Action potential is initiated at the Axon Hillock - Initial segment of the neuron because
The axon hillock contains the highest density of Na+-VGCs.....Hence it is a low threshold trigger zone. Synaptic input located close to the trigger zone is more effective in depolarizing and hyperpolarizing it than synaptic inputs of equal strength located fuher away. Ref guyton and hall textbook of medical physiology 12/e pg 543 and 59
Threshold for excitation is lowest
Neurotransmitter is released at this site
It is an unmyelinated segment
Has lowest concentration of voltage gated sodium channels
General physiology