You probably see advertisements every day for shampoos and conditioners that will supposedly give you beautiful, healthy hair. If your hair is dry, there's a conditioner for that. If it's too oily, you can fix it with a shampoo. Got dandruff? You can take care of it in the shower. But the truth is that the condition of your hair could have more to do with your scalp than your realize -- you can't have healthy hair without a healthy scalp.

There are several scalp conditions that can affect the way your hair looks, and one of the most common is dandruff. Dandruff typically doesn't do anything more than lightly dust your shoulders in a thin covering of dead skin cells, but if your scalp also happens to be oily, you could end up with visible patches of dead skin in your hair. Even without dandruff, an oily scalp can be troublesome -- it can make your hair look greasy and flat [source: ISHRS]. Doing something as simple as running your fingers through your hair can make matters worse -- you could be spreading oil through your hair and mixing it with dirt and bacteria from your hand [source: Rockoff].

There are also several scalp conditions that can lead to thinning hair or even permanent hair loss. Tinea capitis is a condition that develops when your scalp becomes infected by fungi. It's generally accompanied by temporary hair loss and requires antibiotics [source: Rockoff]. Other conditions with similar side effects include alopecia areata, hair loss that occurs when the immune system attacks hair follicles, and telogen effluvium, a condition that occurs when there's a change in the number of hair follicles growing hair [source: WebMD, WebMD].

If your hair is damaged or unhealthy, try paying more attention to your scalp, and if you think you may have a scalp condition, see your doctor. For more information on how your scalp can affect your hair, see the links on the following page.