sweat glands participate in thermoregulatory sweating, which is directly controlled by the hypothalamus. Thermal sweating is stimulated by a combination of internal body temperature and mean skin temperature. In eccrine sweat glands, stimulation occurs via activation by acetylcholine, which binds to the gland's muscarinic receptors. Emotional Emotional sweating is stimulated by stress, anxiety, fear, and pain; it is independent of ambient temperature. Acetylcholine acts on the eccrine glands and adrenaline acts on both eccrine and apocrine glands to produce sweat. Emotional sweating can occur anywhere, though it is most evident on the palms, soles of the feet, and axillary regions. Sweating on the palms and soles is thought to have evolved as a fleeing reaction in mammals: it increases friction and prevents slipping when running or climbing in stressful situations. Gustatory Gustatory sweating refers to thermal sweating induced by the ingestion of food. The increase in metabolism caused by ingestion raises body temperature, leading to thermal sweating. Hot and spicy foods also leads to mild gustatory sweating in the face, scalp and neck: capsaicin (the compound that makes spicy food taste "hot"), binds to receptors in the mouth that detect warmth. The increased stimulation of such receptors induces a thermoregulatory response. Antiperspirant Unlike deodorant, which simply reduces axillary odor without affecting body functions, antiperspirant reduces both eccrine and apocrine sweating. Antiperspirants, which are classified as drugs, cause proteins to precipitate and mechanically block eccrine (and sometimes apocrine) sweat ducts. The metal salts found in antiperspirants alters the keratin fibrils in the ducts; the ducts then close and form a "horny plug". The main active ingredients in modern antiperspirants are aluminum chloride, aluminum chlorohydrate, aluminum zirconium chlorohydrate, and buffered aluminum sulfate. On apocrine glands, antiperspirants also contain antibacterial agents such as trichlorocarbanilide, hexamethylene tetramine, and zinc ricinoleate. The salts are dissolved in ethanol and mixed with essential oils high in eugenol and thymol (such as thyme and clove oils). Antiperspirants may also contain levomethamphetamine Pathology Some diseases of the sweat glands include: Fox-Fordyce disease The apocrine sweat glands become inflamed, causing a persistent, itchy rash, usually in the axillae and pubic areas. Frey's Syndrome If the auriculotemporal nerve is damaged (most often as a result of a Parotidectomy), excess sweat can be produced in the rear of the cheek area (just below the ear) in response to stimuli that cause salivation. Heatstroke When the eccrine glands become exhausted and unable to