Read an Excerpt
Busy Mom's GUIDE to Parenting Teens
By PAUL C. REISSER
Tyndale House Publishers, Inc.Copyright © 2012 Focus on the Family
All right reserved.
Chapter OneBODIES IN MOTION
You created my inmost being; you knit me together in my mother's womb. I praise you because I am fearfully and wonderfully made; your works are wonderful, I know that full well. PSALM 139:13-14
From a physical standpoint, the main event of adolescence is puberty, which serves as the physiological bridge between childhood and adulthood.
Puberty: the stage of maturation in which an individual becomes physiologically capable of sexual reproduction (from the Latin puber: "adult").
Rapid growth and body changes during these years are to a large degree brought about by interactions between several hormones: biochemical compounds created in one part of the body and sent via the bloodstream to have a specific effect somewhere else in the body. These chemical messages provoke an impressive number and variety of responses. Hormones and the glands that secrete them are collectively known as the endocrine system.
Not all hormones are related to reproduction. Thyroid hormone, for example, plays an important role in the body's metabolic rate. Insulin, which is secreted by the pancreas, escorts glucose (or blood sugar) into the cells that need and use this basic fuel. Growth hormone, as its name implies, is necessary for the attainment of normal adult height.
Speaking of growth hormone, a major growth spurt is one hallmark of adolescence, usually occurring between the ages of ten and fourteen in girls, and twelve and sixteen in boys. (Perhaps "spurt" isn't the most accurate term for this event, which actually lasts between two and three years.) The rate of growth can vary, but it tends to be fastest during spring and summer. Weight increases as well, and bones progress through their final stages of maturation. In addition, the percentage of body fat increases in girls and decreases in boys.
What physical changes can I expect in my son at puberty?
Male sexual development usually begins between the ages of ten and thirteen (the average age is eleven or twelve), and the process is usually completed in about three years, though it can range anywhere from two to five years. The timing and speed of bodily changes can vary greatly between boys of the same age, and boys who develop more slowly may need extra encouragement and continued reassurance that they will eventually reach the goal of manhood. A boy should be checked by his physician if he begins to show pubertal changes before age nine or has none of these developments underway by age fourteen.
The first physical sign of puberty in boys is enlargement of the testicles and thinning of the scrotum. Hair appears under the arms, on the face and chest, and in the genital area. His voice starts to deepen, although it may pass through an awkward phase of breaking, especially when he is excited or nervous.
The testicles begin manufacturing sperm, which are transported through a structure called the epididymis (one of which sits adjacent to each testicle) and then onward to the penis through a pair of flexible tubes called the vas deferens. The prostate begins to produce seminal fluid, which carries sperm out of the body during ejaculation.
The newly functioning sexual equipment will at times carry out its functions unexpectedly during the middle of the night in what is called a nocturnal emission or "wet dream," a normal event that an uninformed adolescent might find alarming. Along the same lines, boys may be concerned or embarrassed by unexpected erections, which can occur at very inopportune times (for example, just prior to giving a report in front of a class). Neither of these events should be interpreted as a sign of impending moral failure. In fact, it's best to brief your son about these normal occurrences before puberty arrives so he's not taken by surprise.
If you are a single mother who feels uncomfortable discussing these matters with your son, consider seeking help from an adult male who not only shares your values but has enough rapport to talk with your son about these topics.
Some boys develop a small, button-sized nodule of breast tissue directly under the nipple. This is a common response to changing hormones, although it may cause a minor panic when first discovered ("Is this a tumor?" "Am I going to develop breasts like a woman?"). This area may become a little tender but should return to normal within twelve to eighteen months. If you have any questions, or if breast tissue appears to be increasing in size (a phenomenon known as gynecomastia), have it checked by your son's doctor.
What physical changes can I expect in my daughter at this stage?
While pubertal development and the reproductive process are relatively straightforward in boys, the changes that take place as a girl progresses to womanhood are in many ways much more complex. (As you will see, they also take quite a bit longer to explain.) Not only does she undergo significant changes in her outward appearance, but inside her body a delicate interplay of hormones eventually leads to a momentous occasion: her first menstrual period (also called menarche), announcing her potential to reproduce.
The first visible sign of puberty in girls is the development of breast buds, which usually appear about two years before the first menstrual period. Each breast bud is a small, flat, firm button-like nodule that develops directly under the areola (the pigmented area that surrounds the nipple). This tissue eventually softens as the breasts enlarge. Occasionally a bud will develop on one side before the other, which might lead to the mistaken impression that a tumor is growing. But the passage of time and (if necessary) a doctor's examination will confirm that this growth is normal.
