SODIUM CHLORIDE 115 



who relates that African tribes, living wholly upon vegetables, use wood 

 ashes (chiefly potassium) in place of table salt. Animals deprived of 

 salt suffer from anemia, general weakness and edema. 



Stomach and Intestines. — Salt has caused gastro-enteritis and death 

 in enormous doses. Large doses occasion emesis in dogs. Irritation of 

 the stomach is caused by withdrawal of water from the mucous mem- 

 branes by strong (hypertonic) solutions (osmotic action). This is called 

 "salt action" and is common to all salts of the alkalies. Salt in the food 

 often improves digestion — probably by bettering the taste of the food 

 and exciting the appetite and so, reflexly, stimulating the flow of gastric 

 juice, on the same principle that the sight, taste, and smell of food are 

 the chief factors in the first secretion of HCl. Salt acts in the bowels 

 as a mild hydragogue purgative. It is unfit as a cathartic for horses or 

 dogs; but is useful for cattle and sheep when combined with magnesium 

 or sodium sulphate. Salt creates thirst and, therefore, promotes the in- 

 gestion of water. A large supply of water flushes the system and removes 

 deleterious and imperfectly oxidized matters. Neither salt nor any of 

 the sodium salts are as diuretic as the potassium salts. 



Salines generally, on being absorbed into the blood, increase its 

 concentration, which causes a flow of water into the blood and increases 

 its volume. This leads to enhanced vascular tension and so to diuresis. 



In the case of sodium salts, however, elimination is so rapid from the 

 blood that they do not have time to attract water and occasion diuresis as 

 do potassium salts. When an electrolyte is introduced into the blood it 

 may act either through its ions (p. 8) or, if these are inert, by "salt 

 action." This is practically osmosis. 



If a salt is introduced into the blood, water will be drawn into the 

 vessels from the surrounding tissues until the concentration of the salt in 

 the blood is equal to that outside the vessels, or until the blood is isotonic 

 with the surrounding fluid. 



Hence a normal salt solution (0.9 per cent.) for injection into the 

 blood is also said to be isotonic or equal in concentration to that normally 

 in the blood. 



Blood. — The red corpuscles are augmented by salt. Concentrated or 

 hypertonic salt solution, containing more than 0.9 per cent., injures the 

 red cells, which become crenate and lose water; hypotonic solutions cause 

 the red cells to swell, absorb water and lose hemoglobin. 



Metabolism. — Salt solution in the blood withdraws fluid lymph from 

 the tissues by osmotic action, and stimulates protoplasmic activity, and 

 thus favors the general functioning of the tissues; hence its use in de- 

 pressed states of the system. In this way it appears to stimulate tissue 

 change, as there is an increased elimination of nitrogen in the urine. 



Summary. — Emetic, cathartic, digestive, slight diuretic, protoplasmic 

 stimulant. 



Uses External. — A solution consisting of one ounce each of salt, 

 nitre and sal ammoniac, in one quart of water, may bg. used on bruises 

 and sprains as a stimulant and refrigerant lotion. Severe hemorrhage, 

 collapse and surgical shock are treated most successfully by injections 



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