In
humans, sweating is primarily a means of thermoregulation, although it has been
proposed that components of male sweat can act as pheromonal cues.Evaporation
of sweat from the skin surface has a cooling effect due to the latent heat of
evaporation of water. Hence, in hot weather, or when the individual's muscles
heat up due to exertion, more sweat is produced. Sweating is increased by nervousness
and nausea and decreased by cold. Animals with few sweat glands, such as dogs,
accomplish similar temperature regulation results by panting, which evaporates
water from the moist lining of the oral cavity and pharynx. Primates and horses
have armpits that sweat similarly to those of humans.Sweat glands are innervated
by the sympathetic nervous system; however, because the primary neurotransmitter
involved with the innervation of sweat receptors is acetylcholine, and many
of the glands are under the control of the hippocampus via nerve pathways typically
thought of as parasympathetic. The nerve terminal releases acetylcholine, which
binds to M3 receptors on the sweat gland and causes the secretion of sweat.
Acetylcholine is partially degraded by Cholinesterase enzyme (AchE); thus anything
which interferes with AchE activity causes too much sweating.(1)
source
: wikipedia