Antagonist activity is the activity that is counter to the
agonist or it can be viewed as an inhibitory activity. If
pharmacology, the antagonist does not have any activity, but it
blocks or inhibits the activity of the agonist.
Any activity which is occurring outside the system ,and that
particular activity also affect the system is known as exogenous
whereas endogenous activity are those activity that occur within
the system ,and also affecting the system.