The penis is a male body part found on the outside of the body. It is used for urination and for sexual reproduction. The main sexual function of the penis is to be inserted into a female's vagina and deliver semen which may cause pregnancy. This activity is called sexual intercourse.
Structure[change | change source]
The end of the corpus spongiosum forms the glans penis which is underneath the foreskin in uncircumcised males. The area on the bottom of the penis, where the foreskin is attached on uncircumcised men, is known as the frenulum.
The urethra, the tube where urine and semen travel through, runs down the corpus spongiosum (spongy tissue), and opens at the tip of the penis. Sperm are made in the testes (ball-like organs) and stored in the epididymis (layer of tissue) around the testes. During ejaculation, sperm are pushed up the vas deferens. Fluids are added by the seminal vesicles, the prostate gland and the bulbourethral glands to make semen.
Erection[change | change source]
A penis can become erect if a male is sexually aroused (or sometimes during sleep, even though there is no sexual stimulation). In an erection, the penis fills with blood. The blood makes the penis become longer, thicker and harder. Veins taking blood away from the penis get smaller, so less blood is taken through. Arteries bringing blood to the penis get wider, bringing more blood to the penis.
Ejaculation[change | change source]
In reproductive sexual intercourse between a male and female, the erect penis is inserted into the vagina and moved in and out. The vagina places pressure on the penis, which can cause the male to have an orgasm and ejaculate into the vagina, causing insemination.
Other forms of sex, like anal and oral sex, can also cause stimulation, and therefore orgasm and ejaculation. In masturbation, a male can stimulate the penis and other sensitive areas of the body, such as the scrotum, by rubbing the genital area. Ejaculation may also happen during sleep (called a 'wet dream'). A male must have started puberty before he can ejaculate. During orgasm, muscles push semen from the penis. Semen moves through the urethra and comes out of the hole at the tip of the penis.
Penis size in humans[change | change source]
The length and thickness of the penis is different for different people. The size of a soft penis (not erect) is much smaller than when it is erect. Some penises grow more when they get hard than other penises. In most cases, whether a penis is big or small, it can still be used for sex. It averages out to be around 3 to 6 inches long when not erect. The average size of an erect human penis is between 13 – 16 cm (5.1– 6 in). The average circumference of a penis is 12.3 cm (4.85 in) when fully erect. The penis grows bigger during puberty. At the start of puberty, the average length of the penis is 6 centimetres (2.4 in). The penis reaches adult size about 5 years later. A study done in 1996 found the mean length of an adult man's penis is 89 millimetres (3.5 in) when it is not erect. The average length of an erect penis is about 12.9 to 15 centimetres (5.1 to 5.9 in).
Circumcision[change | change source]
The foreskin is a fold of skin that covers the end of the penis. Cutting off the foreskin is called circumcision. The foreskin is connected to the head of the penis. During circumcision, the foreskin is removed from the penis. Circumcision is usually performed on infant males for medical, religious or cultural reasons.
Some males have the foreskin cut off when they are adults because they have problems with their foreskin. Some males have the foreskin cut off because they want to change how their penis looks.
In some religions, babies and young boys have their foreskin cut off. This is expected in Islam and Judaism. It is not required according to Christianity, but it is allowed and is common among Christians. In Judaism, infant males are required to have their foreskin removed as a sign of the covenant made with God.
Related pages[change | change source]
References[change | change source]
- Wessels, H (1996). "Penile length in the flaccid and erect states: guidelines for penile augmentation". http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=8709382&dopt=Abstract. Retrieved 2007-06-05.
- Chen, J (2000-12-1). "Predicting penile size during erection". http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11416836&query_hl=2&itool=pubmed_docsum. Retrieved 2006.
- "ANSELL RESEARCH - The Penis Size Survey". March 2001. http://www.free-condom-stuff.com/education/research.htm. Retrieved 2006-07-13.
- W.A. Schonfeld (1943). "Primary and Secondary Sexual Characteristics: Study of their Development in Males from Birth through Maturity, with Biometric Study of Penis and Testes". American Journal of Diseases of Children 65: 535.
- See also J. Chen; A. Gefen; A. Greenstein; H. Matzkin; D. Elad (2000). "Predicting Penile Size during Erection". International Journal of Impotence Research 12 (6): 328–333. doi:10.1038/sj.ijir.3900627. "Ansell Research: The penis size survey". Ansell Healthcare. March 2001. http://www.free-condom-stuff.com/education/research.htm. Retrieved 29 November 2008.
- "Circumcision". American-Israeli Cooperative Enterprise. 2006. http://www.jewishvirtuallibrary.org/jsource/Judaism/circumcision.html. Retrieved August 3.
- Beidelman, T. (1987). "CIRCUMCISION". The Encyclopedia of religion Volume 3. Ed. Mircea Eliade. New York: Macmillan Publishers. 511–514. Retrieved on 3 August 2016.
Other websites[change | change source]
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