What is osmosis, how does it help regulate the movement of water in the body.
Osmosis is the movement of water across a semi-permeable membrane. A semi-permeable membrane is a membrane that some stuff, like water, can pass through but other stuff, like large proteins, cannot.
It works through a concentration gradient. If a blood cell has a higher concentration of water inside of it than there is in the fluid outside of it, then water will leave the cell. If the fluid outside the cell has a higher concentration of water in it than inside the cell, then water will move into the cell.