A cell swells up when kept in hypotonic solution due to the process of endosmosis. A solution having low osmotic concentration (hence, low osmotic pressure but less negative solute potential) as compared to another solution is known as hypotonic solution. When a cell kept in hyperrtonic solution it shrinks. A solution having high osmotic concentration (hence, high osmotic pressure but more negative solute potential) as compared to another solution is termed as hypertonic solution. The two solutions with the same concentration or pressure or potential are named as isotonic solutions.