Sex

Sex is a physical act of intimate touching or penetration that can result in biological reproduction and/or feelings of intimacy. While "sex" can refer to intercourse between a man and a woman, it can also describe other acts, including anal sex, oral sex, and can refer to homosexual encounters, as well as heterosexual encounters.

Sex is the way by which all mammals reproduce. During sexual reproduction the female egg (ovum) is fertilized by the male sperm to produce and embryo, which then develops in the female's uterus. Contraceptive devices may be employed by people who wish to have sex but not reproduce.

Though sex has many positive associations, including reproduction, pleasure, and intimacy, there are many negative aspects of sex. Unprotected sex can lead to the spreading of diseases, and can cause unintentional pregnancies. Sex has also been a high point of controversy throughout history. Many religions consider sex outside of marriage or sex with a person of the same gender (homosexuality) taboo, and standards continue to evolve regarding at what a age a person should first become sexually active. The portrayal of sex on television and in movies in the U.S. is highly restricted, for fear of enticing young people to become sexually active. In the same vein, a large-scale debate continues in the U.S. over whether or not children should participate in sex education courses at school, and at what age they should be taught about sex.

These are the typical stages that female animals will experience during the act of sexual intercourse:

1. Desire: The physical attraction to copulate with a partner, often fueled by pheromones--chemicals that attract the attention of members of the opposite sex.

2. Excitement: When women are excited their blood races to their genitals causing their heart rate and blood pressure to increase. This can mean one of two things, physical stimulation which can mean kissing and caressing or psychological stimulation which uses their minds by reminding them of fantasy's or erotic thoughts.

3. Plateau: This is a stage the woman will enter if stimulation is continued. During this phase her breathing will change, her muscles will tighten and she can turn flush red.

4. Orgasm: When a woman reaches her orgasm the muscles in her uterus, vagina and lower abdomen goes through powerful contractions.

5. Multiple orgasms Some women can experience multiple orgasms, where orgasm will be achieved multiple times during the same sex act, sometimes one right after another if a woman does not experience refractory periods where the body resets for another climax.

6. Resolution: After the woman experiences her orgasm, her body will return to normal. Her breathing and color will return to her normal state.

These are the typical stages that male animals will experience during the act of sexual intercourse:

1. Desire: The physical attraction to copulate with a partner, often fueled by pheromones--chemicals that attract the attention of members of the opposite sex.

2. Excitement: This is the beginning phase of arousal and usually manifests in men as increased blood pressure, heart rate, and breathing rate, and heightened muscle tension. Blood flow will increase to the genital area, resulting in an erection of the penis and sometimes the release of pre-ejaculatory fluids.

3. Plateau: This is the peak phase of sexual excitement which in men can include further increase in blood pressure, heart rate, and breathing rate. The penis and testes will usually continue to increase in size, and will release some pre-ejaculatory fluids which help in sperm survival inside the female system.

4. Orgasm: As a man orgasms he reaches the height of the "plateau" phase during the course of a minute or less. While the orgasm is occurring, blood pressure, heart rate, and breathing will be at their highest, the pelvic muscles will contract, and semen will be ejaculated. The male will feel muscle tension and contractions throughout the body. Then shortly after orgasm, the penis will decrease in size greatly.

5. Resolution: During this post-orgasm phase, the penis will return to its normal flaccid state, and the body will resume its normal rhythms and functions. Men will often feel extremely relaxed or even sleepy.http://www.micronutra.com/journal/shrinkage-dysfunction/the-male-sexual-response-cycle

The content in this page is not a substitute for professional medical advice. Please contact your doctor for more information about sex.

Sexual reproduction is the creation of offspring from two parents, who contribute their genetic material to the offspring.

Sexual reproduction occurs when two gametes fuse together and create a zygote. The male gamete is called the spermatozoa (known commonly in humans as "sperm"). The female gamete is called the ovum (also commonly known as the "egg"). This fusion of the gametes can take place either inside the female reproductive system, or outside of the body in some cases.

To achieve Sexual Reproduction, animals will seek out a partner of the opposite sex and have sexual intercourse to achieve fertilization of the female egg by the spermatozoa. Some water-dwelling animals will fertilize externally in the water.http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Sexual_Reproduction.html

Sexually Transmitted Diseases, or STDs, are diseases that are passed from one partner to another during acts of sex--including oral sex, or any form of intimate touching. There are 25 different types of known STDs, all of which vary greatly in symptoms and treatment options.http://www.avert.org/stds.htm There are some STDs that can be transmitted even if they are yet undetected by the carrier, and can be passed even when the carrier is showing no symptoms.

