The loss of water and salts through the skin, and the corresponding physiological adjustments

Abstract

The practical importance of the great loss of chloride which occurs during continued sweating was clearly demonstrated in the paper contributed by Prof. K. Neville Moss, a former Tyndall Research Student, to the Royal Society in 1923 (1). He described the acute attacks of cramp (violent and very painful, particularly in the abdominal region) met with among miners, stokers, steel workers, and other men engaged in hard work in hot places when water is drunk freely. It appeared that two conditions determined the occurrence of these acute attacks. In the first place the man must quench his thirst freely by drinking ordinary water. In the second place he must at the same time be engaged in hard muscular work. It is clear that if a man is sweating, and at the same time replacing the fluid lost by drinking ordinary water, there will be a tendency, since much chloride may be lost in the sweat, for the percentage of chloride in the blood-plasma and whole body to fall, with corresponding tendency for what is at present usually called the “osmotic pressure” of the blood-plasma to fall. This tendency is, however, ordinarily met to a large extent by the action of the kidneys, which excrete the excess of water while retaining chloride which would otherwise be excreted. During hard muscular work, however, the kidneys are thrown almost out of action, as was recently shown by Pembrey and his associates (2); this being doubtless due to the blood-supply being diverted from the kidneys to muscles and skin. The body is thus left defenceless against the effects of loss of chloride, with the result that unless a good reserve of chloride is available the acute symptoms described by Moss may be produced.