The two sides of a nerve cell membrane have unequally distributed ions ( Na+ and K+). Sodium is inside, while potassium is outside. Carriers actively transport them. This active transport mechanism is called Sodium-Potassium Pump. Without stimulus, sodium channels are closed while some of the potassium channels are open.
Stimulus (depolarization) will cause the sodium channels to briefly open and the positively-charged ion diffuses into the nerve cell. The membrane potential becomes positive. The potassium channels open and positively-charged potassium diffuse out. With respect to the outside, the inside will become less positive again.
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Eukarya
Eukarya consists of Protista, plantae, fungi, and anomalies. Kingdom Protista consists of eukaryotic organisms that are primarily unicellular and other, simple multicellular relatives, such as slime mold or algae
Used for energy by mammals
