­You are about to do something really big -- maybe ­a job interview, a presentation, a first date or your wedding -- and you notice that your palms and underarms are sweating. Perhaps, you've just completed an aerobic workout and your whole body is drenched in sweat. How can such different activities have the same effect on your body? What is sweat and why do we make it?

Perspiration, or sweat, is your body's way of cooling itself, whether that extra heat comes from hardworking muscles or from overstimulated nerves. In this article, we will examine your body's sweat glands, how sweat is made and what it does. You will learn that there is difference between the sweat on your palms and the sweat in your armpits and why your skin tastes salty after a workout!

The Sweat Gland
The average person has 2.6 million sweat glands in their skin! Sweat glands are distributed over the entire body -- except for the lips, nipples and external genital organs. The sweat gland is in the layer of skin called the dermis along with other "equipment," such as nerve endings, hair follicles and so on. Figure 1 illustrates what's going on:

diagram of skin
Figure 1

Basically, the sweat gland is a long, coiled, hollow tube of cells. The coiled part in the dermis is where sweat is produced, and the long portion is a duct that connects the gland to the opening or pore on the skins's outer surface. Nerve cells from the sympathetic nervous system connect to the sweat glands. There are two types of sweat glands:

Fun Fact
 Did you know that the lining of your outer ear has modified apocrine glands called ceruminous glands? These modified sweat glands produce ear wax. Ear wax is thought to prevent foreign material from entering your ears, including insects.

  • Eccrine - the most numerous type that are found all over the body, particularly on the palms of the hands, soles of the feet and forehead
  • Apocrine - mostly confined to the armpits (axilla) and the anal-genital area. They typically end in hair follicles rather than pores.
The two glands differ in size, the age that they become active and the composition of the sweat that they make. Compared to apocrine glands, eccrine glands:
  • are smaller
  • are active from birth (Apocrine glands become active only at puberty)
  • produce a sweat that is free of proteins and fatty acids

In the next section, we'll find out how the glands produce sweat.