The inside of red blood cells is 300 mosm. what will happen to your red blood cells if you become dehydrated and your blood osmolarity increases to 350 mosm?

The dehydration can cause the loss of water from the blood plasma. As the loss of water occurs, the osmolarity of the plasma is increased. Due to the increase in the osmolarity of the plasma, the blood cell would become hypotonic with respect to plasma.

This would result in loss of water molecules from the blood cells. So, the red blood cell would lose water molecules and will shrink.