The patient is in a coma after a motor vehicle accident.In addition to IV medications,the patient is receiving an isotonic IV fluid.The primary purpose for this fluid infusion is to:

A) cause cells to shrink and reduce swelling.
B) move fluid from intravascular space into cells.
C) pull fluid from cells into the intravascular space.
D) expand the body's intravascular fluid volume.

Fluids that have the same osmolality as normal blood are called isotonic.Intravenous (IV)solutions are hypertonic,isotonic,or hypotonic.Isotonic solutions such as 0.9% sodium chloride (same osmolality as normal blood)expand the body's extracellular fluid volume without causing water to shift in or out of cells.Infusion of hypertonic intravenous solutions (more concentrated than normal blood),such as 3% sodium chloride,pulls fluid from cells by osmosis,causing them to shrink.Physiologically hypotonic solutions (less concentrated than normal blood after they are infused)move water from the extracellular compartment into the cells by osmosis,causing them to swell.