We care about cleaning it. We care about beautifying it. We care about keeping it in some places and losing it in others. Just as skin can shine and glow, so can your locks—as long as you use the right tactics to maintain your mane.
Your Hair: Losing It and Abusing It
In today's world, we don't treat our hair all that well. In fact, if your hair knew what was going on, it would be pulling its hair out.
To show you how, let's talk about the structure of hair—how it grows, how it can end up in your shower drain, and how it can end up looking about as lively and healthy as sun-scorched grass. The average person's head has up to 150,000 hair follicles (the adult body has 5 million). That number is constant over a lifetime; it's hereditary, so only thickness, condition, and whether you lose the actual strands that come from those follicles can change. Each one of those strands grows about six inches a year—women between the ages of 16 and 24 pump it out the fastest.
While it may seem that your hair is as far removed from your internal organs as your clothes or jewelry, each strand of hair has its own blood supply. Because of that, hair is greatly influenced by health and diet. Hair is also under the delicate control of hormones, which is why men have beards and hair on their chests and male-pattern baldness on their heads, and women don't.
As you can see in Figure 2.1, [not pictured] your hair is made up of distinct structures: the follicle and the shaft. A tunnel-like segment in the epidermis portion of your skin, the follicle resides under the surface of the skin and extends down into the dermis. The base of the follicle contains little blood vessels that nourish the cells. The living part is the bulb at the base, while the shaft—the part of the hair that we see above the skin—is dead.
That hair shaft is made up of a protein called keratin. The inner layer (the medulla) and the middle layer (the cortex) make up the majority of the shaft. Like the nail's structure, the hair's cuticle, which looks like a tile roof under the microscope, serves as the outer, protective layer that covers the medulla and cortex.
Now, to keep your hair shiny, it needs oil. Surrounding your hairs are tiny muscles that give you goose bumps, standing your hairs on end when you're cold or during a scary movie. These muscles also squeeze the glands that lube up your hair, which produce sebum—your own natural vitamin E–rich hair and skin conditioner.
How Hair Is Lost
When it comes to hairy situations, many of us can live with a bad haircut or a little graying or the occasional day when our hair looks like a haystack. But the most frustrating problem for many people—men especially—is what's perceived to be the start of the downhill slide to death, or at least the impetus for wanting that Corvette: hair loss.
While we tend to say that baldness comes from the mother's side, an individual's genes from both parents influence that person's predisposition to male-- or female--pattern baldness. Of course, hair loss is far more visible in men (80 percent of whom experience some degree of baldness), but nearly 40 percent of women lose substantial amounts of hair after menopause, as well (women tend to thin out all over, rather than develop the signature spots that men do), making it a major appearance issue for both genders.