Dr. Mark K. Williams, Ph.D. Biochemist The human body has a narrow range for maintaining optimal fluid levels, which it regulates by two sets of receptors that detect blood volume and cellular fluid [1]. Every cell is bathed in extracellular fluid (outside the cell), and intracellular fluid (inside the cell). Both fluids maintain a balance of osmolytes – low-molecular-weight organic compounds that influence the properties of biological fluids. Osmolytes manage the levels of i