Illustrated · 1 min
Due to osmosis, when cells have different levels of salt within than outside of the cell, water moves to decrease the difference. When salt levels are equal, there is no issue and the surrounding solution is called isotonic. When there is more salt externally (hypertonic solution), cells lose water and shrink. When there is more salt in the cell than outside (hypotonic solution), cells swell with water and may even burst.
