Drug Toxicity And Adverse Effects Practice Test

A 70-year-old man is hospitalized for a pulmonary embolism and started on a continuous intravenous infusion of an anticoagulant. Five days later, his platelet count drops from 250,000/mm³ to 40,000/mm³. A new thrombus is noted in his right leg despite being on anticoagulation. The development of this condition is caused by antibodies directed against a complex of the anticoagulant and which of the following endogenous molecules?

A 32-year-old pregnant woman at 10 weeks' gestation is being managed for chronic hypertension. Her physician reviews her medications and decides to switch her antihypertensive agent due to significant risks to the fetus, particularly in the second and third trimesters. Disruption of which of the following fetal systems is the primary concern with her current class of medication?