Sudoriferous glands are small, coiled tubular structures located deep within the dermis layer of the skin. Humans possess approximately two to four million glands distributed across nearly the entire body surface. Their ability to produce sweat is essential for maintaining the body’s internal stability.
Eccrine and Apocrine Glands
Eccrine glands are the most numerous, found in high concentrations on the palms of the hands, soles of the feet, and the forehead, but are otherwise distributed across almost all skin surfaces. These glands feature a duct that opens directly onto the skin’s surface through a sweat pore. The sweat they produce is a clear, watery substance composed primarily of water and sodium chloride, along with trace amounts of other electrolytes.
The apocrine glands, by contrast, are limited to specific regions of the body, including the axilla (armpit), groin, and areola. Unlike eccrine glands, their ducts generally empty into the canal of a hair follicle, releasing sweat onto the skin surface via the hair shaft. Apocrine glands are inactive until hormonal changes trigger their function during puberty.
Their secretion is thicker and more viscous, containing lipids, proteins, and ammonia. The fats and proteins in the sweat serve as a nutrient source for bacteria that naturally reside on the skin. As these surface bacteria metabolize the organic compounds, they produce volatile, malodorous waste products, which is the source of characteristic body odor.
Essential Roles of Sweat Production
The most prominent function of sudoriferous glands is the regulation of internal body temperature. When the body’s core temperature rises due to exercise or a warm environment, the eccrine glands are stimulated to produce sweat. This watery fluid reaches the skin surface and evaporates, drawing heat away from the skin and underlying blood vessels, thereby lowering the body temperature.
Eccrine sweat production also serves a minor role in excretion. The secretion contains trace amounts of metabolic waste, such as urea and lactic acid, which are eliminated from the body. Additionally, sweating helps maintain the skin’s protective acid layer and contributes to hydrating the outer layer of the skin, while moisture on the palms and soles aids friction and grip.
Sweating can also be categorized by its trigger, differentiating between thermal and emotional responses. Thermal sweating, which is widespread, is controlled by the hypothalamus and primarily involves eccrine glands responding to heat. Emotional sweating, often referred to as “stress sweat,” is localized to areas like the palms, soles, and axilla and is triggered by feelings of stress, anxiety, or pain. Both eccrine and apocrine glands can be involved in this stress response.
When Sweat Glands Malfunction
One common disorder is hyperhidrosis, characterized by sweating beyond the amount needed for normal temperature regulation. This condition primarily affects the eccrine glands due to an overstimulation of the nerves that trigger sweat production. Hyperhidrosis is classified as either primary, meaning it has no underlying cause, or secondary, resulting from a separate medical condition or medication.
The opposite condition is anhidrosis or hypohidrosis, representing the inability or decreased ability to produce sweat. Since evaporative cooling is the body’s main heat-dissipation mechanism, a failure in sweat production poses a serious danger. Individuals with this condition face a significantly elevated risk of overheating, heat exhaustion, and potentially life-threatening heatstroke. Causes can range from nerve damage to certain skin disorders or medications.
Another condition related to gland function is bromhidrosis, the medical term for persistent, excessive body odor. This often originates from the apocrine glands, where the bacterial breakdown of the lipid-rich sweat causes a strong, unpleasant smell. Eccrine sweat can also contribute by creating a moist environment that encourages bacterial growth.