The specific molecular changes that occur when a drug binds to a particular target site or receptor are referred to as

Drug action.

Explanation:

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.

really dont know just need some points

the major parts of the digestive system:

salivary glands.

pharynx.

esophagus.

stomach.

small intestine.

large intestine.

rectum.

accessory digestive organs: liver, gallbladder, pancreas.