Sweat helps regulate body temperature, removes waste products, and protects the skin. It is produced by skin glands and mostly consists of water with minerals, lactate, and urea. The hypothalamus controls sweat glands, which are coiled tubular structures containing myoepithelial cells. There are two types of sweat glands: merocrine and apocrine, with the latter being responsible for body odor and potentially secreting pheromones.
Sweat helps keep people cool in hot weather or when exercising and is therefore an important part of thermoregulation, the maintenance of an even body temperature. By moistening the skin, the liquid cools the body as it evaporates. It also aids in the excretion or removal of waste products from the body and helps protect the skin from such environmental hazards as bacteria and chemicals. Sweat is produced by skin glands in response to temperature or other stimuli.
Sweat content is mostly water, but about 0.2-1% of the solute is made up of minerals, lactate and urea. In addition to being triggered by a rise in temperature, it can also be caused by nausea and stress. Cooling down the body typically reduces sweating.
The sweat glands in the skin are controlled by the hypothalamus in the brain, part of the autonomic nervous system. Temperature receptors in the skin influence the body’s hypothalamic, or core, temperature, which in turn sends signals to the hypothalamus. Warmed skin lowers the hypothalamic set point, or the threshold at which sweating begins. When this set point is reached, the hypothalamus sends signals to activate the glands.
These glands are coiled tubular structures in the epidermis or skin. Each contains a special type of cell called myoepithelial cells that contract when activated. This movement compresses the glands, expelling sweat directly to the skin’s surface.
Human skin contains two types of sweat glands: merocrine and apocrine. The merocrine glands are more numerous and widespread and shallower than the apocrine glands. They are found throughout the body, with the highest concentrations on the palms and soles. These glands are responsible for most of what people consider to be sweat.
Apocrine glands are found in the armpits, groin and around the nipples. They secrete a more viscous, cloudy product and become active during puberty. The presence of bacteria in these glands sometimes causes a noticeable odor, which is part of the reason why some people give off a noticeable odor when they sweat. It has been hypothesized that these glands secrete pheromones, which can potentially communicate signals to others by influencing their hormone levels.
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