BIOCHEM 3H03 Lecture Notes - Lecture 3: Plasma Osmolality, Synovial Fluid, Molality
19 Apr 2019
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Osmolarity = number of moles of particles/litre solution. Osmolality = number of moles of particles/kg of solvent (water) For a simple solution, there is no significant difference. For plasma -> osmolality is more appropriate. If solvent is water, osmolarity and osmolality are the same. All body fluids are aqueous: transport of nutrients and removal of waste, chemical reactions of the body are conducted in water-based buffer. Volume, constituents and concentrations must be maintained to support life; all factors are interconnected: if homeostasis is not maintained, health and life are at risk. Vast majority of body"s k is intracellular. Measuring extracellular k concentration is a poor indicator of body k status. Percent of water in human body decreases as we age. Membranes separating the various compartments are semi-permeable: permeable to water, but only semi-permeable to things dissolved in water. Small molecules (na+, k+, cl-) move across membranes.
