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Pre-ejaculate

Pre-ejaculate

Pre-ejaculate (also known as pre-ejaculatory fluid or Cowper's fluid) is the clear lubricating fluid that is issued from a man's penis when he is aroused. Slang terms for pre-ejaculate include pre-come, pre-cum, dog water, speed drop and widower's tears. The fluid is usually secreted by Cowper's glands during foreplay or at an early stage during sex, some time before the man reaches orgasm and semen is ejaculated. Pre-ejaculatory fluid prepares the urethra for the passage of semen and neutralizes acidity due to any residual urine. It also lubricates the movement of the foreskin over the glans. The amount of fluid that the human male can issue varies widely between individuals, from imperceptible amounts to a copious flow. A problem for couples who seek to avoid pregnancy, however, is that the pre-ejaculate may contain sperm. This is one additional reason why withdrawal (coitus interruptus) is not considered to be a reliable method of birth control. There have been no large-scale studies of sperm in pre-ejaculate, but some smaller-scale studies suggest that any sperm present may be ineffectual at causing pregnancy.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12286905] It is commonly held, but as yet unverified, that pre-ejaculate may pick up existing sperm in the urethra if the man has not urinated since his last ejaculation. An article in the April 2003 edition of the Journal of Assisted Reproduction & Genetics set out to determine "if spermatozoa are present in the preejaculatory penile secretion, originating from Cowper's gland." After seeing that none of the pre-ejaculate contained sperm, they concluded that "Preejaculatory fluid secreted at the tip of the urethra from Cowper's gland during sexual stimulation did not contain sperm and therefore cannot be responsible for pregnancies during coitus interruptus" [http://www.ingentaconnect.com/content/klu/jarg/2003/00000020/00000004/00461193] A more serious problem is those same studies have shown the presence of HIV, the virus responsible for the disease AIDS, in pre-ejaculate. Although the frequency of HIV transmission through oral-genital contact is fairly low [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11364482] a risk still exists. Pre-ejaculate can also transmit other STDs. Category:Andrology

Penis

The penis (plural penises) is in addition to the scrotum one of the external male sexual organs. Other terms for it are: the (male) member or - for the erect state - the phallus. The penis is the male reproductive organ and for mammals additionally serves as the external male organ of urination. The penis is homologous to the female clitoris and in the theory of evolution, it originated from the same embryonic structure.

Linguistics

Etymology

The word is derived from the Latin word for tail, also used to describe the organ, "penis". The Latin word "phallus" (from the Greek "phallos") is sometimes used to describe the penis, though the word originally was used to describe images, pictoral or carved, of the penis [http://www.etymonline.com/index.php?search=penis&searchmode=none]. Some derive the Latin word penis from earlier
- pesnis, and the Greek word peos = "penis" from earlier
- pesos.

Synonyms

For a far more exhaustive and multi-lingual thesaurus, see the entry on [http://en.wiktionary.org/wiki/WikiSaurus:penis WikiSaurus].

The human penis

The human penis differs from those of some other mammals. It has no baculum, or erectile bone; instead it relies entirely on engorgement with blood to reach its erect state. It cannot be withdrawn into the groin, and is larger than average in proportion to body mass.

Structure

baculum The human penis is made up of three columns of erectile tissue:
- the two corpora cavernosa (singular: corpus cavernosum) and
- one corpus spongiosum The corpus spongiosum lies on the underside (known also as the ventral side) of the penis; the two corpora cavernosa lie next to each other on the upper side (dorsal side). The end of the corpus spongiosum is enlarged and cone-shaped and forms the glans penis. The glans supports the foreskin or prepuce, a loose fold of skin that in adults can retract to expose the glans. The area on the underside of the penis, where the foreskin is attached, is called the frenum (or frenulum). The urethra, which is the last part of the urinary tract, traverses the corpus spongiosum and its opening, known as the meatus, lies on the tip of the glans penis. It is both a passage for urine and for the ejaculation of semen. Sperm is produced in the testes and stored in the attached epididymis. During ejaculation, sperm are propelled up the vas deferens, two ducts that pass over and behind the bladder. Fluids are added by the seminal vesicles and the vas deferens turns into the ejaculatory ducts which join the urethra inside the prostate gland. The prostate as well as the bulbourethral glands add further secretions, and the semen is expelled through the penis. The raphe is the visible ridge between the lateral halves of the penis, found on the ventral or under side of the penis, running from the meatus (opening of the urethra) across the scrotum to the perineum (area between scrotum and anus).

Relation to female genitals

The glans of the penis is homologous to the clitoral glans, the corpora cavernosa are homologous to the body of the clitoris, the corpus spongiosum is homologous to the vestibular bulbs beneath the labia minora, and the scrotum is homologous to the labia minora, labia majora and clitoral hood. The raphe does not exist in females, because there the two halves are not connected.

Erection

Main article: Erection Erection Erection is the stiffening and rising of the penis which occurs in the sexually aroused male, though it can also happen in non-sexual situations. The primary physiological mechanism that brings about erection is the autonomic dilation of arteries supplying blood to the penis, which allows more blood to fill the three spongy erectile tissue chambers in the penis, causing it to lengthen and stiffen. The now engorged erectile tissue presses against and constricts the veins that carry blood away from the penis. More blood enters the penis than leaves until an equilibrium is reached (equal volume of blood flowing into the dilated arteries and out of the constricted veins). A constant erectile size is achieved at equilibrium. Inability to attain a satisfactory erection is known medically as erectile dysfunction, or ED in short. A drug against this condition, sildenafil citrate (marketed as Viagra®) works by vasodilation. Erection facilitates sexual intercourse though it is not essential for some other sexual activities. Although many erect penises point upwards (see illustration), it is common and normal for the erect penis to point nearly vertically upwards or nearly vertically downwards, depending on the tension of the suspensory ligament that holds it in position. Stiffness of erectile angle also varies.

Size

See main article Human penis size As a general rule, an animal's penis is proportional to its body size, but this varies greatly between species — even between closely related species. For example, an adult gorilla's erect penis is about 1.5 inches (4 cm) in length; an adult chimpanzee, significantly smaller (in body size) than a gorilla, has a penis size about double that of the gorilla. The common chimpanzee, or pan troglodytes, has the third largest penis size among the great apes: in comparison, the human penis is somewhat larger than the common chimpanzee, both proportional to body size and in absolute terms; one study has found that the average human penis is 5 inches (12.7 cm) in length when fully engorged with blood during arousal. As with any other bodily attribute, the length and girth of the penis is highly variable between individuals of the same species. In many animals, especially mammals, the size of a flaccid penis is much smaller than its size when erect. In humans and some other species, flaccid vs. erect penis size varies greatly between individuals, such that penis size when flaccid is not a reliable predictor of size when erect. Except for extreme cases at either end of the size spectrum, penis size does not correspond strongly to reproductive ability in almost any species.

Normal variations

Depending on temperature, a flaccid (not erect) penis of average size can withdraw almost completely within the body. During erection the penis will return to its normal (erect) size. Other variations:
- Pearly penile papules are raised bumps of somewhat paler colour around the base of the glans and are normal. See sidebar picture and picture at article.
- Fordyce's spots are small, raised, yellowish-white spots 1-2mm in diameter that may appear on the penis, as well as the inner surface and vermilion border of the lips of the face, and are normal.
- Sebaceous prominences are raised bumps similar to Fordyce's spots on the shaft of the penis, located at the sebaceous glands and are normal.
- Phimosis, an inability to retract the foreskin fully, is harmless in infants and pre-pubescent males, occurring in about 8 percent of boys at age 10.

Disorders affecting the penis

Oedema (swelling) of the foreskin can result from sexual activity, including masturbation. It appears worrying but so long as the foreskin is in its normal position and blood flow is present it's harmless. See paraphimosis for situations where the foreskin can't be moved to its normal position or the swelling persists. If the condition recurrs regularly, medical advice should be obtained, since it can be a symptom of conditions such as chronic heart disease. ([http://www.links.net/vita/corp/catdick/ description of a case resulting from sexual activity, with pictures]) Pathological Phimosis--where a non-retracting foreskin is accompanied by pain or physiological distress, or affects physical hygiene, requires treatment which can be surgical or non-surgical depending on the seriousness of the condition. See Phimosis for more details. Paraphimosis is an inability to move the foreskin forward over the glans. It can result from fluid trapped in a foreskin which is left retracted, perhaps following a medical procedure, or accumulation of fluid in the foreskin because of friction during vigorous sexual activity. Applying pressure to compress the glans, then moving the foreskin to its normal position is the initial procedure to follow, perhaps with the assistance of a lubricant. Placing the penis in normal granulated sugar can reduce the swelling via osmosis. If the condition persists for more than several hours or there is a sign of lack of blood flow, a hard glans with no erection or an inability to urinate, it should be treated as a medical emergency. In Peyronie's disease, anomalous scar tissue grows in the soft tissue of the penis, causing curvature. Severe cases can benefit from surgical correction. A thrombosis can occur during periods of frequent and prolonged sexual activity, especially fellatio. It is usually harmless and self-corrects within a few weeks. Pudendal nerve entrapment is a condition characterized by pain on sitting and loss of penile (or clitoral) sensation and orgasm. Occasionally there is a total loss of sensation and orgasm. The pudendal nerve can be damaged by narrow hard cycle seats and accidents. Penile fracture can occur if the erect penis is bent excessively. A pop or cracking sound and pain is normally associated with this event. Emergency medical assistance should be obtained. Prompt medical attention lowers likelihood of permanent penile curvature.[http://www.blackwell-synergy.com/links/doi/10.1046/j.1464-410X.1996.86420.x/abs/] In diabetes, peripheral neuropathy can cause tingling in the penile skin and possibly reduced or completely absent sensation. The reduced sensations can lead to injuries for either partner and their absence can make it impossible to have sexual pleasure through stimulation of the penis. Since the problems are caused by permanent nerve damage, preventive treatment through good control of the diabetes is the primary treatment. Some limited recovery may be possible through improved diabetes control. Erectile dysfunction, formerly known as impotence, is the inability to have and maintain an erection sufficiently firm for satisfactory sexual performance. A wide variety of generally effective treatments are available. Diabetes is a leading cause, as is normal aging. Priapism is a painful and potentially harmful medical condition in which the erect penis does not return to its flaccid state. The causative mechanisms are poorly understood but involve complex neurological and vascular factors. Potential complications include ischaemia, thrombosis, and impotence. In serious cases the condition may result in gangrene, which may necessitate amputation.

