Final answer:
Diphenhydramine targets H1 receptors and is used to treat allergic reactions and other ailments like insomnia and motion sickness. It does not interact with H2 receptors.
Step-by-step explanation:
Diphenhydramine's Mechanism of Action
Diphenhydramine acts on histamine H1 receptors. It is classified as an H1-antihistamine, which means it works by binding to H1 receptors in various parts of the body, including mast cells, smooth muscle, and the endothelium. This action is specifically designed to treat allergic reactions such as itching, runny nose, and sneezing, as well as other conditions like insomnia and motion sickness. On the other hand, H2-antihistamines, which are different from diphenhydramine, target the H2 receptors primarily found in the upper gastrointestinal tract and are used to manage conditions related to gastric acid like peptic ulcers and acid reflux.
In the context provided, diphenhydramine does not act on H2 receptors. Therefore, the correct answer is that it binds to the H1 receptors only and not H2. So, when referring to diphenhydramine, it's associated with histamine H1-receptor antagonism, emphasizing its role in allergic response management.