Drug action can be defined, in short, as the action of the drug on the body. The effects of almost all drugs are a consequence of their interaction with macrocellular components of the body. These interactions modify the function of the relevant component and thereby initiate the biochemical and physiological changes that characterize the response or reaction to the drug. Receptors are cellular structures that have a specific purpose and that are activated in their action by different substances.
Gamma rays because microwaves, visible light and radio waves wouldn’t come in handy if an astronomer would want to study the composition of planets and stars.
