Preparation of isotonic solution

Since osmotic pressure is not a readily measurable quantity, it is usual to make use of the relationship between the colligative properties and to calculate the osmotic pressure from a more easily measured property such as the freezing point depression. In so doing, however, it is important to realise that the red blood cell membrane is not a perfect semi-permeable membrane and allows through small molecules such as urea and ammonium chloride. Therefore, although the quantity of each substance required for an isotonic 

Effect Co-transport of glucose and sodium induces a bloodward osmotic fbw of water, which drags along additional ions. ORT exactly replaces water, sodium and other ions bst from the blood but does not reduce the extent or duration of diarrhoea. 

Effect Solution is unacceptable because osmotic flow yields a net loss of water and ions from the blood - an osmotic penalty. Dehydration and risk of death increase. 

Effect Each polymer has the same osmotic effect as a single glucose or amino acid molecule but markedly enhances nutrient-induced sodium transport when the polymer is broken apart at the villus cell surface. (Rapid uptake at the surface avoids an osmotic penalty.) Water and ions are returned to the blood quickly, and less of both are bst in the stool. 

Glucose-induced or amino acid-induced sodium transport 

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The recovery of narcotine from aqueous solution at varying pH values by ether extraction 38) and its solubility in a number of solvents 39) have been reported. The preparation of isotonic solutions has also been described 40). 

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