Sweat Gland

Sweat glands sit in the deeper skin and connect to the surface through a duct that carries their fluid upward. The main varieties are eccrine, apocrine, and the less common apoeccrine, and they differ in where they cluster and what they secrete. Collectively they let the body shed heat and respond to emotional signals. Their number and distribution vary from person to person and across body regions, being densest on the palms and soles. The glands are supplied by nerves that trigger them, so sweating is driven by signals rather than being constant. Because they are embedded in living skin, their function can be affected by conditions of the skin and nerves around them. Each gland is anchored in the dermis, with only its narrow duct reaching up through the outer layer. The coiled shape of the base gives the gland surface area to produce fluid. When these glands work too much, too little, or not at all, the result is described by specific medical terms.

Palms and soles carry a high density of sweat glands, which is why they can feel damp even when the rest of the body stays dry. By contrast, areas like the back have fewer, more widely spaced glands, so sweat there tends to appear as a general sheen rather than concentrated beading. The type of gland also matters, since underarm glands can add smell that palm glands do not.

Specific types include the eccrine gland, apocrine gland, and apoeccrine gland, and the sweat duct carries their output outward to the skin surface.