How do the guard cells regulate opening and closing of stomatal pores?

Explanation

Each stomatal pore is surrounded by two guard cells that assist in stomatal opening driven by turgidity of guard cells. The guard cells are the only epidermal cells with unevenly thickened walls and chloroplasts. When water flows in guard cells from epidermal cells, guard cells become turgid and stomata are opened. Loss of water from guard cells makes them flaccid and stomata are closed.