Developmental disorders of the penis

Hypospadias is a developmental disorder where the meatus is positioned wrongly at birth. Hypospadias can also occur iatrogenically by the downward pressure of an indwelling urethral catheter.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=9554017] It is usually corrected by surgery. A micropenis is a very small penis caused by developmental or congenital problems.

Penis replacement

The first successful penis allotransplant surgery was done on September 2005 in a military hospital in Guangzhou, China. (Guangzhou Daily, [http://www.southcn.com/news/gdnews/nanyuetuijian/200509220074.htm source]) A man at 44 sustained an injury after an accident and his penis was severed. Urination became difficult as his urethra was partly blocked. A newly brain-dead man, at 23, was tracked down and his penis selected for the transplant. Despite atrophy of blood vessels and nerves after a protracted period of time had elapsed (exact length not given), the arteries, veins, nerves and the corpora spongiosa were successfully matched. After seven hours' surgery, the penis regained its function and even managed to attain erection. The difficulty in this surgery is attributable to these demands: The shape of the donor's penis must sufficiently match that of the receiver's and the duration between detaching and attaching the penis must be short. It remains to be observed if infection or rejection has occurred after the transplant and how much sexual function the man would regain. Urination ability, however, is predicted to resume after a week.

Alleged and observed penis-related psychological disorders

- penis panic (koro in Malaysian/Indonesian) - delusion of shrinkage of the penis and retraction into the body.
- penis envy - the contested Freudian belief of a woman envying men for having a penis.

Altering the male genitalia

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Uncircumcised penis (L), circumcised penis (R).

Main article: genital modification and mutilation The most prevalent form of genital alteration in some countries is circumcision: removal of part or all of the foreskin for various cultural, religious, and more rarely medical reasons. In many cases, such as in some United States hospitals, the frenulum and part of the shaft skin is also removed. Circumcision likely arose in the Middle East desert to avoid the effects of desert sand getting under the foreskin; the practice has been incorporated into organised religions which originated in desert areas such as Islam and Judaism. Secular reasons for circumcision, however, have been disputed. Less commonly, the penis is sometimes pierced or decorated by other body art. Such alterations are almost universally elective and usually for the purpose of aesthetics or increased sensitivity. Piercings of the penis include the Prince Albert piercing, the apadravya piercing, the ampallang piercing, the dydoe piercing, and the frenum piercing. Foreskin restoration or stretching is a further form of body modification. Other practices which alter the penis are also performed, although they are rare in Western societies without a diagnosed medical condition. Apart from a penectomy, perhaps the most radical of these is subincision, in which the urethra is split along the underside of the penis. Subincision originated among Australian Aborigines, although it is now done by some in the U.S. and Europe.

Fears and reassurance

Possibly due to shame inculcated in regard to genitalia, some people suffer from misunderstandings and resultant fear. Penis panic is a kind of hysteria that appears to be culturally conditioned and largely limited to Sudan, China, Japan, and Southeast Asia. As mentioned earlier, the raphe is the visible ridge between the lateral halves of the penis, found on the ventral or under side of the penis, running from the meatus (opening of the urethra) across the scrotum to the perineum (area between scrotum and anus). This ridge is actually the "biological zipper" that closes the urethra during the normal course of fetal development. When the urethra does not close normally, the resulting condition is called hypospadias. Surgery is required to close the urethra. Treatment may involve multiple surgeries and attendant pain. Other beliefs involve the idea that masturbation can cause insanity or blindness. In childhood, according to the study Paediatric penile trauma, male circumcision is the most common form of genital trauma; it occurred in two-thirds of the physical traumas examined. (El-Bahnasawy 2002) [http://www.ingentaconnect.com/content/bsc/bju/2002/00000090/00000001/art02741]

Non-human penises

masturbation Most marsupials, except for the two largest species of kangaroos, have a bifurcated penis. That is, it separates into two columns, and so the penis has two ends. The barnacle has the longest penis for its own length: up to twenty times the length of the animal. Urban legend alleges that the dolphin has prehensile control over his penis. In the realm of absolute size, the smallest penis belongs to the common shrew (5 mm or 0.2 inches). The largest penis belongs to the blue whale estimated at over 2 m (about 6 feet). Accurate measurements are difficult to take because the whale's erect length can only be observed during mating. The Icelandic Phallological Museum is devoted entirely to collecting penis specimens from all the land and sea mammals living in Iceland. The museum has received a legally-certified gift token for a future specimen belonging to Homo sapiens. In male insects, the structure homologous to a penis is known as aedeagus. Male specimes of the Squamata order of reptiles have two paired organs called hemipenes. Gorillas have relatively small penises, so it is an often used subtle insult in countries such as Australia to insinuate or directly state that one is 'hung like a gorilla'.

Cultural aspects involving penises

Uses of animal penises

- Culinary, e.g., in Chinese gastronomy
- Magical and therapeutic, in medicine and/or superstition, especially as an aphrodisiac or even cure against impotence
- Also used for dog toys, such as the bull pizzle

Uses of human penises in cultural traditions

- Esthetical, e.g., Body modification
- For the symbolic and artistic use, see under phallus
- In humor, e.g., in scatology - considered indecent or completely taboo in various cultures

External links

- [http://www.phallus.is/ The Icelandic Phallological Museum], collection of over one hundred and fifty penises and penile parts belonging to almost all the land and sea mammals that can be found in Iceland
- [http://www.neo-tech.com/penis/ Penis Size Chart] (actual-size chart suitable for printing out and comparing)
- [http://www.afraidtoask.com/members/index.html AfraidToAsk.com's Male Genitalia Guide]
- [http://www.my-penis.org/ All About the Penis]
- [http://www.the-penis-website.com/ The Penis Website]
- [http://www.penisowner.com/pom/pom.html Shagnasty's Penis Owners Manual]
- [http://www.the-penis.com A Website About the Penis and Male Sexuality]
- [http://www.edu.uni-klu.ac.at/~amiklaut/dr_nick/answer19.htm Summary Penis Size data]
- [http://www.the-penis.com/mythsandfacts.html Details Penis Size Data]
- [http://www.indiana.edu/~kinsey/resources/bib-penis.html Kinsey Institute on the penis]
- [http://www.askmen.com/sports/health/health4.html Ask Men about penis]
- [http://www.circumstitions.com/Glossary.html A Glossary of the Penis] Note: This is an anti-circumcision website.
- [http://www.cirp.org/pages/anat/ Anatomy of the Penis - Mechanics of Intercourse] Note: This is an anti-circumcision website.
- [http://www.circumstitions.com/Restric/Gallery1.html A gallery of uncircumcised penises] Category:andrology Category:reproductive system Category:Sexual anatomy ja:陰茎 ko:남자의 성기 ms:Zakar simple:Penis

Cowper's gland

In the anatomy of the male human body, the bulbourethral glands (or Cowper's glands) are two small, rounded, and somewhat lobulated bodies, of a yellow color, about the size of peas, placed behind and lateral to the membranous portion of the urethra, between the two layers of the fascia of the urogenital diaphragm. They lie close above the bulb, and are enclosed by the transverse fibers of the Sphincter urethrae membranaceae. Their existence is said to be constant: they gradually diminish in size as age advances. The excretory duct of each gland, nearly 2.5 cm long, passes obliquely forward beneath the mucous membrane, and opens by a minute orifice on the floor of the cavernous portion of the urethra about 2.5 cm in front of the urogenital diaphragm. They secrete a clear fluid known as pre-ejaculate or Cowper's fluid (colloquially known as "pre-cum") which is generated upon sexual arousal. Cowper's glands in males are homologous to Bartholin's glands in females.

