A receptor can directly open the channel and exerts an ionotropic effect. The ionotropic effect takes place by the help of ionotropic receptors. These receptors are membrane bound receptor proteins which responds by the bonding of the ligand.
Due to ligand binding the channel opens and allows the movement of ions into the cells which helps in either increasing or decreasing the action potential.
The receptors can also bind to the ligand and produce metabotropic effect which means by the second messenger.
