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'{{Hatnote|See also [[Defecation (band)]], [[defector]], and [[defalcation]].}} {{pp-pc1|small=yes}} {{Refimprove|date=March 2008}} [[Image:Anorectum.gif|right|frame|Anatomy of the anus and rectum]] '''Defecation''' is the final act of [[digestion]], by which organisms eliminate solid, semisolid, or liquid [[waste]] material from the [[digestive tract]] via the [[anus]]. [[Human]]s expel [[human feces|feces]] with a frequency varying from a few times daily to a few times weekly.<ref name="About.com">{{cite web|url=http://ibdcrohns.about.com/od/dailylife/a/normalbm.htm|title=A description of Normal Bowel Movements |date=30 September 2013|accessdate=29 November 2013|website=About.com}}</ref> Waves of [[muscle|muscular contraction]] (known as ''[[peristalsis]]'') in the walls of the [[colon (anatomy)|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]], the practice of defecating outside without using a [[toilet]] of any kind, is still widespread in some [[developing countries]], including, for example, India, Indonesia, Nigeria, and Pakistan.<ref name=":3">{{cite journal|journal=JMP |date=2014|url=http://www.wssinfo.org/fileadmin/user_upload/resources/JMP_report_2014_webEng.pdf |title=Progress on drinking water and sanitation, 2014 Update|author= WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation |isbn= 978 92 4 150724 0| page =19}}</ref> ==Description== ===Physiology=== The [[Rectal ampulla|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.<ref>{{cite news|journal=Medline|url=https://www.nlm.nih.gov/medlineplus/bowelmovement.html|author=NIH||title=Bowel Movement|accessdate=13 September 2014}}</ref> it basically shit 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|date=February 2013}} 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 (anatomy)|diaphragm]], abdominal wall muscles, and [[pelvis|pelvic]] diaphragm exerts pressure on the digestive tract. [[Ventilation (physiology)|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|date=February 2013}} <ref>[Cardio-vascular Events at Defecation: Are They Unavoidable? - Medical Hypotheses, Jul 1990, 32(3):231-3]</ref> During defecation, the external sphincter muscles relax. The anal and [[urethral sphincter]] muscles are closely linked. Experiments by 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|date=December 2007}} This explains why defecation is frequently accompanied by [[urination]]. ===Voluntary and involuntary control=== Defecation may be involuntary or voluntary.&nbsp; Young children learn voluntary control through the process of [[toilet training]].&nbsp; 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, [[childbirth]], or [[death]].<ref>{{cite web|author=<!--Staff writer(s); no by-line.--> |title=Fecal incontinence - Causes|url=http://www.mayoclinic.org/diseases-conditions/fecal-incontinence/basics/causes/con-20034575|publisher=Mayo Foundation for Medical Education and Research|accessdate=9 September 2014}}</ref> ==Anal cleansing after defecation== {{main article|Anal cleansing}} The [[anus]] and [[buttocks]] may be [[anal cleansing|cleansed]] after defecation with [[toilet paper]], similar paper products, or other absorbent material. In many cultures, such as Hindu and Muslim, 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. ==Posture== {{main article|Human defecation postures}} The positions and modalities of defecation are [[Culture#Cultures by region|culture-dependent]]. [[Squat toilet]]s are used by the vast majority of the world, including most of Africa, Asia, and the Middle East.<ref>{{cite book|last1=Kira|first1=Alexander|title=The Bathroom|date=1976|publisher=Viking Pr|location=New York, N.Y.|isbn=0-670-00612-2|pages=115–116|edition=2. ed. New and expanded}}</ref> The use of sit-down [[toilet]]s in the [[Western world]] is a relatively recent development, beginning in the 19th century with the advent of indoor plumbing.<ref>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</ref> == Society and culture == ===Mythology and tradition=== [[File:Caganer back.png|thumb|160px|The ''[[caganer]]'' is a defecating figurine in Spanish [[Nativity scene]]s]] Some peoples have culturally significant stories in which defecation plays a role. For example: *In an [[Alune people|Alune]] and [[Wemale]] legend from the island of [[Seram]], [[Maluku Islands|Maluku Province]], [[Indonesia]], the mythical girl [[Hainuwele]] defecates valuable objects.<ref>{{cite news|url=http://www.oxfordreference.com/view/10.1093/acref/9780195156690.001.0001/acref-9780195156690-e-657 |work=The Oxford Companion to World Mythology |title= Hainuwele|isbn=9780195156690}}</ref> *One of the [[traditions of Catalonia]] ([[Spain]]) relates to the ''[[Caganer]]'', a [[figurine]] depicting the act of defecation which appears in [[nativity scene]]s in [[Catalonia]] and neighbouring [[Catalan Countries|areas with Catalan culture]]. The exact origin of the ''Caganer'' is lost, but the tradition has existed since at least the 18th century.<ref name="BBC News">{{cite web|url=http://www.bbc.co.uk/news/world-europe-12059969|title=A traditional Nativity scene, Catalan-style|website=BBC News |date=23 December 2010|accessdate=23 December 2010}}</ref> ==See also== {{div col|colwidth=30em}} *''[[Artist's Shit]]'' *[[Constipation]] *[[Hemorrhoid]] * [[Rectal tenesmus]] - a feeling of incomplete defecation *[[Shit]] {{div col end}} ==References== {{lacking ISBN|date=February 2017}} {{Reflist|30em}} ==Further reading== {{lacking ISBN|date=February 2017}} *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. {{Digestive system and abdomen symptoms and signs}} {{toilets}} [[Category:Digestive system]] [[Category:Colorectal surgery]] [[Category:Medical signs]] [[Category:Feces]] [[Category:Excretion]] [[Category:Symptoms and signs: Digestive system and abdomen]]'