JEE Main levelSingle correct optionDifficulty 2 of 3el067
Cimetidine and ranitidine reduce acid secretion in the stomach without interfering with the allergic actions of histamine. The best explanation is that they
Abind H1 and H2 receptors with equal strength but act only in the stomach
Bbind selectively to the H2 receptors of the stomach wall, which are different from the H1 receptors responsible for allergic responses
Cdestroy histamine wherever it is present in the body
Dneutralise the hydrochloric acid already present in the stomach
Answer: B
Histamine acts through different receptor types. Acid release is mediated by H2 receptors of the stomach, which cimetidine and ranitidine block, while allergic responses are mediated by H1 receptors, which they leave unaffected.