What is istotonic?

Answer 1

We generally use the term "tonic" when referring to the effects of osmosis across a real biological membrane. Osmosis is the movement of water across a membrane. We usually have osmosis when the concentration of solutes on each side of the membrane are different so water diffuses from the side with lower solute concentration to the side with higher concentration and this usually continues until we have equilibrium and no more water diffuses across. This environment is called an isotonic environment. ("iso" is Greek for similar or equal)