| 释义 |
water potential
water potential[′wȯd·ər pə‚ten·chəl] (physiology) The difference in free energy or chemical potential (per unit molal volume) between pure water and water in cells and solutions. See Diffusion Pressure Deficitwater potential, suction pressure
water potential, suction pressure or (formerly) diffusion pressure deficit (DPD)the tendency of a cell to draw in water from outside by OSMOSIS, the water moving from a higher to a lower water potential. Since pure water at one atmosphere has a water potential of zero, cells drawing in water have a water potential of less than zero. Thus water potential is measured as a negative value, which can be confusing. Readers should be careful when using the terms ‘higher’ or ‘lower’ water potential; ‘more negative’ or ‘less negative’ are more exact statements In mathematical terms water potential is the sum of the OSMOTIC POTENTIAL and the PRESSURE POTENTIAL of a cell: For example, when Osmotic Potential = -9 and Pressure Potential = 4, Water Potential = - 9 + 4 = - 5. see OSMOREGULATION. |