One of the greatest anatomical questions is this: how does hair grow? With your entire body covered with it, you can't help but marvel how your coat develops, how you tend to lose a lot of hair in a day, yet don't end up bald--unless you're suffering from a hair loss problem. Today, you will know the answer.

The first thing you need to know is that the hair doesn't grow at the same time. There are a lot of factors that can cause the difference. These include heredity, age, ethnicity, and even medication.

Regardless, the hair starts in the hair follicles. These are the "pouches" that are found underneath your skin. There are thousands of hair follicles in your body. However, not all of them produce hairs. Only 80 percent of them do. The rest are considered to be dormant, not working, or asleep.

Nevertheless, there are times when they become active again. When this happens, they push the old hairs out of the follicles to give way for new hairs to grow. This also explains why you could see a lot of falling hair even when you're not taking a bath.

When you have a hair loss problem called alopecia, your immune system will consider any growth on your follicles to be an attack to your defenses. Hence, before they can even develop, your hairs are already "cut off" and prevented from growing back.