Structure

Each gland is made up of several lobules, held together by a fibrous investment. Each lobule consists of a number of acini, lined by columnar epithelial cells, opening into one duct, which joins with the ducts of other lobules outside the gland to form the single excretory duct. :Note: The first version of this article was taken from the public domain text of the 1918 edition of Gray's Anatomy, and so may not reflect modern anatomical knowledge -- please update as necessary Category:Andrology Category:Exocrine system Category:Reproductive system ja:尿道球腺

Foreplay

In human sexual behavior, foreplay is physical intimacy usually at the beginning of a sexual encounter that serves to build up sexual arousal, sometimes in preparation for sexual intercourse or another act meant to bring about sexual enjoyment and orgasm. Examples of foreplay in hetereosexual sex may include the touching and kissing of a woman's breasts and genitalia (by the male) and/or the stimulation of the man's penis by the female. Male homosexual sex foreplay often includes the kissing of the other man's nipples and neck, as well as oral sexual exploration. Foreplay varies between cultures. Some acts which may be considered foreplay may include kissing (especially French kissing), petting and stroking, touching of the genitals and mutual masturbation, oral sex, and sexual roleplaying, fetish activities, or BDSM.

Orgasm

An orgasm, also known as a sexual climax, is a pleasurable physical, psychological or emotional response to prolonged sexual stimulation. It is often accompanied by a notable physiological reaction, such as ejaculation, blushing or spasm and may be followed by aftershocks. Dictionaries still give the subsidiary meaning, "a similar point of intensity of emotional excitement," but as of 2005 this usage has become obscure. It can be startling to modern readers when encountered in older literature.

General

Both males and females can experience orgasm, but the exact response varies across gender. Generally speaking, orgasm is the third stage of four in the human sexual response cycle, which is the currently accepted model of the physiological process of sexual stimulation.

Shared physiology

Orgasm is the conclusion of the plateau phase of the sexual response cycle, shared by males and females alike. During orgasm, both males and females experience quick cycles of muscle contraction in the lower pelvic muscles, which surround both the anus and the primary sexual organs. Orgasms in both men and women are often associated with other involuntary actions, including vocalizations and muscular spasms in other areas of the body. Also, a generally euphoric sensation is associated with orgasm. Afterwards, orgasm generally causes perceived tiredness, and both males and females often feel a need to rest. This is often attributed to the release of endorphins during orgasm causing relaxation and drowsiness, but can also be due to the body's need for a short rest after a bout of vigorous physical activity. A recent [http://www.timesonline.co.uk/article/0,,589-1662280,00.html study] at the University of Groningen has indicated significant differences in brain activity during the female and male orgasm. PET scans showed that both the female and male orgasm 'shut down' areas in the brain associated with anxiety and fear (the Amygdala). It was found that the male orgasm focused the brain on sensory input from the genitals more than was the case for the female orgasm.

Human male orgasm

In a human male orgasm, there are rapid, rhythmic contractions of the prostate, urethra and the muscles at the base of the penis, which (in the adult) typically force stored semen to be expelled through the penis's urethral opening. This is referred to as ejaculation. The process usually takes from 3 to 10 seconds. The process is usually, but not always, extremely pleasurable. Orgasm is generally induced by direct stimulation of the penis. Some men experience heightened orgasm by direct stimulation of the prostate through the perineum. Following ejaculation, a refractory period usually occurs during which a man cannot have another orgasm. This period can be anywhere from less than a minute to over half a day, depending on age and other individual factors. A very few cases have been reported of men who appear to have no refractory period at all. Scientists theorize that a pituitary gland disorder or difference may cause this unique ability.

Male prostate orgasm

Some men are able to achieve ejaculation or orgasm through intra-anal stimulation of the prostate gland. Men reporting the sensation of prostate stimulation often give descriptions similar to women's accounts of g-spot stimulation. Other men report finding anal stimulation or penetration of any kind to be painful, or simply that they find no profound pleasure from it. With sufficient stimulation, the prostate can also be "milked". Providing that there is no simultaneous stimulation of the penis, prostate milking can cause ejaculation without orgasm. When combined with penile stimulation, some men report that prostate stimulation increases the volume of their ejaculation, and provides an enhanced and more pleasurable version of the standard male orgasm.

Male multiple orgasms

It is possible to have an orgasm without ejaculation, dry orgasm, or to ejaculate without reaching orgasm. Some men report that the ability to consciously separate orgasm and ejaculation has allowed them to achieve multiple orgasms. Men who have practiced this technique extensively report that they can sometimes experience a continuous "wave" of orgasm. This can last, in theory, indefinitely, but in practice is limited by the man's ability to concentrate/meditate and "surf" the "wave". In recent years a number of sex manuals for men have delved into this technique. Men who have become adept at this practice also report more powerful ejaculatory orgasms when they choose to have them. It is uncertain whether this is a result of more time between ejaculations, or a direct result of practice. Interestingly, the male multiple orgasm requires that the man "hold on", maintaining control to prevent ejaculation. In contrast, multi-orgasmic women sometimes report that they must relax and "let go" to experience multiple orgasms. Internet rumors and a few scientific studies have pointed to the hormone prolactin as the likely cause of the male refractory period. Because of this, there is currently an experimental interest in drugs which inhibit prolactin, such as Dostinex (also known as Cabeser, or Cabergoline). Anecdotal reports on Dostinex suggest it may be capable of eliminating the refractory period altogether, allowing men to experience multiple ejaculatory orgasms in rapid succession. No scientific study explicitly supports these claims, but a German study cites unspecific increase in sexual pleasure. Dostinex is a hormone altering drug and has many potential side effects. It has not been approved for treating sexual dysfunction. To date, the only known scientific study to successfully document natural, fully ejaculatory, multiple orgasms in an adult male was conducted at Rutgers University in 1995. During the study, six fully ejaculatory orgasms were experienced in 36 minutes with no refractory period in evidence. The study was subsequently published in the "Journal of Sex Education and Therapy" (1998; Volume 23, No. 2; pp 157-162).

Human female orgasm

In a human female orgasm, orgasm is preceded by moistening of the vaginal walls, and an enlargement of the clitoris due to increased blood flow trapped in the clitoris's spongy tissue. Some women exhibit a sex flush; a reddening of the skin over much of the body due to increased blood flow to the skin. As a woman comes closer to having orgasm, the clitoris moves inward under the clitoral hood, and the labia minora (minor lips) becomes darker. As orgasm becomes imminent, the vagina decreases in size by about 30% and also becomes congested with blood. The uterus then experiences muscular contractions. A woman experiences full orgasm when her uterus, vagina and pelvic muscles undergo a series of rhythmic contractions. The majority of women consider these contractions to be very pleasurable. After the orgasm is over, the clitoris re-emerges from under the clitoral hood, and returns to its normal size in less than 10 minutes. Unlike men, women either do not have a refractory period or have a very short one, and thus can experience a second orgasm soon after the first; some women can even follow this with a third, or even fourth orgasm; this is known as having multiple orgasms. After the initial orgasm, subsequent climaxes may be stronger or more pleasurable as the stimulation accumulates. Research shows that about 13% of women experience multiple orgasms; a larger number may be able to experience this with the proper stimulation (such as a vibrator) and frame of mind. However, some women's clitorises are too sensitive after orgasm, making additional stimulation painful; they are probably not able to experience multiple orgasms.

The evolutionary purpose of orgasms

Some evolutionary biologists believe that female orgasms have a distinct purpose, such as increasing intimacy with a male partner in order to ensure the survival of the pair bond. Others have theorized that they increase fertility by enhancing sperm retention. The British biologists Baker and Bellis have suggested that the female orgasm may have an "upsuck" action, retaining favourable sperm and making conception more likely. Other biologists, such as Stephen Jay Gould, suggest the female orgasm is analogous to the male nipple, an evolutionary holdover which, though associated with pleasure in the context of sexual behaviour, has no specific identified biological function.

Orgasm as vestigial

The clitoris is homologous to the penis, that is, the penis and clitoris develop from the same embryonic structure. It has been claimed by some researchers, such as Stephen Jay Gould that the clitoris is vestigial in the female, and that female orgasm serves no particular evolutionary function. Proponents of this theory, such as Dr. Elisabeth Lloyd, point to the relative difficulty of achieving female orgasm through vaginal sex, and limited evidence for increased fertility after orgasm. Feminists such as Natalie Angier have criticized that this theory understates the psychosocial value of female orgasm.

Genetic basis of individual variation

33% of women report never or seldom achieving orgasm during intercourse, and only 10% always orgasm. This variation in ability to orgasm is generally thought to be psycho-social, but has been found to be between 34-45% genetic, according to a 2005 twin study published in Biology Letters, a Royal Society journal.[http://news.bbc.co.uk/1/hi/health/4616899.stm][http://www.eurekalert.org/pub_releases/2005-06/rs-sir060605.php] The researchers stated that the fact that it is heritable suggests that evolution has a role. They suggested this difficulty in achieving orgasm might have evolved because it helped females select males who were the most powerful and thoughtful, who would be the most likely to hang around as a long-term partner and be a better bet for bringing up offspring. In this theory, women who orgasm easily may have been satisfied with mates who were less skilled. While in certain cultures it has been posited that women who are more orgasmic may be more promiscuous, there has to date been no confirmation of this in a scientific study.

