mOsm stands for milliosmoles, which is a unit of measurement used to quantify the concentration of solute particles in a solution. It is often used in healthcare to measure the osmolarity of fluids in the body.
You have the osmolarity or the osmolality of the blood is equal to the RBC in your blood. That is about 154 millimole or milliosmole, with only slight variation, depending of the water consumption. So the RBC do not burst in your body. They will not burst either, in isotonic or human normal saline. That means in 0.9 % saline solution.
- 0,9 g/L NaCl equal to 0,154 moles - but because NaCl is dissociated in two ions in water the relation is 1 mol NaCl equal 2 osmol/L - and so 0,9 % NaCl equal 308 milliosmole/L