Water in the human body: An anesthesiologist's perspective on the connection between physicochemical properties of water and physiologic relevance.

The unique structure and multifaceted physicochemical properties of the water molecule, in addition to its universal presence in body compartments, make water a key player in multiple biological processes in human physiology. Since anesthesiologists deal with physiologic processes where water molecules are critical at different levels, and administer medications whose pharmacokinetics and pharmacodynamics depend on interaction with water molecules, we consider that exploration of basic science aspects related to water and its role in physiology and pharmacology is relevant to the practice of anesthesiology. The purpose of this paper is to delineate the physicochemical basis of water that are critical in enabling it to support various homeostatic processes. The role of water in the formation of solutions, modulation of surface tension and in homeostasis of body temperature, acid-base status and osmolarity, is analyzed. Relevance of molecular water interactions to the anesthesiologist is not limited to the realm of physiology and pathophysiology. Deep knowledge of the importance of water in volatile anesthetic effects on neurons opens a window to a new comprehensive understanding of complex cellular mechanisms underlying the practice of anesthesiology.