TY - CHAP M1 - Book, Section TI - Sodium and Water Composition and Physiology A1 - Mount, David B. A2 - Jameson, J. Larry A2 - Fauci, Anthony S. A2 - Kasper, Dennis L. A2 - Hauser, Stephen L. A2 - Longo, Dan L. A2 - Loscalzo, Joseph PY - 2018 T2 - Harrison's Principles of Internal Medicine, 20e AB - Water is the most abundant constituent in the body, comprising ~50% of body weight in women and 60% in men. Total-body water is distributed in two major compartments: 55–75% is intracellular (intracellular fluid [ICF]), and 25–45% is extracellular (extracellular fluid [ECF]). The ECF is further subdivided into intravascular (plasma water) and extravascular (interstitial) spaces in a ratio of 1:3. Fluid movement between the intravascular and interstitial spaces occurs across the capillary wall and is determined by Starling forces, i.e., capillary hydraulic pressure and colloid osmotic pressure. The transcapillary hydraulic pressure gradient exceeds the corresponding oncotic pressure gradient, thereby favoring the movement of plasma ultrafiltrate into the extravascular space. The return of fluid into the intravascular compartment occurs via lymphatic flow. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accesspharmacy.mhmedical.com/content.aspx?aid=1178487085 ER -