Studies suggest that learning more about how the vagina works can increase sexual pleasure for both men and women -- so consider this article homework!

iStockphoto/Thinkstock

The Vagina and Sexual Intercourse

When it comes to men and sex, they're pretty easy to figure out. Men's penises become erect when they're sexually aroused, and they release ejaculate when they've had an orgasm. Because women's arousal is harder to detect, and because women's orgasms aren't essential to reproduction, many people -- both men and women -- assumed that sex was something women put up with to have babies, not something that could be enjoyed.

Now, of course, there are plenty of resources, from Cosmopolitan magazine to sex therapists, who are ready to explain how a woman can gain pleasure from sex. For one thing, female arousal is now better understood. When a woman becomes sexually aroused, the labia minora become swollen and puffy, which causes salt water to push through the vaginal walls and provide lubrication. In addition, the Bartholin's glands at the vagina's entrance produce lubrication, but in both cases, that moisture is only provided for a few minutes, so additional lubrication may be needed to maintain comfort during sex.

When a woman is aroused, the clitoral hood retracts and the clitoris hardens and expands (much like an aroused penis). The clitoris is the only organ in the human body devoted solely to sensory pleasure, and it boasts 8,000 nerve endings packed into a very small space [source: Corinna]. For some women, direct contact with the clitoris can be sensory overload, and even painful, so while the clitoris is often described as a "magic button" of sorts, the button doesn't work the same way in every woman.

If you were paying attention during our vaginal anatomy section, however, you'll remember that the clitoris isn't strictly a part of the vagina, but rather located nearby. That's why you'll often hear talk of "clitoral orgasms" versus "vaginal orgasms." Some women can only experience the latter, some only the former and some women have both. A vaginal orgasm usually means that the clitoris is left out of the equation, which it often is in most sexual positions; most sex therapists advise oral or manual stimulation to effectively stimulate the clitoris.

Still, even when the external clitoris isn't being stimulated during vaginal intercourse, the internal clitoral tissue might be getting a good dose of friction. In fact, one of the reasons we spent so much time talking about the anatomy around the vagina in the first part of this article is that those areas play as much a part in sexual pleasure as the vagina does. When a penis or sex toy is inside the vagina, there can be pressure on the internal clitoris, the urethral sponge and the perineum, all of which can contribute to a woman's sexual pleasure. Pressure from another person's body, depending on the sexual position, can also add to that pleasure, and while none of these spots has as many nerve endings as the clitoris, they aren't too shabby in that count either, which means there's plenty of opportunity for a woman to experience pleasure from vaginal intercourse alone.

Many people think that the goal of vaginal intercourse is to stimulate the G-spot -- an area of tissue that has been credited with toe-curling orgasms. However, not every researcher is willing to believe it's there, no matter how many women claim otherwise. What gives? We'll investigate on the next page.