Although much is known about the effects of changes in electrolyte and water balance on serum sodium concentration, the quantitative relationships between body composition and the concentration of sodium in serum have not been established. Also, no definitive study has been made of the correspondence between serum sodium concentration and total serum osmolarity. It is [...]

Evolution has provided an elaborate network of regulatory systems that stabilize body-fluid volume, temperature and composition. This stability insulates cells from an ambient hostile world and assures them the best possible conditions in which to function optimally. When one of these regulatory systems fails, cells and even whole organ systems cannot function properly. This paper [...]

The chronology of hemoconcentration and hemodilution associated with changes in posture, and the reliability of venous hematocrit (Hct), hemoglobin (Hb), and plasma proteins (PP) as indicators in evaluating changes in plasma volume were determined in seven male subjects. Red cell mass was also measured by the CO method at the termination of the erect and supine positions. Movementto and from supine and erect positions produced consistent, rapid, and progressive changes in Hct, Hb, [...]