Sexual intercourse is the natural and most common way to make a baby. It involves a man and woman having sex without birth control until the man ejaculates, or releases, semen from his penis into the woman's vagina. The semen, which has sperm in it (which is made in his testicles), moves to the Fallopian tubes, and if it finds an ovum on its way, it will try to fertilize it. If this works, the now fertilized ovum sticks to the side of the uterus and the woman becomes pregnant. The fertilized ovum then develops into a human. Medically, it is called a pregnancy until birth.
Certain species of animals also have sex for other purposes than to bear offspring. These include Humans, bonobos, chimpanzees and dolphins. These species also are among those known to engage in homosexual behaviors.
In both humans and bonobos, the female has a relatively concealed ovulation. Neither male or female partners commonly know whether she is fertile at any given moment. One reason for this may be that sex partners of these species form strong emotional bonds. The partners come together for more than just sexual intercourse. In the case of humans, long-term partnership is more important than immediate sexual reproduction.
Humans, bonobos and dolphins show cooperative behaviour. In many cases, this behaviour has shown better results than what an individual can achieve alone. In these animals, the use of sex has evolved beyond reproduction and has taken additional social functions. Sex reinforces intimate social bonds between individuals. Overall, such cooperation also benefits each member of the group in that they are better able to survive.
In humans, sexual intercourse seems to serve three types of purposes,which do not exclude one another:
In the late 20th century, very effective forms of contraception (birth control) were developed allowing a man and women to help prevent a baby from being made when they have sex. One type of contraception is a condom. This is a piece of rubber that covers the penis that a man can wear during intercourse, which stops the man's semen from going into the woman's vagina. This does not always work though because the condom may rip or tear. Another well-known type of contraception is called the Pill, which a woman takes every day. When a woman is "on the Pill," she and her partner may have sex any time they wish with very little chance of making a baby. It is recommended that a couple who have a sexual relationship use two forms of contraception. That way if one fails the other is a 'backup'.
Contraception allows people to keep "sex for fun" separate from "sex to make children". For example, a fertile couple may use contraception to experience sexual pleasure (recreational). At the same time, this experience may strengthen their relationship, and a stronger relationship may mean that they will better be able to raise children in the future.
Who people like to have sex with depends on their sexuality. Men who like to have sex with women, and women who like to have sex with men are heterosexual or "straight". Men who only like to have sex with other men, and women who only like to have sex with other women are homosexual or "gay". A different word to describe a woman who only likes to have sex with other women is "lesbian". Some people like both men and women, which is called being bisexual. Others do not feel sexual attraction at all, and are referred to as asexual.
Approximately 1.5% of the UK's population in 2010 was bisexual or gay.
Some diseases can be caught by having sex. These diseases are called sexually-transmitted infections (STIs).
Some examples of STIs include chlamydia infection, syphilis and gonorrhoea. A virus called HIV causes AIDS, which cannot be cured and can lead to death.
Using Latex condoms or oral dams reduce the chance that a few types of diseases will be passed on, but it not entirely effective for all STIs. Birth control (like "the Pill") can prevent pregnancy, but won't prevent sexual infections.
Some STIs can also be spread in ways other than having sex. For example, herpes simplex and hepatitis B could be caught by a virgin without having sex, but can also be caught through sex. Some types of STIs can spread from contact between the genitals, mouth, anus, skin, eyes, and (rarely) infected surfaces; this depends a lot on the type of STI and how it spreads. Some common diseases like HPV can cause warts and cancer in the genitals or anus or throat.
There exists an HPV vaccine that prevents some sexually-transmitted strains of HPV; however, the vaccine only works if you get vaccinated before becoming infected. The vaccine is approved of for both men and women, but is often not required in the U.S. due to politics.
There are many other kinds of sex. Two of them are oral sex and anal sex.
Oral sex is when one partner uses the tongue, mouth, or throat to excite the other partner's sex organs.
Slangs for oral sex is common in Western cultures, for example: "going down on", "giving a blowjob", "giving head", or "eating out". The technical term for oral sex is fellatio if performed on a male and cunnilingus if performed on a female. When a man performs fellatio on himself, it is called autofellatio, and autocunnilingus if a woman performs cunnilingus on herself. Few men and women are able to do this.
People can get sexually transmitted infections from oral sex, such as herpes (which can be passed between the mouth and groin), HIV and even oral cancer.
Anal sex is when an erect penis or other device made for sexual pleasure is inserted into the sexual partner's anus. Anal sex with a female does not lead to pregnancy by itself, however, semen can leak out of the anus and enter into the vagina, and pregnancy may rarely occur. Anal sex can still pass sexually transmitted diseases from one partner to another. It can also be very unhealthy for the body because the skin around the anus can tear, bleed and get infected with bacteria. For safety and pleasure partners often use condoms, female condoms and/or lubrication.
A painful sexual act is a condition of repeated or persistent genital pain before, during, or after sexual intercourse due to physical, psychogenic and emotional causes. Doctors call the condition as "dyspareunia". It occurs in women and men. The condition affects up to one-fifth of women at some point in their lives.
Gerontology
Gerontology (from Greek: γέρων, "geron", "old man" and -λογία, "-logy", "study of") is the study of the social, psychological and biological aspects of aging. It is distinguished from "geriatrics", which is the branch of medicine that studies the disease of the elderly.
Gerontology includes these and other endeavors:
"Biogerontology" is the subfield of gerontology dedicated to studying the biological processes of aging. It includes "Biomedical gerontology," also known as "experimental gerontology" and "life extension", is a sub discipline of biogerontology that endeavors to slow, prevent, and even reverse aging in both humans and animals. Curing age-related diseases is one approach, and slowing down the underlying processes of aging with the help of physical exercises is another. Most "life extensionists" believe the human life span can be altered within the 21st century.
"Social gerontology" is a multi-disciplinary sub-field that specializes in studying or working with older adults. Social gerontologists may have degrees or training in social work, nursing, psychology, sociology, demography, gerontology, or other social science disciplines. Social gerontologists are responsible for educating, researching, and advancing the broader causes of older people by giving informative presentations, publishing books and articles that pertain to the aging population, producing relevant films and television programs, and producing new graduates of these various disciplines in college and university settings.
George Lowe