If a healthy 70 kg man loses 2 L of sweat while doing yard work and simultaneously drinks 2 L of pure water, which of the following body fluid changes would be expected? A) An increase in extracellular osmolarity B) An increase in extracellular fluid (ECF) volume C) An increase in intracellular osmolarity D) An increase in intracellular fluid (ICF) volume E) An increase in plasma Na⁺ concentration

Question

Quizplus · Accepted Answer

Sweat is hypotonic compared to body fluids, meaning it has a lower concentration of solutes (like sodium) than the fluids inside the body. When a person sweats, they lose more water than solutes, which decreases the extracellular fluid (ECF) volume and increases the extracellular osmolarity. Drinking pure water replenishes the lost water, increasing the intracellular fluid (ICF) volume. The water moves from the extracellular space (where it was consumed) to the intracellular space to balance the osmolarity between the two compartments, leading to an increase in ICF volume.

If a Healthy 70 Kg Man Loses 2 L of Sweat