Water transport is tightly regulated by various factors, including osmotic gradients, hormonal signals, and the expression of aquaporins. In the kidneys, for instance, the hormone vasopressin increases the permeability of the collecting ducts to water, facilitating reabsorption and concentrating urine. Additionally, changes in osmolarity of the extracellular fluid can trigger cellular responses to either uptake or release water, maintaining cell volume and function.
