Answer
The plasma membrane of the soma has only 50 to 75 gates per square micrometer. so it cannot produce action potentials Whereas the plasma membrane of trigger zone has 350 to 500 gates per Sq micrometer. At the nodes of ranvier ,there are 2000 to 12000 gates per squaremicrometer,this helps in Saltatory conduction .
Work Step by Step
If an excitatory local potential spreads all the way to the trigger zone and is still Strong enough when it arrives, it can open these gate general an action potential .
