Perspiration, or sweat, is our body's way of cooling itself, whether that extra heat comes from hardworking muscles or from overstimulated nerves. Actually sweat does not "stink" like the deodorant manufacturers would like people to think. It is only after bacteria eat the sweat that their excretions "stink."
Deodorants mask the smell of body odour, which is actually caused by bacteria, where as anti-perspirants block the pores of the skin to stop us from perspiring.
There are two types of glands in our underarms, apocrine and eccrine. The eccrine glands are by far the most numerous sweat glands and are responsible for producing most of the sweat in our underarms, as well as in our entire body.
When the sweat gland is stimulated, the cells secrete a fluid that travels from the coiled portion of the gland up through the straight duct and out onto the surface of our skin.
Most antiperspirants contain aluminium chlorohydrate/ aluminium chloride or aluminium zirconium, which are highly soluble and readily absorbed into the skin. Once in the body, the aluminium passes freely across cell membrances and is readily absorbed.
The aluminium ions are taken into the cells that line the eccrine-gland ducts at the opening of the epidermis, the top layer of the skin. When the aluminium ions are drawn into the cells, water passes in with them.
As more water flows in, the cells begin to swell, squeezing the ducts closed so that sweat can't get out.
Source : The Hindu