Answer:
Role of trigger zone:
Trigger zone may be defined as the area present between the junction of cell body, axon and axon hillock. This is the area where chemically regulated and voltage regulated gate meets. The depolarization of cell and propagation of action potential occur at this area.
Summation:
Summation may be defined as the additive effect of the electrical impulse on the junction between the muscle cell and nerve cell. The individual stimuli cannot generate a response, but they together can generate an action potential.
