A. True Due to excessive reabsorption of water from the collecting ducts of the nephron.
B. False Water is drawn into cells from the hypotonic extracellular fluid; water intoxication may occur.
C. True People sweating heavily may replace their water, but not their salt, deficit; they tend to get muscle cramps unless they supplement their salt intake.
D. True Sodium ions are responsible for nearly half of plasma osmolality.
E. False The hypothalamic osmoreceptors responsible for thirst respond to hypertonicity, not hypotonicity of the ECF.
