lesser extent than in RA
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does bone thin, thicken or stay the same in OA?
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bone thickens
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does chondrocyte apoptosis occur late or early in OA?
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early
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are osteophytes an early or late manifestation of OA?
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late
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which phenotype of OA has a distribution including the DIP joints, knees and 1st MTP?
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type 1
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which phenotype of OA has a distribution including elbows, ankles and MCPs?
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type 2
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what are the radiographic features of OA?
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osteophyte formation, joint space narrowing, subchondral sclerosis, subchondral cysts
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which OA deformity occurs at the DIPs?
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Heberdens nodes
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which OA deformity occurs at PIPs?
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Bouchards nodes
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which part of the knee is more commonly affected by OA?
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medial
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what will be observed in synovial fluid analysis in OA?
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WCC<2000 cells/ml
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what are the potentially preventable risk factors for OA?
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obesity, muscle weakness, injury and joint trauma, mechanical stress, deformity and malalignment, inflammatory disorders, endocrine and metabolic disorders
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what is the strongest independent risk factor for OA?
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increasing age
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what percentage of OA of the hands or hips is due to genetics?
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50%
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what is the most common skin cancer?
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BCC
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what are the risk factors for BCC?
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sunburns, episodic/recreational UV, genetic susceptibility, arsenic exposure, immunosuppression
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what does imiquinod do?
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stimulates an immune attack on the tumour via IFN-alpha, IFN-gamma, TNF, CD4+ T cells, IL-1,5,8,12
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what percentage of Australians over 40 have actinic keratoses?
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over 60%
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where do SCCs metastasise?
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lymph nodes, lungs, bone
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what are the risk factors for SCC?
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immunosuppression, chronic UV exposure, HPV, arsenic, genetic predisposition
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what is the usual treatment for SCC?
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excision
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what tumour thickness (melanoma) correlates with 98% 10 year survival?
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0.5 mm
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what tumour thickness (melanoma) correlates with a 62% 10 year survival?
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4mm
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what are the risk factors for melanoma?
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recreational UV, sunburns, UV early in life, chronic UV, large numbers of naevi, genetic predisposition, pale skin, immunosuppression
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t/f... there is no evidence that sunscreens reduce melanoma
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true
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which pathway of purine nucleotide synthesis promotes uric acid production?
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de novo pathway
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which pathway of purine nucleotide synthesis inhibits uric acid production?
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salvage pathways
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what converts xanthine to uric acid?
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xanthine oxidase
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what are tophi?
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extracellular deposits of uric acid
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what converts allopurinol to alloxanthine?
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xanthine oxidase
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how does allopurinol inhibit xanthine oxidase
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alloxanthine remains bound at the active site
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what converts uric acid to allantoin?
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uricase
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what is the disadvantage of benzbromarone?
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hepatic toxicity
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