The intracellular fluid concentration is 300 mOsm/kg. The extracellular fluid concentration is 280 mOsm/kg. The net movement of water is in which direction?
To determine the net movement of water, we need to compare the osmolarity (concentration of solutes) of the intracellular fluid (ICF) and the extracellular fluid (ECF). In this case, the ICF concentration is 300 mOsm/kg, while the ECF concentration is 280 mOsm/kg.
Water moves across cell membranes in response to osmotic gradients, from areas of lower solute concentration to areas of higher solute concentration. This movement aims to equalize the concentrations.
Since the concentration of solutes is higher in the ICF (300 mOsm/kg) compared to the ECF (280 mOsm/kg), water will move from the ECF into the ICF in an attempt to dilute the higher solute concentration. Hence, the net movement of water is from the extracellular fluid into the intracellular fluid.