NREMT Paramedic Practice

What receptors do antihistamines primarily block?

1. H2 receptors

2. Beta receptors

3. Dopamine receptors

4. H1 receptors

The correct answer is: H1 receptors

Antihistamines primarily block H1 receptors, which are a specific type of histamine receptor involved in allergic responses. When histamine is released during an allergic reaction, it binds to H1 receptors on various tissues, leading to symptoms such as itching, swelling, and vasodilation. By blocking these receptors, antihistamines inhibit the action of histamine, thereby alleviating symptoms associated with allergic reactions, such as hay fever, urticaria, and other forms of allergies. The other types of receptors, such as H2 receptors, are mainly involved in regulating gastric acid secretion, while beta receptors play critical roles in the sympathetic nervous system, affecting heart rate and bronchodilation. Dopamine receptors are involved in various neurological processes. Therefore, they do not relate to the action of antihistamines, making the H1 receptor the correct target for these medications.