Vaginal versus clitoral orgasms

A distinction is sometimes made between clitoral and vaginal orgasms in women. An orgasm that results from combined clitoral and vaginal stimulation is called a blended orgasm. Many doctors and feminist advocates have claimed that vaginal orgasms do not exist, and that female orgasms are obtained only from clitoral arousal. Recent discoveries about the size of the clitoris — it extends inside the body, around the vagina — would seem to support this theory. On the other hand, other sources argue that vaginal orgasms are dominant or more "mature". This latter viewpoint was first promulgated by Sigmund Freud. In 1905, Freud argued that clitoral orgasm was an adolescent phenomenon, and upon reaching puberty the proper response of mature women changes to vaginal orgasms. [http://www.uno.edu/~asoble/pages/koedt.htm] While Freud did not provide evidence supporting this basic assumption, the consequences of the theory were greatly elaborated thereafter. In 1966, Masters and Johnson published pivotal research into the phases of sexual stimulation. Their work included women as well as men, and unlike Kinsey previously (in 1948 and 1953), set out to determine the physiological stages leading up to and following orgasm. [http://health.discovery.com/centers/sex/sexpedia/mandj.html] One of the results was the promotion of the idea that vaginal and clitoral orgasms follow the same stages of physical response. Additionally, Masters and Johnson argued that clitoral stimulation is the primary source of orgasms. This standpoint has been adopted by feminist advocates, to the extent that some hold that the vaginal orgasm was a mirage, created by men for their convenience. Certainly many women can only experience orgasm with clitoral stimulation, either alone or in addition to vaginal stimulation, while (less commonly) other women can only experience orgasm with vaginal stimulation. The clitoral-only orgasm school of thought became an article of faith in some feminist circles. Alternatively, some feminists feel the clitoral orgasm robs females of the source of their womanhood. A new understanding of vaginal orgasm has been emerging since the 1980s. Many women report that some form of vaginal stimulation is essential to subjectively experience a complete orgasm, in addition to or instead of external (clitoral) stimulation. Recent anatomical research has pointed towards a connection between intravaginal tissues and the clitoris. It has been shown that these tissues have connecting nerves. This, combined with the anatomical evidence that the internal part of the clitoris is a much larger organ than previously thought could also explain credible reports of orgasms in women who have undergone clitoridectomy as part of so-called female circumcision. In some cases it is possible for women to orgasm through stimulation of secondary sexual organs (e.g. breasts), and in very rare cases, without any direct stimulation to the genitalia or the other specific erogenous zones, but instead stimulation of the non-specific zones (e.g. neck). Some women experience orgasm while giving birth.

Controversy: definition of orgasm

There is controversy surrounding male multiple orgasms, and female G-spot (vaginal, not blended) orgasms, because some feel that they do not fit within the clinical definition of orgasm. Male multiple orgasms, while pleasurable, often do not involve involuntary contractions. Similarly, there are not always contractions in female orgasms resulting from stimulation of the g-spot alone, without stimulation of the clitoris. However, both of these sensations in both sexes are extremely pleasurable, and are often felt throughout the body, creating a mental state that is often described as transcendental. Because of this, some sexologists feel that these experiences can be accurately defined as orgasms. Others insist that that orgasm is defined strictly by muscular contractions, and that these other sensations are too subjective to be quantified as orgasms.

Orgasm in post-operative transsexuals

Transwomen

Post-operative male-to-female transsexual women (having undergone vaginoplasty) generally experience full orgasm, involving any combination of the clitoris, vagina and labia. Some transwomen experience female ejaculation, which can be from the prostate gland, seminal vesicles, and/or Cowper's glands, which are not removed during vaginoplasty.

Transmen

Post-operative female-to-male transsexual men (after having undergone metoidioplasty or phalloplasty) generally experience orgasm in the same way as other men, except that those who have had phalloplasty have a pump installed to create an erection, as the neopenis (with either surgical technique) has limited natural erection capability. Due to the lack of the necessary glands, they do not have the ability to ejaculate.

Orgasmic dysfunction

The inability to have orgasm is called anorgasmia, or inorgasmia. In situations where orgasm is desired, anorgasmia is mainly thought of as being caused by an inability to relax, or 'let go'. It seems to be closely associated with performance pressure and an unwillingness to pursue pleasure, as separate from the other person's satisfaction. It was the psychoanalyst Wilhelm Reich, in his 1927 book The Function of the Orgasm, who first made orgasm central to the concept of mental health and defined neurosis in terms of blocks to having full orgasm. For a variety of reasons, some people choose to fake an orgasm.

Drugs and orgasm

Certain drugs have been reported to have enhancing effects on orgasm. Alkyl nitrites are used by some men to enhance orgasm. Marijuana has widely been reported to enhance and prolong male orgasms, while at the same time delaying ejaculation. Stimulant, Psychedelic, and Ecstasy drug users of both sexes report heightened sexual pleasure. Some male cocaine users report rubbing the glans of their penis with cocaine in order to numb it and delay ejaculation. The use of drugs to enhance orgasm has potentially hazardous side effects. Studies have indicated that each of the three major erectile dysfunction drugs have different reported effects on orgasm. Anecdotal evidence suggests that women have enhanced orgasms with Sildenafil. In men Sildenafil has varying effects on orgasm. Some men report enhancement, while others report that while they can achieve an erection with Sildenafil, their orgasms feel "hollow". Vardenafil behaves very similarly to Sildenafil. Tadalafil, a newer drug, in addition to treating erectile dysfunction over longer periods of time, is said to enhance orgasm and shorten the male refractory period. Some drugs, such as Cabergoline, are reported to shorten the refractory period without having any effect on erections or orgasms. While prescribing drugs to solve problems, many sex therapists discourage the regular use of drugs to enhance sex, because of the elevated risk of dependency. Inversely, a number of anti-depressant drugs, especially those in the class of selective serotonin reuptake inhibitors (SSRIs), have as a side effect in those who use them the inability to achieve orgasm. One potential basis of this side effect is penile anesthesia.

Orgasm in Tantric sex

In the Asian spiritual tradition of sexual practice known as Tantric sex, orgasm has a different value than in other cultural approaches to sexuality. Some practitioners of Tantric sex aim to eliminate orgasm from sexual intercourse by remaining for long periods of time at the pre-orgasmic state. According to some advocates of Tantric sex, such as Rajneesh, practicing Tantric sex without orgasm will eventually lead to orgasmic feelings spreading out to all of conscious experience. Some current advocates of Tantric sex claim that in Western culture sexuality is put in the service of orgasm in a way that reduces the ability to have intense pleasure during each moment of sexual experience, and consequently that eliminating the striving toward orgasm enhances the pleasure to be derived from all aspects of sexual experience.

Orgasm in non-humans

The mechanics of the male orgasm are similar in most mammals, and females of some mammalian species have clitorises. There is evidence that some non-human animals, particularly primates, can experience orgasm in ways similar to humans.

Non-sexual meaning of the word "orgasm"

Dictionaries still indicate that the word "orgasm" can refer to any peak of emotional intensity—a "climax" in the non-sexual sense. As of 2005, the word would be likely to be misunderstood if used in that way; such usage is vanishingly rare. It does, however, occur in literature written prior to the sexual revolution: :Here in this cathedral at Burgos was the record of an incredible spiritual energy.... Those who had built and carved and painted here had been more than happy. They had left the record of their ecstasy in a divine orgasm of stone.—Hervey Allen, Anthony Adverse In reference to a horse which is calming down after being "spooked:" :"it was a very weak and very sick mare he rode, stumbling and halting, afflicted with nervous jerks and recurring muscular spasms—the aftermath of the tremendous orgasm through which she had passed.—Jack London, Moon-Face and Other Stories, "Planchette." In the following sentence, a newcomer to the Arctic is impressed with Malemute Kid's forceful personality. ("Breathing heavily" here means "asleep.") :"Malemute Kid was already breathing heavily; but the young mining engineer gazed straight up through the thick darkness, waiting for the strange orgasm which stirred his blood to die away."—Jack London, The Son of the Wolf, "An Odyssey of the North".

External links

- Wallen, Kim, "[http://userwww.service.emory.edu/~kim/orgasm.html An Annotated Bibliography on Sexual Arousal, Orgasm, and Female Ejaculation in Humans and Animals]". Department of Psychology, Emory University. Atlanta, GA.
- [http://www.beautifulagony.com/ Beautiful Agony - the beauty of human orgasm]
- [http://www.master-your-g-spot.com/female_orgasm.html Pages on female orgasm and the g spot]

References

- Singer, J., and I. Singer. Types of Female Orgasm. In J. LoPiccolo and L. LoPiccolo, eds., Handbook of Sex Therapy. New York: Plenum Press, 1978.
- Dr KM Dunn, Dr LF Cherkas and Prof TD Spector "Genetic influences on variation in female orgasmic function: a twin study" Biology Letters, a Royal Society journal. June 2005.
- Whipple, B., Myers B., and Komisaruk, B. "Male Multiple Ejaculatory Orgasms: A Case Study", J Sex Ed & Therapy 1998 23(2):157-162.
- Reich, Wilhelm. The Function of the Orgasm. New York: Farrar, Strauss, and Giroux, 1986. ISBN 0374502048 ja:オーガズム

Urethra

In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes, to pass urine to the outside, and also a reproductive function in the male, as a passage for sperm. The external urethral sphincter is a smooth muscle that allows voluntary control over urination.

