Electronics can easily flow from the p-type base to the n-type collector as long as the base-emitter junction is forward biased (meaning the base is at a higher voltage than the emitter).
In a way, a transistor is like a variable, adjustable resistor.
Four modes: Saturation (short circuit), cut-off (open circuit), active (current from collector to emitter is proportional to current flowing into the base), reverse-active (like active except current flowing in reverse)
Voltages from base to emitter (Vbe) and base to collector (Vbc) set the transistor's mode.
|Reverse active||Vc < Vb < Ve|
|Saturation||Ve < Vb, Vc < Vb; Vc must be slightly greater than Ve|
|Cut-off||Ve > Vb, Vc > Vb|
|Forward active||Vc > Vb > Ve|