- Sweat glands, also known as sudoriferous glands, are specialized exocrine glands found throughout the skin that play a crucial role in thermoregulation, waste excretion, and maintaining skin hydration.
- They are an integral part of the integumentary system and are responsible for producing sweat, a clear fluid composed primarily of water, electrolytes (especially sodium and potassium), urea, and small amounts of lactic acid and other metabolic by-products. Humans possess millions of sweat glands, and their function is vital to maintaining homeostasis and protecting the body from overheating.
- There are two primary types of sweat glands: eccrine glands and apocrine glands.
Eccrine sweat glands are the most numerous and are distributed widely across nearly all skin surfaces, with especially high concentrations on the palms, soles, forehead, and axillae. These glands open directly onto the skin surface and produce a watery, odorless sweat primarily for cooling the body. When the body temperature rises, the hypothalamus triggers eccrine glands via the sympathetic nervous system (cholinergic pathways) to secrete sweat. As this fluid evaporates from the skin surface, it dissipates heat, reducing body temperature. Eccrine sweat also contributes to skin hydration and has mild antimicrobial properties. - Apocrine sweat glands, on the other hand, are located mainly in areas rich in hair follicles such as the axillae, groin, and around the nipples. These glands become active during puberty and secrete a thicker, milky fluid into hair follicles rather than directly onto the skin. Unlike eccrine sweat, apocrine secretions are rich in proteins and lipids and, while initially odorless, they are broken down by skin bacteria, leading to body odor. Apocrine glands are also believed to play a role in pheromone signaling, although their exact role in human social or sexual communication is not fully understood.
- Sweat gland activity is influenced by temperature, emotions, and hormones. Emotional stress can activate both eccrine and apocrine glands, particularly in the palms, soles, and underarms, leading to nervous sweating. Hormonal changes during puberty and menstruation can also affect sweat production and odor.
- Several disorders are associated with sweat gland function. Hyperhidrosis is a condition characterized by excessive sweating, often localized to specific areas such as the hands, feet, or underarms, and can significantly impact quality of life. It may be primary (idiopathic) or secondary to other conditions such as hyperthyroidism, diabetes, or infection. Conversely, anhidrosis or hypohidrosis refers to reduced or absent sweating, which may lead to heat intolerance or heatstroke, especially in hot environments. Certain skin infections or systemic illnesses, such as diabetes neuropathy, can impair sweat gland function. Additionally, genetic disorders like ectodermal dysplasia can result in malformed or nonfunctional sweat glands.
- In clinical and cosmetic contexts, sweat glands are often targeted for various treatments. For example, botulinum toxin injections are used to temporarily inhibit sweat production in cases of severe hyperhidrosis. Antiperspirants, which contain aluminum-based compounds, act by blocking the sweat gland ducts. Research into sweat biomarkers is also ongoing, as sweat can provide non-invasive insights into a person’s hydration status, electrolyte balance, and even disease markers.