Anatomy

Men have a longer urethra than women. This means that women tend to be more susceptible to infections of the bladder (cystitis) and the urinary tract. The length of a male's urethra, and the fact it contains a number of bends makes catheterisation more difficult. In the human female, the urethra is about 1-1.5 inches (2.5-4 cm) long and opens in the vulva between the clitoris and the vaginal opening. In the human male, the urethra is about 8 inches (20 cm) long and opens at the end of the penis. The urethra is divided into three parts in men, named after the location:
- The prostatic urethra crosses through the prostate gland. There is a small opening where the vas deferens enters.
- The membranous urethra is a small (1 or 2 cm) portion passing through the external urethral sphincter. This is the narrowest part of the urethra.
- The spongy (or penile) urethra runs along the length of the penis on its ventral (underneath) surface. It is about 15-16 cm in length, and travels through the corpus spongiosum. corpus spongiosum

Histology

The epithelium of the urethra starts off as transitional cells as it exits the bladder. Further along the urethra there are stratified columnar cells, then stratified squamous cells near the external meatus (exit hole). There are small mucus-secreting urethral glands, that help protect the epithelium from the corrosive urine.

Medical problems of the urethra

- Hypospadias and epispadias are forms of abnormal development of the urethra in the male, where the opening is not quite where it should be (it occurs lower than normal with hypospadias, and higher with epispadias). A chordee is when the urethra develops between the penis and the scrotum.
- Infection of the urethra is urethritis, said to be more common in females than males. Urethritis is a common cause of dysuria (pain when urinating).
- Related to urethritis is so called urethral syndrome
- Passage of kidney stones through the urethra can be painful and subsequently it can lead to urethral strictures Endoscopy of the bladder via the urethra is called cystoscopy.

Foreskin

The foreskin or prepuce is a retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus when the penis is not erect. Almost all mammals including marsupials [http://www.uq.edu.au/news/?article=2193] and marine mammals [http://www.doc.govt.nz/Publications/004~Science-and-Research/DOC-Science-Internal-Series/PDF/DSIS104.pdf] have foreskins. Only monotremes [http://encarta.msn.com/encyclopedia_761553537_2/Reproductive_System.html] (the platypus and the echidna) lack foreskins. In females, the clitoral hood (see that article), is an analogous structure.

The human foreskin

Description

clitoral hood In humans, the outside of the foreskin is like the skin on the shaft of the penis but the inner foreskin is a mucous membrane like the inside of the eyelid or the mouth. Like the eyelid, the foreskin is free to move. Smooth muscle fibres keep it close to the glans but make it highly elastic.[http://www.cirp.org/library/anatomy/lakshmanan/] At the end of foreskin there is a band of tissue called the ridged band which is rich in nerve endings called Meissner's corpuscles [http://www.cirp.org/library/anatomy/cold-taylor/]. The foreskin is attached to the glans with a frenulum which helps retract the foreskin over the glans. In children, the foreskin covers the glans completely but in adults this need not be so. In a German study, [http://www.male-initiation.net/library/medicus/schoeberlein.html#start Schoeberlein] found that about 50% of young men had full coverage of the glans, 42% had partial coverage, and in the remaining 8%, the glans was uncovered. After adjusting for circumcision, he stated that in 4% of the young men the foreskin had spontaneously atrophied (shrunk).

Development

Eight weeks after fertilization, the foreskin begins to grow over the head of the penis, covering it completely by 16 weeks. At this stage the foreskin and glans share an epithilium (mucous layer) that fuses the two together. It remains this way until the foreskin separates from the glans [http://www.cirp.org/library/general/gairdner/]. At birth, the foreskin is usually still fused with the glans [http://www.cirp.org/library/anatomy/deibert/]. As childhood progresses the foreskin and the glans gradually separate, a process that may not be complete until the age of 17 [http://www.cirp.org/library/general/oster/]. A Danish survey reported that average age of first foreskin retraction in Denmark is 10.4 years.[http://www.cirp.org/library/normal/thorvaldsen1/] Wright argues that forcible retraction of the foreskin should be avoided and that the child himself should be the first one to retract his own foreskin [http://www.cirp.org/library/normal/wright2/]. Premature retraction may be painful, and may result in infection.

Functions

In koalas the foreskin contains naturally occurring bacteria that play an important role in fertilisation [http://www.uq.edu.au/news/?article=2193]. Some also believe that the foreskin has protective and erogenous functions in humans [http://www.chw.edu.au/parents/factsheets/circumj.htm], though this is disputed. Cold and Tayor stated "The prepuce is primary, erogenous tissue necessary for normal sexual function."[http://www.cirp.org/library/anatomy/cold-taylor/] Gairdner states that the foreskin protects the glans [http://www.cirp.org/library/general/gairdner/] but some studies show that inflammation of the glans is more common when the foreskin is present.[http://www.circs.org/library/waskett3/index.html] Also, Freud states that "[superficial ulceration of the urethral meatus] occurs chiefly in circumcised children but may be found in the noncircumcised as well if the prepuce leaves the tip of the glans free to irritation."[http://www.cirp.org/library/complications/freud1/] Morgan wrote that the foreskin's gliding action facilitates sexual intercourse [http://www.cirp.org/library/general/morgan2/]. Shen (China) found a statistically significant
- (p = 0.001) increase in erectile disfunction following circumcision. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14979200&query_hl=27]. Pang and Kim (South Korea) reported "Of those who were circumcised long after they had been sexually active, > 80% reported no noticeable difference in sexuality, but a man was twice as likely to have experienced diminished sexuality than improved sexuality." [http://www.blackwell-synergy.com/doi/abstract/10.1046/j.1464-410X.2002.02545.x?cookieSet=1] Fink's study of American men also found significantly worsened erectile function
- (p = 0.01)[http://www.cirp.org/library/sex_function/fink1/]. Other studies came to different conclusions. Collins (USA), Senkul (Turkey), and Masood (Britain) found no significant difference in erectile function [http://www.circs.org/library/collins/] [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16037710&query_hl=13] [http://www.circs.org/library/senkul/]. Senkul found that the circumcised men took significantly longer to ejaculate after circumcision
- (P = 0.02) [http://www.circs.org/library/senkul/]. Laumann's study of American-born men found "little difference between circumcision status and sexual dysfunction for the two younger cohorts" (18-29 and 30-44). However, older men (45-59) with foreskins in his sample were significantly more likely to suffer from erectile dysfunction overall
- (p < 0.05) and trouble achieving and maintaining an erection
- (p. < 0.05). Premature ejaculation and performance anxiety were also noted
- (both p. < 0.10). Circumcision rates were also significantly different in different ethnic groups (less common in Blacks and Hispanics) and they varied with the education level of the mother (less common in those with less education). [http://www.cirp.org/library/general/laumann/] and [http://www.circs.org/library/laumann/]. Denniston states that the foreskin's innervation provides input to the central and autonomic nervous system to provide erectile function, stimulate ejaculation, and provide pleasure.[http://www.cirp.org/library/sex_function/denniston3/] Fink's study reported less sensitivity after circumcision, though this only bordered on statistical significance
- (p = 0.08). [http://www.cirp.org/library/sex_function/fink1/] In contrast, Masood et al. reported improved sensation in 38% of men following circumcision and less sensation in 18%. 61% expressed greater satisfaction following removal of the foreskin, less satisfaction in 17%, and no change in 22%. [http://www.cirp.org/library/sex_function/masood1/] Interpretation of these findings vary. For example, Masood said, "Penile sensitivity had variable outcomes after circumcision. The poor outcome of circumcision considered by overall satisfaction rates suggests that when we circumcise men, these outcome data should be discussed during the informed consent process." [http://www.cirp.org/library/sex_function/masood1/] Hill and Denniston listed Senkul's finding of an increased ejaculatory time as a "demonstrated adverse effect" of circumcision [http://jme.bmjjournals.com/cgi/eletters/30/3/237#411] However, Senkul stated: "Adult circumcision does not adversely affect sexual function. The increase in the ejaculatory latency time can be considered an advantage rather than a complication. ... However, concerning the cause of that increase, in a Muslim community, the psychological influence of circumcision may be more pronounced than the organic effect." Please see sexual effects of circumcision for more information.

Conditions

Frenulum breve is where the frenulum is insufficiently long to allow the foreskin to fully retract, which may lead to discomfort during intercourse. The frenulum may also tear during intercourse. Phimosis is a condition when the foreskin of an adult cannot be retracted properly. (Before adulthood, the foreskin may still be separating from the glans [http://www.cirp.org/library/normal/kayaba/].) Phimosis can be treated by gently stretching the foreskin, using topical steroid ointments, preputioplasty, or by circumcision. See phimosis for more information. A condition called paraphimosis may occur if a tight foreskin becomes trapped behind the glans and swells as a restrictive ring. This can cut off the blood supply ischaemia to the glans penis and is a medical emergency. Applying crushed ice to the affected area may help, but seek medical assistance immediately. Aposthia is a rare condition in which the foreskin is not present at birth.

Surgical and other modifications of the foreskin

Circumcision is the removal of the foreskin, either partially or completely. It may be done for religious, aesthetic, health, or hygiene reasons, or to treat disease. Preputioplasty is a procedure to relieve a tight foreskin without resorting to circumcision. Other practices include genital piercings involving the foreskin and slitting the foreskin [http://www.emedicine.com/med/topic2874.htm].

