Explain the cellular effects of water deprivation (dehydration) on the body's fluid compartments.

This text explains the cellular effects of water deprivation (dehydration) on the body's fluid compartments:

1. When the body loses water (e.g., through sweat, urine, respiration) and doesn't replace it, water is initially drawn from the extracellular fluid (ECF) compartment, which is the fluid outside the cells. This reduces the ECF volume slightly and, more importantly, increases the concentration of solutes in the ECF, making it hypertonic (more concentrated) compared to the fluid inside the cells (intracellular fluid or ICF).

2. Due to this difference in concentration, water then moves by osmosis (the movement of water across a semi-permeable membrane from an area of higher water concentration to an area of lower water concentration) from the intracellular compartments (inside the cells) into the now more concentrated ECF.

3. As cells lose water to the ECF, they shrink in size. This cellular dehydration can impair normal cell function.