Human reproduction
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2008-06-27T19:09:54Z
Persian Poet Gal
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Reverted edits by [[Special:Contributions/HARRYCROSSISSOCOOL|HARRYCROSSISSOCOOL]] ([[User talk:HARRYCROSSISSOCOOL|talk]]) to last version by Prom3th3an
'''Human reproduction''' is the [[reproduction]] of [[humans]]. It is a form of [[sexual reproduction]], by [[sexual intercourse]] between human [[male]]s and [[female]]s. In the sexual intercourse, interaction between the [[Male reproductive system (human)|male reproductive system]] and the [[Female reproductive system (human)|female reproductive system]] results in [[pregnancy]], which is followed by [[childbirth]]
==Anatomy==
{{See|Human reproductive system}}
===The human male===
{{seedetails|Male reproductive system (human)}}
The male reproductive system contains two main divisions: the [[penis]], and the [[testicle|testes]], the latter of which is where sperm are produced. In humans, both of these organs are outside the [[abdominal cavity]]. Having the testes outside the abdomen best facilitates [[Thermoregulation|temperature regulation]] of the sperm, which require specific temperatures to survive.
Sperm are the smaller than the female ovum, and live approximately 2 weeks after production, requiring males to produce them continuously from the time of [[sexual maturity]] until death. Prior to ejaculation the produced sperm are stored in the seminal vesicle, a small gland that is located just behind the bladder.<br />A sperm cell is motile and swims via [[chemotaxis]], using its flagellum to propel itself towards the ovum.
===The human female===
{{seedetails|Female reproductive system (human)}}
The female reproductive system likewise contains two main divisions: the [[vagina]] and [[uterus]], which act as the receptacle for the sperm, and the [[Ovary|ovaries]], which produce the female's [[Ovum|ova]]. The vagina is attached to the uterus through the [[cervix]], while the uterus is attached to the ovaries via the [[Fallopian tube]]s. At certain intervals, the ovaries release an ovum, which passes through the fallopian tube into the uterus.
If, in this transit, it meets with [[Spermatozoon|sperm]], the sperm penetrate and merge with the egg, [[fertilisation|fertilizing]] it. The fertilization usually occurs in the oviducts, but can happen in the uterus itself. The zygote then [[implantation|implants]] itself in the wall of the uterus, where it begins the processes of [[embryogenesis]] and [[morphogenesis]]. When developed enough to survive outside the womb, the cervix dilates and contractions of the uterus propel the fetus through the birth canal, which is the vagina.
The ova, which are the female sex cells, are much larger than the sperm and are normally formed with in the ovaries of the fetus before its birth. They are mostly fixed in location with in the ovary until their transit to the uterus, and contain nutrients for the later [[zygote]] and [[embryo]]. Over a regular interval, in response to hormonal signals, a process of [[oogenesis]] matures one ovum which is released and sent down the Fallopian tube. If not fertilized, this egg is flushed out of the system through [[menstrual cycle|menstruation]].
==Process==
Human reproduction is a long process, starting with sexual intercourse, followed by nine months of pregnancy before childbirth. Many years of parental care is required in order to finish with a mature human being.
===Sexual intercourse===
{{Main|Human sexual intercourse}}
[[Human reproduction]] takes place as [[internal fertilization]] by [[sexual intercourse]]. During this process, the [[erect]] [[penis]] of the [[male]] is inserted into the [[female|female's]] [[vagina]] until the male [[ejaculate]]s [[semen]], which contains [[sperm]], into the female's vagina. The sperm then travels through the vagina and cervix into the [[uterus]] or [[fallopian tube]]s for fertilization of the [[ovum]]. Upon successful [[human fertilization|fertilization]] and implantation, [[gestation]] of the [[foetus]] then occurs within the female's uterus, called pregnancy.
===Pregnancy===
{{main|Pregnancy}}
Pregnancy is the period of time during which the fetus develops, dividing via [[mitosis]] inside the female. During this time, the fetus receives all of its [[nutrition]] and oxygenated blood from the female, filtered through the [[placenta]], which is attached to the fetus' [[abdomen]] via an [[umbilical cord]]. This drain of [[nutrient]]s can be quite taxing on the female, who is required to ingest slightly higher levels of [[calorie]]s. In addition, certain [[vitamin]]s and other nutrients are required in greater quantities than normal, often creating abnormal eating habits. Gestation is 40 weeks in humans.
===Birth===
{{main|Childbirth}}
Once the fetus is sufficiently developed, chemical signals start the process of birth, which begins with contractions of the uterus and the dilation of the cervix. The fetus then descends to the cervix, where it is pushed out into the vagina, and eventually out of the female. The newborn, which is called an [[infant]] in humans, should typically begin [[Respiration (physiology)|respiration]] on its own shortly after birth. Not long after, the placenta is passed as well. The end of the umbilical cord attached to the young’s abdomen eventually falls off on its own.
===Parental care===
{{Main|Parental care}}
Human's babies and children are nearly helpless and require high levels of [[parental care]] for many years. One important type of parental care is the use of the [[mammary gland]]s in the female [[breast]]s to [[lactation|nurse]] the baby.<ref>[http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Sexual_Reproduction.html Sexual Reproduction in Humans.] 2006. John W. Kimball. Kimball's Biology Pages, and online textbook.</ref>
==Political and social==
There are groups promoting more human reproduction and, on the other hand, those who think it is better more limited. [[Natalism]] is promoting reproduction, while, on the other hand, anti-natalism promotes [[birth control]], e.g. as a solution to [[overpopulation]] and its effects.
==References==
{{reflist}}
[[Category:Reproduction]]