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Importance of Electrolytes
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Importance of Electrolytes

The main function of blood plasma electrolytes is the creation of osmotic pressure. Posm = 7,5 atm (0,3 osmole, 745 kPa, 5600 mmHg). The osmotic pressure is defined by the quantity of solved particles, not by the size of them. 96% of the osmotic pressure is made by Na+ and Cl- ions, because the molecular mass of NaCl is small.

Solutions, the osmotic pressure of which is the same as blood plasma has, are called isotonic. For example, 0,9% solution of NaCl, Ringer’s solution, Ringer-Lock’s solution, Tirode, 5% glucose solution, haemodesis. Solutions with the osmotic pressure of which is higher than the plasma is called hypertonic, if it is lower it is called hypotonic.

In hypertonic solution water is leaving the cells, cells firm, their normal turgor is disbalanced. It is called plasmolysis. In clinics it is used for counting the erythrocytes: blood is diluted by 4% solution of NaCl, erythrocytes are firmed and they are easy to count.

In hypotonic solution water enters cells, cells swell, oedema of the cells occurs and destruction of the cells, which is called haemolysis. In both cases cells metabolism disorder occurs or even can lead to the death of the cell.

           Plasmolysis                                             Haemolysis

 

Figure 1.4 – Plasmolysis and haemolysis in erithrosyts 



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