physiology of sweating

Last reviewed 03/2023

There are three main types of eccrine gland sweating:

• thermoregulatory sweating
• emotional sweating
• gustatory sweating

Sweat is formed by active secretion deep within the dermis. Its composition is initially near to that of plasma but with minimal protein. During passage along the sweat duct, reabsorption of sodium and chloride ions occurs until their concentrations are less than half of their plasma values e.g. 60mmmol and 50 mmol respectively. Conversely, potassium is secreted to give a value of 7-8 mmol in sweat.

The control mechanism for sweat secretion is both neural - cholinergic fibres of the thoracolumbar sympathetic nervous system descending from the anterior hypothalamus - and hormonal - adrenaline. If the rate of production is high, excessive amounts of solute may be lost and so aldosterone stimulation is triggered. As well as its renal reabsorption role, it also enhances sodium and chloride reabsorption along the duct of the sweat gland.