491. Regarding the veins of the lower limb
A. thrombosis in superficial veins is a common source of emboli.
B. phlegmasia alba dolens is associated with iliofemoral vein thrombosis.
C. greater than 20% of thrombotic events originate in the superficial veins of the knee and below.
D. dermatitis is a common sequel of Buerger’s disease.
E. varicosity development has no genetic component.

492. With regard to embolism
A. arterial emboli most often lodge in the viscera.
B. pulmonary emboli are rarely multiple.
C. amniotic fluid emboli are assoCiated with the highest mortality rate.
D. most pulmonary emboli produce clinical signs of respiratory distress.
E. all emboli consist of either gas or solid intravascular mass.

493. Pulmonary embolism
A. leads to pulmonary infarction in 15% of cases.
B. must occlude 25% of the pulmonary circulation to cause acute right heart failure.
C. is generally symptomatic.
D. is the cause of death in 40-50% of hospitalised patients.
E. is most commonly due to hereditary hypercoagulable states.

494. Septic shock may cause all of the following EXCEPT
A. myocardial depression.
B. vasoconstriction.
C. disseminated intravascular coagulation.
D. acute renal failure.
E. acute respiratory distress syndrome.

495. T Lymphocytes
A. are capable of cytotoxic activity.
B. are activated in the presence of soluble antigen.
C. are the basis for type II hypersensitivity.
D. differentiate into antibody producing plasma cells.
E. contain CD3 proteins with a variable antigen binding region.

496. All of the following are primary mast cell mediators during type I hypersensitivity EXCEPT
A. histamine.
B. platelet activating factor.
C. eosinophil chemotactic factor.
D. heparin.
E. tryptase.

497. Type II hypersensitivity reactions
A. involve cell mediated immune responses.
B. include serum sickness as an example.
C. explain many transfusion reactions.
D. involve IgE on mast cells.
E. explain the tuberculin skin test.

498. Passive immunity is achieved by administering
A. live virus.
B. attenuated virus.
C. adsorbed toxin.
D. activated T cells.
E. all of the above.

499. The majority of HI VIA IDS cases are reported from
A. homosexual males.
B. IV drug users.
C. haemophiliacs.
D. recipients of blood products.
E. heterosexual contact.

500. Dysplasia
A. is a feature of mesenchymal cells.
B. inevitably progresses to cancer.
C. is characterised by cellular pleomorphism.
D. is not associated with tissue architectural abnormalities.
E. is the same as carcinoma in situ.