As the breasts continue to develop, hair begins to grow under the arms, on the legs, and in the genital area. The contour of the hips becomes fuller, and the internal reproductive organs grow and mature. Glands within the vagina produce a clear or milky secretion, which may appear several months before the onset of menstrual bleeding.
Finally, at the conclusion of an intricate sequence of hormonal events, the first menstrual flow arrives. This typically occurs around twelve or thirteen years of age, with a range between nine and sixteen. As with boys, girls who begin this process earlier or later than average will need some information and reassurance. In general, a girl should be checked by her physician if she develops breast buds before age eight or has her first period before age nine. At the opposite end of the spectrum, the absence of pubertal changes by thirteen or menstrual periods by sixteen should prompt a medical evaluation.
What goes on in my daughter's body during the menstrual cycle?
Under normal circumstances, each month a woman's body performs a three-act play titled Preparing for a Baby. What you are about to read is a summary of the essential characters and plot. (As with many other aspects of human physiology, there are thousands of other details that will not be spelled out here and thousands more yet to be discovered. The design of this process is indeed exquisite.)
The main characters in the play are:
The hypothalamus: a multifaceted structure at the base of the brain that regulates basic bodily functions such as temperature and appetite. It also serves as the prime mover in the reproductive cycle.
The pituitary: a small, punching-bag-shaped structure that appears to dangle from the brain directly below the hypothalamus. It has been called the "master gland" because it gives orders to many other organs. But it also takes important cues from the hypothalamus.
The ovaries: a matched pair of organs in the female pelvis that serve two critical functions—releasing one or more eggs (or ova) each month and secreting the hormones estrogen and progesterone. At birth, the ovaries contain about two million eggs, a woman's lifetime supply. During childhood, the vast majority of these gradually disappear, and by the time a girl reaches puberty, only about 300,000 will be left. During a woman's reproductive years, she will release between three hundred and five hundred eggs; the rest will die and disappear.
The uterus: a pear-shaped organ consisting primarily of muscle and containing a cavity where a baby grows during pregnancy. This cavity is lined with delicate tissue called endometrium, which changes remarkably in response to the estrogen and progesterone produced by the ovaries. The uterus, also called the womb, is located at the top of the vagina and positioned in the middle of the pelvis between the bladder and the rectum.
The fallopian tubes: a pair of tubes, about four to five inches (10 to 13 cm) long, attached to the upper corners of the uterus and extending toward each ovary. Their job is to serve as a meeting place for egg and sperm and then to transport a fertilized egg to the uterus.
Act I: Preparing an egg for launch (the follicular phase). The hypothalamus begins the monthly reproductive cycle by sending a "message" called gonadotropin-releasing hormone to the pituitary gland. The message says, in effect, "Send out the hormone that prepares an egg to be released by the ovaries." The pituitary responds by secreting into the bloodstream another biochemical message known as follicle-stimulating hormone (FSH), which prepares an egg to be released by the ovaries. Each egg within an ovary is covered with a thin sheet of cells, and the term follicle (which literally means "little bag") refers to the entire package of egg and cells together. Under the influence of FSH, eight to ten follicles begin to grow and "ripen." Usually only one becomes dominant and progresses to full maturity.
This follicular phase of the cycle lasts about two weeks, during which the dominant follicle fills with fluid and enlarges to about three-quarters of an inch (2 cm). The egg contained within it will soon be released from the ovary. At the same time, this follicle secretes increasing amounts of estrogen, which (among other things) stimulates the lining of the uterus to proliferate and thicken. This is the first stage of preparation of the uterus for the arrival of a fertilized egg.
Act II: The egg is released (ovulation). As in Act I, this part of the story also begins in the hypothalamus. In response to rising levels of estrogen, the hypothalamus signals the pituitary to release a brief but intense surge of luteinizing hormone (LH) into the bloodstream. This hormone sets off a chain reaction in the ovaries. The dominant follicle enlarges, its outer wall becomes thin, and finally it ruptures, releasing egg and fluid. This mini-eruption, called ovulation, takes only a few minutes and occurs between twenty-four and forty hours after the peak of the LH surge. Sometimes a tiny amount of blood oozes from the ovary as well. This may irritate the lining of the abdomen, producing a discomfort known as mittelschmerz (German for "middle pain," because it occurs about halfway through the cycle).
