defecate

　

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1. 排便する

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/05/15 22:44:27」(JST)

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"Bowel movement" redirects here. For the death metal band, see Defecation (band).

Anatomy of the anus and rectum

Defecation (colloquially known as a bowel movement or bm) is the final act of digestion, by which organisms eliminate solid, semisolid, and/or liquid waste material (feces) from the digestive tract via the anus.

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

Description

Physiology

The rectum ampulla (anatomically also: ampulla recti) acts as a temporary storage facility for the unneeded material. As the rectal walls expand due to the material filling it, stretch receptors from the nervous system located 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.

When the rectum is full, an increase in intra-rectal pressure forces the walls of the anal canal apart 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 exert 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, commonly results in the incidence of blackouts.^{[citation needed]}

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 they both show relaxation during urination^{[citation needed]}. This explains why defecation is frequently accompanied with urination.

Vouluntary and involuntary control

Defecation may be involuntary or under voluntary control. Young children learn voluntary control through the process of toilet training. Once trained, loss of control, causing fecal incontinence, may be caused by physical injury (such as damage to the anal sphincter that may result from an episiotomy), intense fright, inflammatory bowel disease, impaired water absorption in the colon (see diarrhea), and psychological or neurological factors.^{[citation needed]}

Cleansing

The anus and buttocks may be cleansed with toilet paper, similar paper products, or other absorbent material. In some cultures water is used (e.g., as with a bidet) either in addition or exclusively. In Japan and South Korea, some toilets known as washlets are designed to wash and dry the user's anus after defecation (see anal cleansing).

Posture

Main article: Human defecation postures

Defecation in squatting position

The positions and modalities of defecation are culture-dependent. The natural and instinctive method used by all primates, including humans, is the squatting position. Squat toilets are still used by the vast majority of the world, including most of Africa, Asia and the Middle East. The widespread use of sit-down toilets in the Western World is a recent development, beginning in the 19th century with the advent of indoor plumbing.

Bockus' Gastroenterology, the standard textbook on the subject, states:

The ideal posture for defecation is the squatting position, with the thighs flexed upon the abdomen. In this way the capacity of the abdominal cavity is greatly diminished and intra-abdominal pressure increased, thus encouraging the expulsion of the fecal mass.

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Mythology and tradition

Some people groups 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.

One of the traditions of Catalonia (Spain) is 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. Another Catalan Christmas tradition associated with defecation is the Tió de Nadal.

In Japan, it is said that visiting a bookstore for a while perhaps has a laxative effect. The effect is called Mariko Aoki phenomenon.

See also

• Toilet god

Notes

References

• 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.

UpToDate Contents

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• 1. 運動選手における消化器疾患 gastrointestinal disorders in athletes
• 2. 幼児および小児における慢性機能性便秘および便失禁の治療 treatment of chronic functional constipation and fecal incontinence in infants and children
• 3. 膣後壁欠損の臨床症状、診断、および非外科的マネージメント clinical manifestations diagnosis and nonsurgical management of posterior vaginal defects
• 4. 幼児および小児における機能性便失禁の定義、臨床症状、および評価 definition clinical manifestations and evaluation of functional fecal incontinence in infants and children
• 5. 成人における便失禁 fecal incontinence in adults

English Journal

• Urination and defecation by group-housed dairy calves.

• Vaughan A1, de Passillé AM2, Stookey J3, Rushen J2.
• Journal of dairy science.J Dairy Sci.2014 Jul;97(7):4405-11. doi: 10.3168/jds.2013-7558. Epub 2014 May 10.
• A better understanding of when and where group-housed calves are most likely to defecate or urinate might permit improved housing design or more efficient use of cleaning routines. However, this is the first study to address the urination and defecation habits of calves. The primary aims of this stu
• PMID 24819136

• Elimination communication as colic therapy.

• Jordan GJ.
• Medical hypotheses.Med Hypotheses.2014 Jun 7. pii: S0306-9877(14)00222-9. doi: 10.1016/j.mehy.2014.05.018. [Epub ahead of print]
• Colic is generally defined as excessive crying in early infancy and can have negative consequences on the infant as well as on the infant's family life. Excessive crying can result in escalating parental stress levels, abusive caregiver response, increased risk of shaken baby syndrome and parental p
• PMID 24962210

• The efficacy of education programme for preventing constipation in women.

• Ayaz S1, Hisar F.
• International journal of nursing practice.Int J Nurs Pract.2014 Jun;20(3):275-82. doi: 10.1111/ijn.12144. Epub 2013 Aug 15.
• This study was performed to evaluate the efficiency of the education programme for prevention of constipation in women. This study was performed as a pre-test-posttest design. Thirty-five women were included who have constipation problem. Data were collected by questionnaire: Constipation Severity I
• PMID 24889000

Japanese Journal

• 子どもの家庭における食生活の実態と学校給食による調査(1)排便と食物繊維の摂取について

• 森山 克子,與那覇 由里,Moriyama Katsuko,Yonaha Yuri
• 琉球大学教育学部紀要 82, 253-259, 2013-03
• … The result shows that there is no significant differences the amount of intaking dietary fiber and actual situation of defecate. … For male students， the more they intake dietary fiber，the worse actual situation of defecate is. … For female students，the lesser they inkate dietary fiber，the worse状況(frequency，quality) of defecate. …
• NAID 120005294291

• Defecation-related Asthma

• Ano Satoshi,Morishima Yuko,Ishii Yukio,Kawaguchi Mio,Matsuno Yosuke,Hizawa Nobuyuki
• Internal Medicine 52(6), 685-687, 2013
• … We herein report the case of a 39-year-old man with recurrent asthma exacerbations preceded by abdominal cramps with the urge to defecate. … He stated that, even when his daily asthma symptoms were under control, he suffered from attacks, especially when he had a strong urge to defecate. …
• NAID 130003365949

• メコン河のメコン住血吸虫症と中間宿主貝

• 松田 肇
• 衛生動物 63(4), 269-276, 2012
• … Inhabitants of the lower Mekong tend to rise early to bathe, defecate, wash and work on the river bank, children join their parents.This paper on Mekong schistosomiasis and the intermediate host snail in the Mekong region consists of discussion on the parasitic disease in the past, present epidemiology, malacology, transmission dynamics, control implementation, application of immunodiagnosis for epidemiology and difference in the schistosomiasis problems of Laos and Cambodia. …
• NAID 130004559024

Related Links

• defecateの意味 - 英和辞書 - goo辞書

defecateとは。意味や和訳。((形式))[動](自)排便する；かす[不純物]が除かれる. (他)〈かす・不純物を〉除く.degrave;f・e・ca・tion[名] - goo辞書は国語、英和、和英、中国語、百科事典等からまとめて探せる辞書検索サービスです。

• defecateの意味・用例｜英辞郎 on the WEB：アルク

defecate 【自動】 排便する・A puppy wants to defecate soon after a meal. : ... - アルクがお届けする進化するオンライン英和・和英辞書データベース。一般的な単語や連語から、イディオム、専門用語、スラングまで幅広く収録。

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