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Chapter One

Your Teens

Puberty is the most tumultuous and wonderful hormonal change your body will ever go through. The Latin root of the word, pubescere, means "to become hairy, come to maturity." But this transition represents much more than the need to shave or wear a bra. Let's go over the good stuff first: You're growing breasts, getting taller, developing curves. Your reproductive organs -- your vagina, ovaries and uterus -- are maturing, which will make it possible for you to have sex when you're ready. Your periods begin, which of course will permit you to get pregnant and bear children in the future.

On the downside, these periods can be messy and cause painful cramps and moodiness. You're also growing hair in strange places (under your arms, in the pubic area). Your skin is getting oilier, and you're sprouting pimples. You perspire and develop body odor. And for some of you, weight gain is an issue.

Why is this all Happening?

It all starts with our XX sex chromosomes, which are present in the nucleus of each one of our cells and contain the instructions for our body's development. Note: The male sex is chromosomally challenged. They're missing a little piece of the second X chromosome and as a result are XYs. Only we XXs are capable of developing ovaries, which contain millions of eggs (also known as follicles) that will produce female hormones and that ultimately can be fertilized and cause pregnancy.

There are three major hormone systems that cause our bodies to change. Each system or axis is composed of a central brain control, several hormonal messengersand glands that produce additional hormones. The adrenal axis is the first to mature. At the age of eight or nine, the center of our brain, called the hypothalamus, produces a hormone that directs the brain's pituitary gland to prompt the adrenal glands (which sit on top of our kidneys) to get going. As a result, we begin to produce several malelike hormones. It's the testosteronelike qualities of these adrenal hormones that prompt so-called sweet little girls (ponytails and barrettes included) to start sweating, emitting body odor, growing body hair and developing acne. (And, oh yes, becoming interested in boys.) This phase is called the adrenarche.

The second source of hormonal upheaval is due to the activity of the somatotropic axis (soma=body, tropic=growth) and the production of growth hormone. This complicated axis interacts with many other crucial hormones such as insulin, thyroid adrenal hormones and sex hormones, and, indeed, if one of these hormones is missing, the axis is thrown off and our development may be delayed or absent. If all the hormones do their job, our organs and bones grow. During our growth spurt, we gain about three and a half inches in height every year from the time our breasts begin to develop until we get our period. Once our cycles are regular, we'll probably add just two more inches to our height, and we'll stop growing somewhere between ages 16 and 18.

This brings us to our ovarian hormones, which are produced by the follicles in our ovaries. Believe it or not , we're born with a million eggs. But they're very fragile, and more than half die before we even get to puberty. The ones that make it will slowly be stimulated and start to produce the very hormones that cause us to mature from girls to women. As we get into our teens, the hypothalamus begins to put out a hormone called GnRH (gonadotropin-releasing hormone). "Gonad" is the generic term for sex glands, in our case, ovaries.

Initially, our less-than-mature brains start to secrete GnRH in spurts during the night. With time, these pulses become steady, occurring day and night, and finally they are strong enough to cause production of another brain hormone, FSH (follicle-stimulating hormone). FSH is the final instructor for the development of our follicles, and as they mature, they produce estrogen, the hormone that will rule our development and other important aspects of our lives.

Estrogen causes our breasts to develop and contributes to our female physique, prompting fat to accumulate in our breasts, hips, thighs and derrieres. It also changes the lining of the vagina, converting it from smooth, shiny and inflexible to wrinkled, pink and pliable. At the same time, this hormone causes the uterus to mature so that its walls thicken and the glands of its cervix, or opening, produce mucus, which is secreted into the vagina. As a result, a light, yellow-tinged discharge often stains our underwear.

Even though our follicles are producing estrogen, they have not reached maturity until they produce a second female hormone, progesterone. We need critical amounts of estrogen to tell our brain that it's time to produce LH, or luteinizing hormone. LH then instructs the follicle to release the egg from the ovary (ovulation) and produce progesterone. This hormone causes the lining of the uterus to thicken and become a lush, welcoming abode for a potential pregnancy (if -- heaven forbid, at your age -- the egg is fertilized). If the egg isn't fertilized by the sperm, 14 days after its release, the leftover follicle, called the corpus luteum, collapses and dies. There's no more estrogen and progesterone to nourish the uterine lining, so it too collapses and is shed, causing a period. Our first period is so important it's been given its own name: menarche. Knowing all this will not only explain what's happening, but should also get you an A in biology!

Am I Normal?

I hate the word "normal" because it implies that those of us who don't fit into a very specific category are medical misfits in need of treatment or change.