Dr. Ruth K. Westheimer - Sex For Dummies

During sexual excitement, a woman experiences several physical changes:

The vaginal lips and clitoris swell.

The nipples on her breasts become erect.

The vaginal walls fill with blood in a process called vasocongestion , which is similar to the way blood flows into the penis during erection.

The vagina becomes lubricated, or slippery, by the passage of fluids through the vaginal walls. This lubrication isn’t manufactured by a gland, but occurs when fluid filters into the vagina from blood vessels surrounding it. The vasocongestion causes increased pressure that, in turn, causes the fluid within the blood serum to be pushed through the tissues of the vaginal wall.

This fluid has another function besides making it easier for the penis to slide in and out of the vagina. It also changes the chemical nature of the vagina, making it more alkaline and less acidic, an environment that proves more hospitable to sperm.

In most mammals, the female doesn’t provide any lubrication; instead, the male secretes the lubricant, similar to what the Cowper’s gland in human males produces, but in much greater quantities. Researchers have noted that, when males of certain species, such as horses, get aroused, a steady stream of this fluid flows out of the penis.

The vagina goes through several changes in a woman’s life.

Before puberty, the vaginal walls are thinner and the vaginal tube is smaller, which is one reason that so much damage can be done to a young girl who is sexually abused.

During puberty, the vagina grows, and hormones cause other changes to take place. The vagina becomes elevated, firm, and erect when a woman becomes sexually aroused.

After menopause (which I explain very soon, so be patient), a woman’s hormonal levels go down, and the vaginal tissue becomes more fragile and less elastic. A woman’s natural lubrication also declines at this time. Luckily, you have ways to treat all these problems so that they don’t affect good sexual functioning.

At the top of the vagina is the cervix , which is the entrance to the uterus. The cervix is actually the lower portion of the uterus, and it protrudes approximately one-third of an inch into the vagina. The cervix produces a special mucus that changes according to the woman’s menstrual cycle — the monthly process of releasing eggs in preparation for possible pregnancy (see “The ‘Men’ Words: Menstruation and Menopause,” later in this chapter).

During the first half of the cycle, especially around the time the woman releases the egg ( ovulates ), her mucus is abundant, clear, and watery. It is quite receptive to sperm penetration and survival, and sperm may live in the mucus for several days.

After ovulation occurs, the cervical mucus changes dramatically. It becomes thick, cloudy, and sticky, just about impenetrable to sperm trying to pass through the os, or opening of the cervix.

Making the cervical mucus impenetrable to sperm is one of the ways that the birth control pill prevents pregnancy. In addition, those practicing natural family planning can test the quality of the mucus as an indicator of fertility (see Chapter 7for more information on this technique).

The uterus is about the size of a pear, approximately 3 inches long. A muscular organ, the uterus collapses when empty. Its inner cavity is lined by a tissue called the endometrium , which develops and sheds regularly as part of the menstrual cycle. Menstruation occurs in response to ovarian hormones. The uterus is where the baby develops, and one look at a very pregnant woman tells you that the uterus has the ability to stretch incredibly. Luckily for us women, the uterus also goes back to its regular size after the baby has gone out into the big, wide world — or we’d be big and wide forever.

Leading into the ovaries are the fallopian tubes , each about 4 inches long (see Figure 3-4). The entrance to these tubes, near the ovary, is fairly large and lined with tiny “fingers,” called fimbria , which help to guide the eggs released by the ovary into one of the tubes.

Illustration by Kathryn Born

FIGURE 3-4:The ovaries and fallopian tubes: Where it all starts.

A woman has two ovaries , each about 1⁄2 to 1 inch long. The woman’s eggs are stored within the ovaries and then released, usually one at a time each month, at a signal given by the pituitary gland. A woman is born with 200,000 eggs, but by the time she reaches puberty, that number has dwindled to 400 or so.

The ovaries also release the female sex hormones, estrogen and progesterone. These hormones trigger the processes needed to create a baby.

I describe baby-making processes in Chapter 1. If you skipped that chapter, or maybe even if you didn’t, I suggest you go back and read it now. At its biological core, sex is about making babies, and that’s something you can never know too much about.

As far as the role that estrogen and progesterone play in a woman’s sexual desire, the evidence seems to tilt away from their having much of a role. Women also produce the male sex hormone, testosterone, and this may play somewhat of a role, but the evidence is not conclusive.

I don’t know why the two biggest female “problems” start with the prefix “men” — probably a Freudian slip on somebody’s part somewhere along the line.

Some women would disagree with my putting the word “problem” in quotes because they really do think of menstruation and menopause as problems. Because I’m basically an optimist, I refuse to categorize them as such.

Having your period may be inconvenient at times, and some of the aspects of menopause can be annoying, but both processes also have saving graces. I always believe that looking at the glass as half full is better than looking at it as half empty.

Females, from about the age of 12 to 50, release an egg every 28 days (or thereabouts because not every woman’s cycle is regular). If the egg meets a sperm that was among the 50 million or so placed there by a man during intercourse, a pregnancy begins. This process is called fertilization . A fertilized egg needs an inviting home where it can divide and subdivide until it becomes a baby. The designated nesting area is called the uterus . (Sometimes a fertilized egg winds up someplace else, which can cause serious complications.)

Although the egg doesn’t need much in terms of decorations on the walls, it does need a blood supply. So at the time of the month when a fertilized egg may mosey on by and attach itself, the uterus dolls itself up with plenty of blood in its lining that an egg would find quite dandy. But if no fertilized egg comes along and implants itself in the walls of the uterus, the uterus doesn’t need all that blood, and it sheds it through menstruation.