Partners can protect themselves from some STDs by always using a condom during sex. However, condoms cannot always provide 100% certain protection, and some STDs can be transmitted even with proper condom usage.

Here is a list of some of the most common STDs:

Chlamydia - is a bacterial STD that is caused by the Chlamydia trachomatis bacterium, and can affect the urethra, anus, cervix (women), throat, lungs, liver, and eyes. Many men and women who contract Chlamydia will remain asymptomatic, but may show symptoms such as painful urination, abnormal genital discharge (in both men and women), and women may experience painful intercourse or irregular menstrual cycles. Treatment is a course of antibiotics. Condoms can greatly reduce the chance of passing Chlamydia onto a partner.http://www.avert.org/chlamydia.htm

Herpes - is a virus that can be passed from genital-to-genital contact, or even from mouth-to-genital contact during oral sex (Herpes virus located on the mouth is more commonly known as cold sores, but can still spread as the HSV-1 form of Herpes to a person's genitals). Many people who carry the Herpes virus, either on their mouths or genitals, are asymptomatic and unaware they even have the virus, making it one of the most common STDs. It is estimated 1 in 5 adults is infected with the HSV-2 form of the Herpes virus. Symptoms include painful blisters appearing on the genitals (or mouth), flu-like symptoms, backache, and/or headache. Although there is no cure for Herpes, doctors can offer anti-viral treatments to reduce outbreak length, which can range normally from 3 days to 4 weeks (the latter being usually only the case in first outbreaks). While condoms may be able to help protect a sexual partner during sexual intercourse, it any sores outside of the condom area may still spread the virus. Additionally, people who are not showing any symptoms of Herpes can still pass it on to a partner, including mouth-to-genital spreading of the virus. Herpes can lead to complications during pregnancy, and pregnant women who suspect they may have Herpes should notify their doctors.http://www.avert.org/herpes.htm

Genital Warts - are caused by some types of the Human Papilloma Virus (HPV) and can produce warts in the genital area that look like flesh-colored bumps that can be smooth or or cauliflower-like in texture. The warts may appear singularly or in groups. HPV can be passed through most forms of sexual activity, including non-penetrative sexual activity, or can be passed from mother to baby during childbirth. There is no cure for genital warts. Condoms may offer some protection against genital warts if they completely cover all warts.http://www.avert.org/genital-warts.htm

Gonorrhea - aka "The Clap", is a very common STD caused by the Neisseria gonorrheoae bacterium. Symptoms include discharge from the vagina, penis, or anus, and a burning sensation while urinating. Because Gonorrhea can live in a person's throat, it can be transmitted by not only vaginal and anal sex, but also by oral sex (moving either from throat to genitals, or genitals to throat). Condoms can be quite effective against spreading Gonorrhea, when used correctly. Treatment for Gonorrhea involves a full round of antibiotics. If it is left untreated though, Gonorrhea can lead to severe medical complications.http://www.avert.org/gonorrhea.htm

HIV - or "Human Immunodeficiency Virus", is a viral infection that attacks the human immune system and leads to AIDS, a medical condition in which the body can no longer fight off infections, and leads to death. HIV can be passed on through sexual contact of all kinds, blood contact, or from mother to child. Consistent and proper condom use can protect sexual partners, so long as no sexual fluids or blood enter the partner's body. There currently is no cure for HIV or AIDS.http://www.avert.org/hiv.htm

Hepatitis A, B, and C - are all viral infections that typically affect the liver. Type A is generally passed on through anal or fecal contact with an infected person. Type B is generally passed through any type of penetrative sex, including oral sex, or by any form of sexual activity that may draw blood from an infected person. Type C is less common to contract through sex, although if there is any blood sharing during sex the virus may be passed, or if an infected woman is menstruating, she may pass type C that way. Symptoms include flu-like feelings, weight loss, jaundice, lack of appetite, and other symptoms. Treatments for Hepatitis vary greatly, and anyone who suspects they may be infected should contact a doctor.http://www.avert.org/hepatitis.htm

Syphilis - is a bacterial infection that can cause a wide variety of symptoms that begin as painless ulcers, and turn into rashes, flu-like feelings, hair loss, and more. Syphilis that remains untreated for years may cause irreversible damage to the nervous system. It is passed during vaginal sex, anal sex, and oral sex between unprotected partners. Condoms can offer some protection, but may not fully protect partners.http://www.avert.org/syphilis.htm