Is saliva hypotonic to blood plasma?

Yes, saliva is hypotonic to blood plasma. This means that it has a lower osmotic pressure than blood plasma.

The osmotic pressure of a solution is determined by the concentration of dissolved particles in it. Blood plasma has a higher concentration of dissolved particles, such as ions, proteins, and glucose, compared to saliva. Therefore, blood plasma has a higher osmotic pressure than saliva.

When saliva comes into contact with blood plasma, water molecules move from the blood plasma into the saliva due to osmosis. This movement of water dilutes the saliva and increases its osmotic pressure. However, saliva remains hypotonic to blood plasma even after this dilution.