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[L. perspirare, breathe through]

1. The secretion of the sweat (sudoriferous) glands of the skin; SEE: sweating.
2. The salty fluid secreted through the sweat glands of the skin; sweat. Essentially, the fluid is a weak solution of sodium chloride, but it also contains potassium, lactate, and urea.
Perspiration is a means of removing heat from the body. Evaporation of 1 L of sweat removes 580 kcal of heat from the body. Sweat loss varies from 100 to 1000 mL/hr but may exceed those amounts in a hot climate.

Perspiration is increased by temperature and humidity of the atmosphere, exercise, pain, nausea, nervousness, mental excitement, dyspnea, diaphoretics, and shock. It is decreased by cold, diarrhea, other causes of profound dehydration, and using certain drugs.

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