- Statistics

Several of the studies noted in this article refer to statistically significant findings. Statistical significance is a measure of confidence that an observed association is not due to chance. It is often expressed as a p value, where p stands for the probability that the finding is due to chance. Thus, a lower value of p means a stronger association. A finding is considered significant if p is less than a certain value, called the significance level. The choice of level is somewhat arbitrary,[http://www.itl.nist.gov/div898/handbook/eda/section3/eda35.htm] but commonly chosen values are 0.10, 0.05, and 0.01.[http://www.stat.yale.edu/Courses/1997-98/101/sigtest.htm] [http://www.itl.nist.gov/div898/handbook/eda/section3/eda35.htm] A p value of 0.10 means that the probability of the finding occurring by chance is 10% or 1 in 10. A p value of 0.08 is an 8% probability of a chance occurrence, or one in 12.5 A p value of 0.05 is a 5% probability, or 1 in 20. A p value of 0.02 is 2%, or 1 in 50 A p value of 0.01 is 1%, or 1 in 100. A p value of 0.001 is 0.1%, or 1 in 1000. A finding of statistical significance does not by itself demonstrate that one thing caused another. See also statistical significance [http://www.stat.tamu.edu/stat30x/notes/node42.html]

External links

- Lakshmanan S., Prakash S. [http://www.cirp.org/library/anatomy/lakshmanan/ Human prepuce: some aspects of structure and function]. Indian J Surg 1980;44:134-7.
- Davenport M. [http://bmj.bmjjournals.com/cgi/content/full/312/7026/299 Problems with the penis and prepuce]. British Medical Journal 1996;312:299-301.
- Simpson ET, Barraclough P. [http://www.cirp.org/library/hygiene/simpson1/ The management of the paediatric foreskin]. Aust Fam Physician 1998;27(5):381-3.
- Cold CJ, McGrath KA. [http://www.cirp.org/library/anatomy/cold-mcgrath Anatomy and histology of the penile and clitoral prepuce in primates]. Male and Female Circumcision 1999
- [http://circuncision.tripod.com/ Circuncisión en Español] Circumcision discussion (in Spanish and English)
- Video "The Prepuce" a film prepared by Doctors Opposing Circumcision for medical students. (WMP, streaming) http://www.doctorsopposingcircumcision.org/DOC/prepuce.html (WMP, download) http://www.doctorsopposingcircumcision.org/video/Circumcision_WM7NTSC_256k_D.wmv Category:pelvis Category:Andrology Category:Circumcision

Glans penis

The glans penis is the sensitive erectile tip of the penis. It is wholly or partially covered by the foreskin, except when the foreskin is retracted, such as during sexual intercourse while the penis is erect, or when the foreskin has been removed by circumcision.

Medical considerations

The meatus (opening) of the urethra is at the tip of the glans penis. In some infants and young boys who are still in nappies (diapers), the meatal area of the glans penis is at risk from meatitis, meatal ulceration, and possibly meatal stenosis.[http://www.cirp.org/library/complications/freud1/] The epithelium of the glans penis is mucocutaneous tissue.[http://www.cirp.org/library/anatomy/halata2/] Birley et al. report that excessive washing with soap may dry the mucous membrane that covers the glans penis and cause non-specific dermatitis.[http://www.cirp.org/library/disease/balanitis/birley/] Inflammation of the glans penis is known as balanitis. It occurs in 3-11% of males, and up to 35% of diabetic males. It has many causes, including irritation, or infection with a wide variety of pathogens. Careful identification of the cause with the aid of patient history, physical examination, swabs and cultures, and biopsy are essential in order to determine the proper treatment.[http://www.cirp.org/library/disease/balanitis/edwards1/]

Anatomical details

The glans penis is the expanded cap of the corpus spongiosum. It is moulded on the rounded ends of the corpora cavernosa penis, extending farther on their upper than on their lower surfaces. At the summit of the glans is the slit-like vertical external urethral orifice. The circumference of the base of the glans forms a rounded projecting border, the corona glandis, overhanging a deep retroglandular sulcus, behind which is the neck of the penis. The foreskin maintains the mucosa in a moist environment.[http://www.cirp.org/library/anatomy/prakash/] In males who have been circumcised, but have not undergone restoration, the glans is permanently exposed and dry. Contrary to widely-held belief, the glans of the circumcised penis does not develop a thicker keratinisation layer.[http://www.circs.org/library/szabo/] Studies have shown that the glans is equally sensitive in circumcised and uncircumcised males,[http://www.circs.org/library/masters/] [http://www.circs.org/library/bleustein] however, many males who have restored their foreskin disagree with these findings. The observed increase in sensitivity frequently is often attributed to the increase in moistness of the covered glans, although others have proposed the placebo effect.[http://www.circs.org/library/kirby/] [http://www.circs.org/library/waskett/] Halata & Munger (1986) report that the density of genital corpuscles is greatest in the corona glandis,[http://www.cirp.org/library/anatomy/halata/] while Yang & Bradley (1998) report that their study "showed no areas in the glans to be more densely innervated than others."[http://www.circs.org/library/yang/] Halata & Spathe (1997) reported that "the glans penis contains a predominance of free nerve endings, numerous genital end bulbs and rarely Pacinian and Ruffinian corpuscles. Merkel nerve endings and Meissner corpuscles are not present."[http://www.cirp.org/library/anatomy/halata2/] Yang & Bradley argue that "The distinct pattern of innervation of the glans emphasizes the role of the glans as a sensory structure".[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=9698671]

External links

- Freud P. [http://www.cirp.org/library/complications/freud1/ The ulcerated urethral meatus in male children]. J Pediatr 1947;31(4):131-41.
- Halata Z, Munger BL. [http://www.cirp.org/library/anatomy/halata/ The neuroanatomical basis for the protopathic sensibility of the human glans penis]. Brain Research 1986;371(2):205-30.
- Halata Z, Spaethe A. [http://www.cirp.org/library/anatomy/halata2/ Sensory innervation of the human penis]. Adv Exp Med Biol 1997;424:265-6.
- Yang CC, Bradley WE [http://www.circs.org/library/yang/ Neuroanatomy of the penile portion of the human dorsal nerve of the penis]. Br J Urol 1998;82(1):109-13. Category:reproductive system Category:andrology ja:陰茎#亀頭と包皮

Pregnancy

:For a broader view of pregnancy in mammals see mammalian pregnancy. For the medicine of pregnancy, see Obstetrics. Obstetrics Pregnancy is the carrying of one or more embryos or foeti by female mammals, including humans, inside their bodies. In a pregnancy there can be multiple gestations (for example, in the case of twins, or triplets). Human pregnancy is the most studied of all mammalian pregnancies. Human pregnancy lasts approximately 40 weeks between the time of the last menstrual cycle and birth (38 weeks from fertilisation). The medical term for a pregnant woman is "genetalian," just as the medical term for the unborn human is an embryo (early weeks) and then "foetus" (until birth). A woman who is pregnant for the first time is known as a primigravidanite or gravida 1: a woman who has never been pregnant is known as a gravida 0; similarly, the terms para 0 and para 1 are used for the number of times a woman has given birth. In many societies' medical and legal definitions, human pregnancy is arbitrarily divided into three trimester periods, as a means to simplify reference to the different stages of fetal development. The first trimester period carries the highest risk of miscarriage (natural death of embryo or fetus), while during the second trimester the development of the fetus can start to be monitored and diagnosed. The third trimester marks the beginning of viability, which means the fetus can survive if an early natural or induced birth occurs. Because of the possible viability of developed fetus, cultural and legal definitions of life often consider a fetus in the third trimester to be a distinct living person. :See also Pregnancy terms and definitions
Detection and dating
Pregnancy terms and definitions The beginning of pregnancy may be detected in a number of ways, including various pregnancy tests which detect hormones generated by the newly-formed placenta. Clinical blood and urine tests can detect pregnancy as early as 6-8 days after date of conception. Home pregnancy tests are personal urine tests, which normally can't detect a pregnancy until at least 12-15 days after conception. Both clinical and home tests can only detect the state of pregnancy, and cannot detect the actual date of conception. Home pregnancy test In practice, for the purpose of giving a date for a conception (i.e. an "age" for an embryo), doctors typically date the pregnancy by "menstrual date," based on the first day of a woman's last menstrual period, as the woman reports it. Unless a woman's recent sexual activity has been limited, the exact date of conception or implantation are unknown. And absent any symptoms of morning sickness, the only visible sign of a pregnancy is often an interruption of her normal monthly menstruation cycle, (i.e. a "late period"). Hence, the "menstrual date" is simply a common educated estimate for the age of a fetus, which is an average of two weeks later than conception, (the margin of error considers 0 to 30 days after last menstruation, hence a 14 day average). The term "conception date" may sometimes be used when that date is more certain, though even medical professionals can be imprecise with their use of the two distinct terms. An unknown date for conception means that in practice the distinction between embryo and fetus is a clinical one only, and not used as to refer to stages of development of a particular pregnancy. margin of error There are likewise finer distinctions between the concepts of fertilization (conception) and the actual state of pregnancy. In a normal pregnancy, the fertilization of the egg usually will have occurred in the Fallopian tubes or in the uterus. (In women with fertility problems, an egg may become fertilized yet fail to become implanted in the uterus.) If the pregnancy is the result of in-vitro fertilization the fertilization will have occurred in a Petri dish, after which "pregnancy" begins when one or more zygotes implants after being transferred by a physician in the woman's uterus. In the context of political debates regarding a proper definition of life, the terminology of pregnancy can be confusing. Because precise assessment of a pregnancy as being at the "embryo" or "fetus" stage is usually undeterminable, the terms (though more clinically precise) are less commonly used than terms like "baby" or "child." The medically and politically neutral term which remains is simply "pregnancy," though this can be problematic as it only refers indirectly to the embryo or fetus. In the context of personal treatment, bedside manner generally dictates that doctors make sparse use of clinical language like "fetus" and "embryo," and instead simply refer to the developing child as a "baby." progesterone
Timeline of a typical pregnancy
Pregnancy is typically broken into three periods, or trimesters, each of about three months. While there are no hard and fast rules, these distinctions are useful in describing the changes that take place over time.
First trimester

