SBA — Single Best Answer · Review
Question 374
Pathology → General
Classification
Question
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Two arachidonic-acid-derived inflammatory mediators are being compared. Mediator X promotes vasodilatation and increased vascular permeability, whereas mediator Y promotes smooth-muscle contraction and leucocyte chemotaxis. Which pairing is most consistent with these actions?
Question Stem
Select the single best answer.
Options
A
X = prostacyclin; Y = leukotrienes
B
X = leukotrienes; Y = prostacyclin
C
X = bradykinin; Y = prostacyclin
D
X = complement; Y = histamine
E
X = substance P; Y = serotonin
Explanation
Prostacyclin is associated with vasodilatation and increased vascular permeability, whereas leukotrienes are associated with smooth-muscle contraction and chemotaxis.
Option Validity
B) This reverses the actions attributed to prostacyclin and leukotrienes.
C) Bradykinin is associated with smooth-muscle contraction and is not the prostacyclin mediator described for X.
D) Complement participates in chemotaxis, but this pairing does not match the two specified arachidonic-acid-derived mediator profiles.
E) Substance P is particularly associated with pain, and this pairing does not reproduce the stated actions.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 5: Pathology. General Pathology, pp.161–175.