regulated by neural and hormonal mechanisms (men sweat more than women). When all of the eccrine sweat glands are working at maximum capacity, the rate of perspiration for a human being may exceed three liters per hour, and dangerous losses of fluids and electrolytes can occur. Eccrine glands have three primary functions: Thermoregulation: sweat (through evaporation and evaporative heat loss) can lead to cooling of the surface of the skin and a reduction of body temperature. Excretion: eccrine sweat gland secretion can also provide a significant excretory route for water and electrolytes. Protection: eccrine sweat gland secretion aids in preserving the skin's acid mantle, which helps protect the skin from colonization from bacteria and other pathogenic organisms. Apocrine Apocrine sweat glands are found in the armpit, areola (around the nipples), perineum (between the anus and genitals), in the ear, and the eyelids. The secretory portion is larger than that of eccrine glands (making them larger overall). Rather than opening directly onto the surface of the skin, apocrine glands secrete sweat into the pilary canal of the hair follicle. Before puberty, the apocrine sweat glands are inactive; hormonal changes in puberty cause the glands to increase in size and begin functioning. The substance secreted is thicker than eccrine sweat and provides nutrients for bacteria on the skin: the bacteria's decomposition of sweat is what creates the acrid odor. Apocrine sweat glands are most active in times of stress and sexual excitement. In mammals (including humans), apocrine sweat contains pheromone-like compounds to attract other organisms within their species. Study of human sweat has revealed differences between men and women in apocrine secretions and bacteria. Apoeccrine Some human sweat glands cannot be classified as either apocrine or eccrine, having characteristics of both; such glands are termed apoeccrine. They are larger than eccrine glands, but smaller than apocrine glands. Their secretory portion has a narrow portion similar to secretory coils in eccrine glands as well as a wide section reminiscent of apocrine glands. Apocrine, found in the armpits and perianal region, have ducts opening onto the skin surface. They are presumed to have developed in puberty from the eccrine glands, and can comprise up to 50% of all axillary glands. Apoeccrine glands secrete more sweat than both eccrine and apocrine glands, thus playing a large role in axillary sweating. Apoeccrine glands are sensitive to cholinergic activity, though they can also be activated via adrenergic