Fertilization
progesterone progesterone Before pregnancy begins, a female oocyte (egg) must be fertilized, by male sperm in a process referred to in medicine as "fertilization," or commonly as "conception." Pregnancy is usually dated as beginning on the first day of a woman's last menstrual period. This date is used to estimate an EDD, or Estimated Date of Delivery. Traditionally (according to Naegele's Rule, which is used to calculate the estimated date of delivery (EDD)), a human pregnancy is considered to last approximately 40 weeks (280 days) from the last menstrual period (LMP), or 37 weeks (259 days) from the date of conception. However, a pregnancy is considered to have reached term between 37 and 43 weeks. Babies born before the 37 week mark are considered premature, while babies born after the 43 week mark are considered postmature. postmature However, the average length of pregnancy depends on ethnic background of the mother (Caucasian women are more likely to have a longer pregnancy than other women) and if it is a first pregnancy (which tend to last longer than subsequent pregnancies). For example, a Caucasian woman's first pregnancy lasts an average 274 days from conception (288 days from the last menstrual period). An accurate date of conception is important, because it is used in calculating the results of various prenatal tests (for example, in the triple screen test). A decision may be made to induce labour if a baby is perceived to be overdue. Due dates are only a rough estimate, and the process of accurately dating a pregnancy is complicated by the fact that not all women have 28 day menstrual cycles, or ovulate on the 14th day following their last menstrual period. Approximately 3.6% of all mothers deliver on the due date predicted by LMP, and only 4.7% give birth on the day predicted by ultrasound.
Implantation
In medicine, pregnancy is defined as beginning when the developing embryo becomes implanted into the endometrial lining of a woman's uterus. The outer layers of the embryo grow and form a placenta, for the purpose of receiving essential nutrients through the uterus wall. The umbilical cord in a newborn child signifies the remnants of the connection to the placenta. The developing baby undergoes tremendous growth and changes during the process of embryonic and fetal development. Morning sickness aflicts about half of all pregnant women, typically only in the first trimester.
Second trimester
Morning sickness Most women feel more energised in this period, and begin to seriously put on weight. The first movement of the baby, often referred to as "quickening", can be felt, as the baby begins to form into a recognisable shape.
Third trimester
Final weight gain takes place, and the baby begins to move regularly. This can be uncomfortable, causing symptoms like weak bladder control and back-ache.
Medical aspects of pregnancy
Diagnostic criteria are: In a woman who has regular menstrual cycles and is sexually active, a period delayed by a few days or weeks is suggestive of pregnancy; elevated B-hcG to around 100,000 mIU/mL by 10 weeks of gestation.
Birth
Morning sickness Childbirth is the process in which the baby is born. It is considered by many to be the beginning of a person's life, where age is defined relative to this event in most cultures. A woman is considered to be in labour when she begins experiencing regular painful uterine contractions, accompanied by changes of her cervix — primarily effacement and dilation. While childbirth is widely experienced as painful, some women do report painless labours.
Postnatal Period
For topics following on from a successful pregnancy and birth, see:
- Breastfeeding
- Child development
Terms and definitions

Technical

- zygote - from fertilization until second cell division
- embryo - conceptus between time of fertilization to 10 weeks of gestation
- fetus - from 10 weeks of gestation to time of birth
- FASD - Fetal Alcohol Spectrum Disorder, a clinical term for the effects alcohol can have on the developing fetus
- gestational age - time from last menstrual period (LMP) up to present
- gravidity (G) - number of times a woman has been pregnant
- infant - time of birth to 1 year of age
- viability - minimum age for fetus survival, ca. third trimester
- previable infant - delivered prior to 24 weeks
- preterm infant - delivered between 24-37 weeks
- term infant - delivered between 37-42 weeks
- first trimester - up to 14 weeks of gestation
- second trimester - 14 to 28 weeks of gestation
- third trimester - 28 weeks to delivery
- parity (P) - number of pregnancies with a birth beyond 20 weeks GA or an infant weighing more than 500 g
- Ga Pw-x-y-z - a = number of pregnancies, w = number of term births, x = number of preterm births, y = number of miscarriages, z = number of living children; for example, G4P1-2-1-3 means the woman had a total of 4 pregnancies, of which 1 is of term, 2 are preterm, 1 miscarriage, and 3 total living children (1 term + 2 preterm).
Colloquial
There are a number of colloquialisms for pregnancy, usually regional. The action of impregnating a woman or girl is called 'knocking (her) up' in Canada and some parts of the U.S., and the state of being pregnant 'knocked-up'. The term 'lady-in-waiting', meaning a pregnant mother, is used broadly in the U.S. The word 'gone' or 'along' is used to represent gestational time, e.g. 'she's really far gone' or 'about 6 weeks gone' or 'six months along'. In the southern U.S. the euphemism of a water well is occasionally used to represent pregnancy (e.g. 'drink out of the well', to become pregnant), and a baby almost ready to be delivered is 'on his/her road'. Eastern Seaboard slang describes the mother as being 'in a fix' or, occasionally, 'preggers'; the Southern U.S. equivalent is 'in the family way'. An alternate term not slang or colloquial is 'with child', now restricted mainly to England. 'Having a bun in the oven' is another frequently used phrase to indicate that a woman is pregnant.
See also

- Abortion
- Lamaze
- Obstetrics
- Contraception
- Twin and Multiple birth
- Teenage pregnancy
- Pregnancy discrimination
- Low birth weight paradox
- Pregnancy in science fiction
- Melasma
- Wrongful abortion
- False pregnancy
- Simulated pregnancy
Reference

- Mittendorf R, Williams MA, Berkey CS, Cotter PF. The length of uncomplicated human gestation. Obstet Gynecol 1990;75:929-32. PMID 2342739.
External links

- [http://www.mayoclinic.com/health/pregnancy/HQ00451 Early pregnancy: Morning sickness, fatigue and other common symptoms, from MayoClinic.com]
- [http://www.visembryo.com/ The visible embryo]
- [http://www.merck.com/mrkshared/mmanual/section18/chapter249/249a.jsp Normal Pregnancy, Labor, And Delivery (Merck Manual)]
- Alan Guttmacher Institute [http://www.agi-usa.org/pubs/tgr/08/2/gr080207.html (2005) The Implications of Defining When a Woman Is Pregnant discussion of the political and legal background.
- [http://www.normalbirth.lamaze.org Lamaze Institute for Normal Birth], an advocacy site for "natural" childbirth.
- [http://www.chabad.org/library/article.asp?AID=72141 Jewish customs for conduct during Pregnancy and Birth] chabad.org Category:Midwifery Category:Obstetrics Category:Women Category:Fertility ko:임신 ja:妊娠

Coitus interruptus

Coitus interruptus, also commonly called pulling out, the withdrawal method, the Hail Mary method, the natural method, pull and pray, belly shot, raw dog and bail, or Vatican roulette is an unreliable method of contraception in which, during sexual intercourse, the man removes his penis from the woman's vagina just before he reaches orgasm. That way, the ejaculation of semen is not in the vagina but elsewhere. This method has been widely used for at least 2,000 years and was used by an estimated 38 million couples worldwide in 1991 (Population Action International). Used by itself, this method is unreliable, because of the difficulty of controlling the process of ejaculation. It has been suggested that the pre-ejaculate ("Cowper's fluid"), which has a lubricatory function, contains spermatozoa (sperm cells), and is easily drawn into the vagina by capillary action. However, modern research suggests that in fact there are no live sperm in the fluid, and the primary cause of failure of this method of contraception is the lack of self-control of those using it: interrupting just at climax can be psychologically difficult, as it goes entirely against instincts and reflexes all designed to encourage procreation by encouraging ejaculation to occur deeply within the vagina. It is also largely ineffective in the prevention of STDs, since pre-ejaculate may carry viral particles or bacteria which may infect the partner should the fluid come in contact with mucous membranes. However, a reduction in the volume of bodily fluids exchanged during intercourse may reduce the likelihood of disease transmission due to the smaller number of pathogens present. The advantage of coitus interruptus is that it can be used by people who have religious objections against or do not have access to other forms of contraception. It has no cost, requires no artificial devices, has no physical side effects, and can be practiced without a prescription or medical consultation. The disadvantage, as stated, is that it can be unreliable. The Bible may be describing this method in the story of Onan. According to a widely circulated joke, the obstetrics and gynaecology nurses' argot term for a woman relying on "the natural method" is "mother". In actuality, being educated about different forms of natural methods and combining them can improve the effect. According to Emory University, withdrawal has a typical failure rate of 19%. However, for the couples that use this method correctly, the failure rate is 4% [http://www.gynob.emory.edu/familyplanning/withdrawal.cfm]. In comparison the pill has a first-year failure rate of 5%, which drops to about 0.1% if used correctly [http://www.gynob.emory.edu/familyplanning/pills.cfm] while the diaphragm has a typical user failure rate of 20% and a perfect user failure rate of 6% [http://www.fda.gov/fdac/features/1997/conceptbl.html].