Act III: The voyage of the egg and the preparation of the uterus (the luteal phase). The egg is not left to its own devices once it is set free from the ovary. At the end of each fallopian tube are structures called fimbriae (Latin for "fingers"), whose delicate tentacles move over the area of the ovary. As soon as ovulation takes place, the fimbriae gently escort the egg into the tube, where it begins a journey toward the uterus. The cells that line the fallopian tube have microscopic hairlike projections called cilia, which move in a synchronized pattern and set up a one-way current through the tube. If sperm are present in the outer portion of the tube, and one of them is successful in penetrating the egg, fertilization takes place and a new life begins.
The fertilized egg will incubate in the tube for about three days before arriving at its destination, the cavity of the uterus, where it floats for approximately three more days before implanting. Around the seventh day, it "rests," implanting in the cavity of the uterus. If the egg is not fertilized, it will live only twelve to twenty-four hours and then disintegrate or pass through the tube and uterus into the vagina. (Since sperm live for forty-eight to seventy-two hours, there are three or four days in each cycle during which intercourse could lead to conception.)
Meanwhile, a lot of activity takes place in the ovary after ovulation. The newly vacated follicle has another job to do: prepare the uterus to accept and nourish a fertilized egg should one arrive. The follicle turns into a gland called the corpus luteum (literally, "yellow body," because cells lining the inside of the follicle develop a yellowish color), which secretes estrogen and, more important, progesterone, which dominates this luteal phase of the cycle, promoting growth and maturation of the uterine lining. This layer of tissue eventually doubles in thickness and becomes stocked with nutrients. Progesterone not only prepares the uterine "nursery" for a new arrival, but also relaxes the muscles of the uterus, decreasing the chance of contractions that might accidentally expel the egg. Progesterone also temporarily stops the preparation of any other eggs within the ovaries.
If a fertilized egg successfully implants and continues its growth within the uterus, it secretes a hormone called human chorionic gonadotropin (HCG), which sends an important message to the corpus luteum: "Keep the hormones flowing!" The corpus luteum obliges and for nine or ten weeks continues to provide the hormonal support that allows the uterus to nourish the baby growing inside. After ten weeks, the placenta (the complex organ that connects the baby to the inner lining of the uterus) takes over the job of manufacturing progesterone, and the corpus luteum retires from active duty.
If there is no fertilization, no pregnancy, and thus no HCG, the corpus luteum degenerates. Progesterone and estrogen levels fall, resulting in a spasm of the blood vessels that supply the lining of the uterus. Deprived of the nutrients it needs to survive, the lining dies and passes from the uterus, along with blood and mucus, in what is called the menstrual flow (also referred to as a girl's "period" or menses).
Though the menstrual period might seem to be the end of the story, the first day of flow is actually counted as day one of a woman's reproductive cycle. For while the flow is taking place, the three-act play is starting over again as a new set of follicles begins to ripen in the ovaries. This "circle of life" will normally continue month after month throughout a girl's or woman's reproductive years, until menopause, unless it is interrupted by pregnancy or a medical condition that interferes with this cycle.
What is normal during menstrual periods?
The words menstrual and menses are derived from the Latin word for "month," which refers to the approximate frequency of this event. A typical cycle lasts from twenty-seven to thirty-five days, although for some women normal menses occurs as frequently as every twenty-one days or as infrequently as every forty-five days. Most of the variability arises during the first (follicular) phase leading up to ovulation. Assuming that a pregnancy does not begin, the luteal phase (from ovulation to menses) is nearly always fourteen days, with little variation.
For a year or two after a girl's first menstrual period, her cycles may be irregular because of anovulatory cycles, meaning an egg is not released. If ovulation does not take place, the cycle will remain stuck in the first (follicular) phase. Estrogen will continue to stimulate the lining of the uterus until some of it becomes so thick that it outgrows its blood supply. The shedding of this tissue resembles a menstrual period, but it is unpredictable and usually occurs with very little cramping. When ovulation finally takes place, the lining of the uterus will mature and then be shed all at once if a pregnancy has not started.
Excerpted from Busy Mom's GUIDE to Parenting Teens by PAUL C. REISSER Copyright © 2012 by Focus on the Family. Excerpted by permission of Tyndale House Publishers, Inc.. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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