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Anatomy of the anus and rectum

Defecation is the final act of digestion, by which organisms eliminate solid, semisolid, and/or liquid waste material from the digestive tract via the anus.

Humans expel feces with a frequency varying from a few times daily to a few times weekly.[1] Waves of muscular contraction (known as peristalsis) in the walls of the colon move fecal matter through the digestive tract towards the rectum. Undigested food may also be expelled this way, in a process called egestion.

Open defecation is the practice of defecating outside or in public, i.e. without using a toilet of any kind, something that is still widespread in many developing countries, including for example in India, Indonesia, Pakistan and Nigeria.[2]



The rectum ampulla (anatomically also: ampulla recti) temporarily stores fecal waste. As the waste fills the rectum and expands the rectal walls, nervous system stretch receptors in the rectal walls stimulate the desire to defecate. This urge to defecate arises from the reflex contraction of rectal muscles, relaxation of the internal anal sphincter, and an initial contraction of the skeletal muscle of the external anal sphincter. If the urge is not acted upon, the material in the rectum is often returned to the colon by reverse peristalsis, where more water is absorbed and the faeces is stored until the next mass peristaltic movement of the transverse and descending colon. If defecation is delayed for a prolonged period the fecal matter may harden, resulting in constipation. If defecation occurs too fast, before excess liquid is absorbed, diarrhea may occur.[3]

When the rectum is full, an increase in intra-rectal pressure forces apart the walls of the anal canal, allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic waves push the feces out of the rectum. The internal and external anal sphincters along with the puborectalis muscle allow the feces to be passed by muscles pulling the anus up over the exiting feces.[citation needed]

Defecation is normally assisted by taking a deep breath and trying to expel this air against a closed glottis (Valsalva maneuver). This contraction of expiratory chest muscles, diaphragm, abdominal wall muscles, and pelvic diaphragm exerts pressure on the digestive tract. Ventilation at this point temporarily ceases as the lungs push the chest diaphragm down to exert the pressure. Thoracic blood pressure rises and as a reflex response the amount of blood pumped by the heart decreases. Death has been known to occur in cases where defecation causes the blood pressure to rise enough to cause the rupture of an aneurysm or to dislodge blood clots (see thrombosis). Also, in releasing the Valsalva maneuver blood pressure falls; this, coupled with standing up quickly to leave the toilet, can result in a blackout.[citation needed] [4]

When defecating, the external sphincter muscles relax. The anal and urethral sphincter muscles are closely linked. Experiments by Dr. Harrison Weed at the Ohio State University Medical Center have shown they can only be contracted together, not individually, and that both show relaxation during urination[citation needed]. This explains why defecation is frequently accompanied by urination.

Voluntary and involuntary control[edit]

Defecation may be involuntary or under voluntary control.  Young children learn voluntary control through the process of toilet training.  Once trained, loss of control called fecal incontinence, may be caused by physical injury, nerve injury, prior surgeries (such as an episiotomy), constipation, diarrhea, loss of storage capacity in the rectum, intense fright, inflammatory bowel disease, psychological or neurological factors, birth, or death.[5]

Anal cleansing after defecation[edit]

Main article: Anal cleansing

The anus and buttocks may be cleansed after defecation with toilet paper, similar paper products, or other absorbent material. In many cultures, such as Muslim and Hindu cultures, water is used for anal cleansing after defecation, either in addition to using toilet paper or exclusively. When water is used for anal cleansing after defecation, toilet paper may be used for drying the area afterwards.


