BPS 334 Lecture Notes - Lecture 48: Renal Sodium Reabsorption, Nephron, Plasma Osmolality
Document Summary
Fluid and electrolyte disorders: disorders of sodium, water, and potassium. 1/3 of body water is extracellular of extracellular water (1/12 of total body water) is in the blood vessels (the arterial, venous and capillary systems) called extracellular intravascular fluid. Of remaining extracellular/extravascular water is called extracellular interstitial fluid. In body water, range from large mw (immunoglobulins to low mw (h+ ions). They are cations (na+, k+, ca++), anions (cl-, hco3-, proteins) or neutral. Sodium (na+): restricted to the extracellular compartments (extracellular conc: 140 meq/l) Potassium (k+): restricted to the intracellular compartment by the enzyme na+/k+/atpase (intracellular conc: 4 meq/l. **na+/k+ atpase: facilitates na+ entry into extracellular space and k+ entry into cells. Sum of all solute particles per volume of fluid compartment. Although each of the fluid compartments contain different types of solutes, the osmolality of each compartment is the same. This occurs because compartments are separated from each other by membranes that are freely permeable to water.