antihistamine. Antihistaminic Pharmacology An agent that counteracts the effects of histamine released during allergic reactions by blocking histamineâH 1 receptors Adverse effects Dry mouth, drowsiness, urine retention in â, tachycardia.hile the term antihistamine can broadly include any agent that blocks any histamine receptor, in practice it is usually used to denote those blocking the H 1 type of receptors (H1 receptor antagonists), those involved in allergic reactions.
While all of these Military service branches are uniformed, have. weapons, ranks and other such details that are. similar, the specific missions and focus of. each service is quite different. The US Army is charged as the primary land. combat force.
Service Branches Compared. As the oldest branch of the U.S. Military, the Army protects the security of the United States and its resources. The Army Reserve trains part time near home until needed, and members deploy alongside the Army.