http://slideplayer.com/4385586/14/images/20/In+the+previous+picture%2C+just+look+at+the+number+of+blue-dot+particles+%28ignore+the+charges%29.+There+are+more+blue+dots+outside+of+the+cell%2C+so+there+is+a+chemical+gradient+for+the+blue+dots+to+move+inside+of+the+cells.+Insert+a+voltage+rod+to+inject+positive+charges+into+the+cell.+The+negative+charge+of+the+blue+dots+will+want+to+enter+the+cell+because+they+are+attracted+to+the+positive+charges+there.+Thus%2C+there+are+two+reasons+why+these+blue+dots+will+quickly+enter+the+cell.+But+when+will+the+blue+dots+stop+going+into+the+cell+They+will+be+attracted+to+the+positive+charge%2C+but+if+they+are+all+inside%2C+the+chemical+concentration+gradient+makes+them+want+to+diffuse+out+of+the+cell.+When+the+electrical+and+chemical+gradient+is+equally+powerful+%28in+opposite+directions%29%2C+that+is+the+Nernst+potential%3A+No+net+gain+or+loss.+Cells+with+resting+membrane+potential+are+at+minus+70mV.+They+are+not+at+their+resting+K+potential.+If+you+open+more+K+channels+than+just+the+leak+channels%2C+there+will+be+more+movement+of+K+out+of+the+cell%2C+and+the+potential+will+get+closer+to+minus+94+mV+%28at+which+time%2C+the+cell+will+reach+equilibrium%2C+and+the+cell+will+die%3B+but+the+body+does+not+let+it+get+that+far%29..jpg