to give new life or vigor to
Hair is made up of dead cells
Hair is made up of dead cells and keratin. Because it is made up of dead cells, unlike when you damage other parts of your body (like getting a cut in your skin), your hair cannot repair itself. Therefore, technically, hair cannot be "revitalized." When it becomes damaged, it remains damaged. And new damage builds upon the older damage. This explains why the newest hair — the hair closest to the scalp — is the healthiest hair, while the hair at the ends — the hair that has had been exposed the longest — is the most damaged. But just because you can't 'heal' hair, it doesn't mean caring for your hair isn't important!
Why is hair care important?
While hair is technically "dead," hair care is very important. But why? If you have a plant that dies, there's no point in continuing to water it. Why is hair different? To understand this, rather than compare hair care to care for living organisms like plants, consider the importance of caring for your clothing. Like hair, your clothes aren't alive of course. But if you have a beautiful dress, you want to wear it proudly for as long as possible. So how do you care for it? You store it in your dark closet rather than outside, to minimize the damage that it would be exposed to in the rain, sunshine, dust and other elements. When you have to wear it in the rain, you protect it with a raincoat. When it needs to be washed, you spend extra time and money to take it to a professional dry cleaning facility, where the cleaning process will be gentler on the garment than tossing it in the washing machine at home.
Likewise, to keep beautiful hair, steady and daily maintenance is critical to minimize the inevitable damage it will incur. This is especially true for those who lighten their hair with bleaches and peroxides. It's also especially true for those who keep their hair long. (Remember what we said about the hair that is the farthest from your scalp is going to be the most damaged.)
The hair is dead, but is the hair root alive?
Yes. Hair begins its lifespan inside what is called the follicle. At that point, it is composed of living cells. But this is hair underneath the scalp and not visible, while the hair that has grown out doesn't have any active cells and is therefore technically dead. The hair shaft contains dead keratinized cells. This is why not only is hair care important, but so is scalp care! But we will save that for another blog entry.