Reasons for Resting Membrane Potential (RMP) generation -

1. Efflux of potassium ions from ICF (intra cellular fluid) into ECF (extra cellular fluid) via K+ leaky channels

2. Na-K ATPase pump that pumps 3Na+ ions out and 2K+ ions in

Reason for depolarisation - Rapid influx of Na+ ions into the cell due to opening of Na+ voltage gated channels

Reason for repolarisation - Efflux of K+ ions into ECF from ICF via K+ ion gates

Reason for hyperpolarisation - Extra efflux of K+ ions into ECF as K+ ion gates remain open for a comparatively longer time