The positions and modalities of defecation are culture-dependent. Squat toilets are used by the vast majority of the world, including most of Africa, Asia and the Middle East.[6] The use of sit-down toilets in the Western world is a recent development, beginning in the 19th century with the advent of indoor plumbing.[7]

Society and culture[edit]

Mythology and tradition[edit]

The caganer is a defecating figurine in Spanish Nativity scenes

Some peoples have culturally significant stories in which defecation plays a role. In a Wemale and Alune legend from the island of Seram, Maluku Province, Indonesia, the mythical girl Hainuwele defecates valuable objects.[8] One of the traditions of Catalonia (Spain) relates to the Caganer, a figurine depicted in the act of defecation appearing in nativity scenes in Catalonia and neighbouring areas with Catalan culture. The exact origin of the Caganer is lost, but the tradition has existed since at least the 18th century.[9]

See also[edit]


  1. ^ "A description of Normal Bowel Movements". 30 September 2013. Retrieved 29 November 2013. 
  2. ^ JMP (2014). Progress on drinking water and sanitation, 2014 Update. WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation (JMP), ISBN 978 92 4 150724 0, page 19.
  3. ^ NIH. "Bowel Movement". Medline. Retrieved 13 September 2014. 
  4. ^ [Cardio-vascular Events at Defecation: Are They Unavoidable? - Medical Hypotheses, Jul 1990, 32(3):231-3]
  5. ^ "Fecal incontinence - Causes". Mayo Foundation for Medical Education and Research. Retrieved 9 September 2014.  |first1= missing |last1= in Authors list (help)
  6. ^ Kira A. The Bathroom. Harmondsworth: Penguin, 1976, revised edition, pp.115,116.
  7. ^ A History of Technology, Vol.IV: The Industrial Revolution, 1750-1850. (C. Singer, E Holmyard, A Hall, T. Williams eds) Oxford Clarendon Press, pps. 507-508, 1958
  8. ^ The Oxford Companion to World Mythology - Hainuwele
  9. ^ "A traditional Nativity scene, Catalan-style". BBC News. 23 December 2010. Retrieved 23 December 2010. 

Further reading[edit]

  • Deeb, Benjamin (2004). Healthy to the Core: How to Measure Effective Defecation. Greenwood Press.
  • Widmaier, Raff & Strang (2006). Vanders' Human Physiology, the mechanisms of body function. Chapter 15. McGraw Hill.

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Defecation — Please support Wikipedia.
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38247 news items

The Hindu
Thu, 28 Apr 2016 17:11:15 -0700

The Mysuru City Corporation had the onus of freeing the wards in its limits from open defecation and it recently secured declaration on the extent of use of toilets by children in schools and in the households besides the residents from the respective ...


Thu, 28 Apr 2016 10:48:45 -0700

“When one hears the unwillingness to stop open defecation, it is worrying. This disposal of fecal matter through inappropriate ways leads to incidents of sanitation-related risks, including cholera, dysentery, which have socio-economic consequences on ...


Times of India (blog)
Wed, 27 Apr 2016 11:05:41 -0700

A recent rapid survey conducted by the National Sample Survey Office (NSSO) on the Swachh Bharat Mission has raised a big question mark on the latter's ability to realise the goal of an Open Defecation Free (ODF) India by 2019. As the survey points out ...
Times of India
Thu, 28 Apr 2016 20:45:00 -0700

Sources said that to the civic body will also have to invite objections and suggestions from citizens before declaring these wards free of open defecation. VMC has already published a notification inviting objections and suggestions for these five wards.
Times of India
Tue, 26 Apr 2016 14:06:17 -0700

Belagavi: The Belagavi City Corporation (BCC) has launched a drive to make the city open defecation free. Taking the first step in the direction, officials are creating awareness among slum-dwellers and residents of other backward areas. Officials are ...
Times of India
Sun, 24 Apr 2016 11:54:37 -0700

"All engineers of DUSIB were asked to visit slums and its surroundings to identify common open defecation spots between 5am to 8am on two non-working days—Ram Navami and Mahavir Jayanti. They were asked to record not just the sites but also capture ...

The Hindu

The Hindu
Thu, 21 Apr 2016 01:47:01 -0700

More than half the rural population of the country still opts for open defecation, says the recently released Swachhta Status Report by the National Sample Survey (NSS) Office. The nation-wide rapid survey was conducted during May-June 2015 ...
Chandigarh Tribune
Wed, 20 Apr 2016 13:58:45 -0700

In order to make the city open defecation-free (ODF) and to create awareness among residents, the Chandigarh Municipal Corporation has formed 38 teams and nominated the same number of 'swachhata doots' to spread awareness among the residents.

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