References

- Population Action International (1991). "A Guide to Methods of Birth Control." Briefing Paper No. 25, Washington, D. C.
- Rogow, Deborah, and Horowitz, Sonya. (1995). "Withdrawal: A Review of the Literature and an Agenda for Research." Studies in Family Planning. Vol 26, No 3 (May-June 1995), pp. 140-153.
- Weschler, Toni, "Taking Charge of Your Fertility: The Definitive Guide to Natural Birth Control and Pregnancy Achievement." ISBN 0060950536 Category:Birth control Category:Contraception

HIV

The human immunodeficiency virus, commonly called HIV, is a retrovirus that primarily infects vital components of the human immune system such as CD4+ T cells, macrophages and dendritic cells. It also directly and indirectly destroys CD4+ T cells. As CD4+ T cells are required for the proper functioning of the immune system, when enough CD4+ cells have been destroyed by HIV, the immune system barely works, leading to AIDS. HIV also directly attacks organs, such as the kidneys, the heart and the brain leading to acute renal failure, cardiomyopathy, dementia and encephalopathy. Many of the problems faced by people infected with HIV results from the failure of the immune system to protect them from opportunistic infections and cancers. HIV is transmitted through direct contact of a mucus membrane with a bodily fluid such as blood, semen, vaginal fluid or breast milk. This transmission can come in the form of: penetrative (anal or vaginal) sex; oral sex; blood transfusion; contaminated needles; exchange between mother and infant, during pregnancy, childbirth and breastfeeding; or other exposure to one of the above bodily fluids. AIDS is thought to have originated in sub-Saharan Africa during the twentieth century and it is now a global epidemic. At the end of 2004, UNAIDS estimated that nearly 40 million people were currently living with HIV. The World Health Organization estimated that the AIDS epidemic had claimed more than 3 million people and that 5 million people had acquired HIV in the same year. Currently it is estimated that 28 million people have died and that it is set to infect 90 million Africans alone, resulting in a minimum estimate of 18 million orphans in the African continent alone.

Introduction

In 1983, scientists led by Luc Montagnier at the Pasteur Institute in France first discovered the virus that causes AIDS (Barré-Sinoussi et al., 1983). They called it lymphadenopathy-associated virus (LAV). A year later, Robert Gallo and Marvin Reitz of the United States confirmed the discovery of the virus, and they named it human T lymphotropic virus type III (HTLV-III) (Popovic et al., 1984). In 1986, both names were dropped in favour of the term human immunodeficiency virus (HIV) (Coffin, 1986). HIV is a member of the genus lentivirus (ICTVdb, 61.0.6), part of the family of retroviridae (ICTVdb, 61). Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long duration illnesses associated with a long period of incubation (Lévy, 1993). Lentiviruses are transmitted as single-stranded negatively-sensed enveloped RNA viruses. Upon infection of the target-cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase which is present in the virus particle. This viral DNA is then integrated into the cellular DNA for replication using cellular machinery. Once the virus enters the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function or the virus becomes active, replicates and a large number of virus particles are liberated which can infect other cells. Two species of HIV infect humans: HIV-1 and HIV-2. HIV-1 is the more virulent and easily transmitted, and is the source of the majority of HIV infections throughout the world; HIV-2 is largely confined to west Africa (Reeves and Doms, 2002). Both species originated in west and central Africa, jumping from primates to humans in a process known as zoonosis. HIV-1 has evolved from a simian immunodeficiency virus (SIVcpz) found in the chimpanzee subspecies, Pan troglodyte troglodyte (Gao et al., 1999). HIV-2 crossed species from a different strain of SIV, found in sooty mangabey monkeys in Guinea-Bissau (Reeves and Doms, 2002).

Transmission

Since the beginning of the epidemic, three main transmission routes of HIV have been identified:
- Sexual route. The majority of HIV infections are acquired through unprotected sexual relations. Sexual transmission occurs when there is contact between sexual secretions of one partner with the rectal, genital or mouth mucous membranes of another. The probability of transmission per act is between 1 in 53 to 1 in 10,000 for the case of receptive vaginal sex (Pilcher et al., 2004), 1 in 8000 in the case of insertive vaginal sex, 1 in 1000 in the case of insertive anal sex, and between 1 in 100 to 1 in 30 in the case of receptive anal sex [http://thebody.com].
- Blood or blood product route. This transmission route is particularly important for intravenous drug users, hemophiliacs and recipients of blood transfusions and blood products. Health care workers (nurses, laboratory workers, doctors, etc) are also concerned, although more rarely. Also concerened by this route are people who give and receive tattoos and piercings.
- Mother-to-child route. The transmission of the virus from the mother to the child can occur in utero during the last weeks of pregnancy and at childbirth. Breast feeding also presents a risk of infection for the baby. In the absence of treatment, the transmission rate between the mother and child was 20%. However, where treatment is available, combined with the availability of Cesarian section, this has been reduced to 1%. HIV has been found in the saliva, tears and urine of infected individuals, but due to the low concentration of virus in these biological liquids, the risk is considered to be negligible. The use of physical barriers such as the latex condom is widely advocated to reduce the sexual transmission of HIV. Recently, it has been proposed that male circumcision may reduce the risk of HIV transmission (Siegfried et al., 2005), but many experts believe that it is premature to recommend male circumcision as part of HIV prevention programs (WHO, 2005). For more details on this topic, see AIDS prevention
The clinical course of HIV-1 infection
AIDS prevention Infection with HIV-1 is associated with a progressive loss of CD4+ T-cells. This rate of loss can be measured and is used to determine the stage of infection. The loss of CD4+ T-cells is linked with an increase in viral load. The clinical course of HIV-infection generally includes three stages: primary infection, clinical latency and AIDS (Figure 1). HIV plasma levels during all stages of infection range from just 50 to 11 million virions per ml (Piatak et al., 1993).
Primary Infection
Primary, or acute infection is a period of rapid viral replication that immediately follows the individual's exposure to HIV. During primary HIV infection, most individuals (80 to 90 %) develop an acute syndrome characterised by flu-like symptoms of fever, malaise, lymphadenopathy, pharyngitis, headache, myalgia, and sometimes a rash (Kahn and Walker, 1998). Within an average of three weeks after transmission of HIV-1, a broad HIV-1 specific immune response occurs that includes seroconversion. Because of the nonspecific nature of these illnesses, it is often not recognized as a sign of HIV infection. Even if patients go to their doctors or a hospital, they will often be misdiagnosed as having one of the more common infectious diseases with the same symptoms. Since not all patients develop it, and since the same symptoms can be caused by many other common diseases, it cannot be used as an indicator of HIV infection. However, recognizing the syndrome is important because the patient is much more infectious during this period
Clinical Latency
As a result of the strong immune defense, the number of viral particles in the blood stream declines and the patient enters clinical latency (Figure 1). Clinical latency is variable in length and can vary between two weeks and 20 years. During this phase HIV is active within lymphoid organs where large amounts of virus become trapped in the follicular dendritic cells (FDC) network early in HIV infection. The surrounding tissues that are rich in CD4+ T-cells also become infected, and viral particles accumulate both in infected cells and as free virus. Individuals who have entered into this phase are still infectious.
The declaration of AIDS
AIDS is the most severe manifestation of infection with HIV. Acute HIV infection progresses over time to clinical latent HIV infection and then to early symptomatic HIV infection and later, to AIDS, which is identified on the basis of certain infections. For more details on this topic, see AIDS symptomology.
HIV structure and genome
AIDS symptomology HIV is different in structure from previously described retroviruses. It is around 120 nm in diameter (120 billionths of a meter; around 60 times smaller than a red blood cell) and roughly spherical. HIV-1 is composed of two copies of single-stranded RNA enclosed by a conical capsid, which is in turn surrounded by a plasma membrane that is formed from part of the host-cell membrane. Other enzymes contained within the virion particle include reverse

Pre-ejaculate

Penis

Linguistics

Etymology

Synonyms

The human penis

Structure

Relation to female genitals

Erection

Size

Normal variations

Disorders affecting the penis

Developmental disorders of the penis

Penis replacement

Alleged and observed penis-related psychological disorders

Altering the male genitalia

Fears and reassurance

Non-human penises

Cultural aspects involving penises

Uses of animal penises

Uses of human penises in cultural traditions

See also

External links

Cowper's gland

Structure

Foreplay

See also

Orgasm

General

Shared physiology

Human male orgasm

Male prostate orgasm

Male multiple orgasms

Human female orgasm

The evolutionary purpose of orgasms

Orgasm as vestigial

Genetic basis of individual variation

Vaginal versus clitoral orgasms

Controversy: definition of orgasm

Orgasm in post-operative transsexuals

Transwomen

Transmen

Orgasmic dysfunction

Drugs and orgasm

Orgasm in Tantric sex

Orgasm in non-humans

Non-sexual meaning of the word "orgasm"

See also

External links

References

Urethra

Anatomy

Histology

Medical problems of the urethra

Related topics

Foreskin

The human foreskin

Description

Development

Functions

Conditions

Surgical and other modifications of the foreskin

- Statistics

See also

External links

Glans penis

Medical considerations

Anatomical details

See also

External links

Pregnancy

Detection and dating

Timeline of a typical pregnancy

First trimester

Fertilization

Implantation

Second trimester

Third trimester

Medical aspects of pregnancy

Birth