Why does a zener diode sustain high reverse current?

[ShreyasR]

I have read that a zener diode is just a heavily doped diode. And it conducts without burn out in its breakdown region while reverse biased at its zener voltage. But why does the zener diode sustain high reverse current just because it is heavily doped? Any help is appreciated. Thank you!

 

[moj20062001]

it can undergo a breakdown if the current and voltage is high...
but befor this happens,reverse current powers up the apposing field in the middle and so it apposes the passing of the current.