Defecation

:For the death metal band Defecation, see Defecation . Defecation is the act or process by which organisms eliminate solid or semisolid 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; sloths can go a week without expelling. 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; this process is called egestion.The rectum ampulla 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. If the urge is not acted upon, the material in the rectum is often returned to the colon where more water is absorbed. If defecation is delayed for a prolonged period the fecal matter may harden, resulting in constipation.When the rectum is full, an increase in intrarectal 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 allow the feces to be passed by muscles pulling the anus up over the exiting feces. During defecation the chest muscles, diaphragm, abdominal wall muscles, and pelvic diaphragm all exert pressure on the digestive tract and ventilation temporarily ceases as the lungs push the chest diaphragm down in order to exert pressure. Blood pressure rises throughout the body and the amount of blood pumped by the heart decreases. During this time, the body is effectively undergoing similar stresses to that of a valsalva maneuver. 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 . Humans must consciously relax the external sphincter muscles to expel waste. The anal and urethal sphincter muscles are closely linked, and experiments by Dr. Harrison Weed at the Ohio State University Medical Center have shown that they can only be contracted together, not individually, and that they both show relaxation during urination. This explains why defecation is frequently accompanied with urination.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 , intense fright, inflammatory bowel disease, impaired water absorption in the colon , and psychological or neurological factors. The positions and modalities of defecation are culture-dependent. In some regions of the world, such as South Asia, East Asia and rural parts of the Middle East, it is customary to squat , while in most of the Western World sit-down toilets are used. The anus and buttocks may be cleansed with toilet paper or similar paper products. In some cultures water is also used . In Japan, some toilets known as washlets are designed to wash and dry the anus of the user after defecation. (From the Wikpedia article Defecation.)

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Recent Publications on Defecation:
Late morbidity following nerve-sparing radical hysterectomy. OBJECTIVES: Nerve-sparing (NS) modification of radical hysterectomy (RH)...	13th November, 2009	Oncogynecological Center, Department of Obstetrics and Gynecology, General	Gynecol Oncol. 2009 Nov 9. DOI Direct Link
[The historical change of meanings about "Guan-Ge"] The meaning of Guan-Ge has changed through history. Former research about...	13th November, 2009	Kotaka Clinic for Integrated Medicine.	Nippon Ishigaku Zasshi. 2009 Mar;55(1):57-75.
[Selective fenestration lamina of cervical vertebral lamina to excise ligamentum flavum for treating hypertrophic ligamentum flavum] OBJECTIVE: To explore operative method and clinical effect of selective...	12th November, 2009	Department of Orthopaedics, the Central Hospital of Quzhou, Quzhou 324000,	Zhongguo Gu Shang. 2009 Oct;22(10):741-3.
Bowel movements of normal Thai infants. The aim of this study was to define the bowel movements of healthy Thai...	11th November, 2009	Department of Pediatrics, Faculty of Medicine, Princess Maha Chakri	Southeast Asian J Trop Med Public Health. 2009 May;40(3):530-7.
Peripheral peptide YY inhibits propulsive colonic motor function through Y2 receptor in conscious mice. Peptide YY (PYY) antisecretory effect on intestinal epithelia is well...	7th November, 2009	1UCLA.	Am J Physiol Gastrointest Liver Physiol. 2009 Nov 5. DOI Direct Link
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BioNews Results for Defecation:
ACG: Mixed Findings on Frequency of Dyssynergic Defecation	MedPage Today:  Oct 27 2009 9:49PM Matching: defecation

Defecation Clinical Trials:
Study of Stapled Transanal Rectal Resection (STARR) Surgery in Refractory Constipation Associated With Obstructive Defecation Syndrome (ODS)

Defecation Patents:
US Patent No.	Title
7458961	Thong-shaped holder for use with absorbent article
7494979	Method for treating congestive heart failure and other disorders
7497351	Wet wipe dispensing system
7501137	Process for controlling fecal hair excretion and trichobezoar formation
7504251	Bacterial strain, processed plant extracts, compositions containing same, processes for their preparation and their therapeutic and industrial applications
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