eccrine gland
Meaning of eccrine gland: The sweat gland that covers nearly the whole body and does the actual work of cooling it.
Definition of eccrine gland
An eccrine gland is a small sweat gland that opens directly onto the surface of the skin through its own pore. These glands are spread across nearly the whole body and are densest on the palms, soles and forehead. The watery, salty sweat they release cools the body as it evaporates from the skin.
How does one work?
Each gland is a coiled tube deep in the skin with a duct running up to the surface. The coiled part filters a fluid out of the blood that is close to plasma in composition. As that fluid travels up the duct, salt is reabsorbed back into the body, so what reaches the surface is dilute and mostly water. Nerves control the process, and unusually for this branch of the nervous system they use acetylcholine as the messenger rather than adrenaline. That is why medicines blocking acetylcholine produce a dry mouth and reduced sweating together.
How does it differ from the other kind of sweat gland?
| Feature | Eccrine | Apocrine |
|---|---|---|
| Where | Almost the whole skin surface | Armpit, groin, around the nipple |
| Opens onto | The skin surface directly | A hair follicle |
| Secretion | Watery and dilute | Thicker, with fats and proteins |
| Active from | Birth | Puberty onward |
| Main role | Cooling | Scent signaling |
Body odor comes mainly from the apocrine gland, and even there the smell is produced by skin bacteria breaking the secretion down rather than by the secretion itself. Fresh eccrine sweat is close to odorless.
What controls sweating?
Two separate triggers exist. Thermal sweating is controlled by the hypothalamus, the part of the brain that monitors core temperature, and it recruits glands across the trunk and limbs. Emotional sweating is driven by stress and shows on the palms, soles and forehead, which is why hands turn clammy under pressure. Evaporation is what actually removes heat, so sweat that drips off carries away almost none of it, and cooling becomes inefficient in humid air.
What goes wrong with them?
Excessive sweating, called hyperhidrosis, usually affects palms, soles and armpits and can interfere with work and handwriting. Too little sweating leaves the body unable to shed heat and raises the risk of heat illness; it occurs with certain inherited conditions, with nerve damage and with some medicines. Blocked ducts trap sweat beneath the skin and produce the small itchy bumps of heat rash. A gland of this type is also the origin of several uncommon skin tumors.
Also known as
Used in a sentence
The biopsy showed a tumor arising from eccrine gland structures within the dermis.
Good to know
Cooling depends on sweat evaporating, so in humid air sweat that runs off the skin removes almost no heat despite the fluid being lost.
Word origin
Where “eccrine gland” comes from
From the Greek ek-, meaning out, and krinein, meaning to separate or to secrete.