GENERAL THERAPEUTICS OF THE GLANDS (DU- 

 PHORETICS AND SIALAGOGUES) 



Physiology. — The glands, especially the sweat, salivary and 

 mucous glands, are, as secretory organs, of great importance in 

 therapeutics because their physiological activity can be artificially 

 increased for curative purposes. This physiological activity con- 

 sists in the secretion of water, and also of specific and pathological 

 constituents, which are eliminated from the body with the gland 

 secretions. The secretion is the result of an active function of 

 the gland cells, which is under the influence of specific secretory 

 nerves, and is not a mere filtration. For this reason drugs acting 

 specifically upon the glands (arecoline, pilocarpine) are required 

 to artificially stimulate the gland secretion, while drugs which only 

 increase the blood-pressure (digitalis) and thereby promote filtra- 

 tion are without effect. The gland secretions are indirectly influ- 

 enced, however, by the quantity and quality of the blood and its 

 rate of flow, and also by the dilation and contraction of the blood- 

 vessels (vasomotor nervous system). 



The sweat glands are especially well developed in the horse. 

 The general sweat centre is situated in the medulla oblongata, 

 and there are also special centres for the anterior extremity in the 

 end of the cervical cord and for the posterior extremity in the 

 lumbar cord. The secretory fibres pass from the centres to the 

 sweat glands by way of the motor nerves. The secretion of sweat 

 can be increased by direct stimulation of the centres (increase of the 

 body temperature, fever, diaphoretics) or by reflex stimulation (cu- 

 taneous irritation, various thermic and electrical stimuli, increased 

 muscular activity). The most important constituents of normal 

 sweat in addition to water (97.5 to 99.5 per cent.) are urea, volatile 

 fatty acids (formic, acetic, butyric, caproic and caprylic acids) and 

 salts (sodium chloride, potassium chloride, sodium and potassium 

 phosphate, sodium and potassium sulphate and calcium, magne- 

 sium and iron compounds) . The average amount of sweat secreted 

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