rectum - Medical procedures, The rectum in human defecation, Sexual stimuli

That part of the gastro-intestinal tract between the sigmoid colon and the anal canal. When gastro-intestinal contents enter the rectum, the individual has the urge to defaecate. Partial (mucous membrane and submucosa layer) or complete (whole thickness of the rectal wall) prolapse of the rectum is relatively common, and has many causative factors (eg muscle damage during childbirth, poor muscle tone in the elderly).

Medical procedures

For the diagnosis of certain ailments, a rectal exam may be done.

Body temperature can also be taken in the rectum. Rectal temperature can be taken by inserting a mercury thermometer for 3 to 5 minutes, or a digital thermometer until it "beeps", not more than 25 mm (1 inch) into the rectum via the anus. Normal rectal temperature generally ranges from 36 to 38 °C (97.6 to 100.4 °F) and is about 0.5 °C (1 °F) above oral (mouth) temperature and about 1 °C (2 °F) above axillary (armpit) temperature. On average, the rectal temperature is 0.4 °C (0.7 °F) higher than oral temperature. Many pediatricians recommend that parents take infants and toddler's temperature in the rectum for two reasons: (1) Rectal temperature is the closest to core body temperature and in children that young, accuracy is critical. (2)Younger children are unable to cooperate when having their temperature taken by mouth (oral) which is recommended for children, ages 6 and above and for adults. In recent years, the introduction of ear (tympanic) thermometers and changing attitudes on privacy and modesty have led some parents and doctors to discontinue taking rectal temperatures.

The rectum in human defecation

The rectum ampulla acts as a temporary storage facility for feces. As the rectal walls expand due to the materials filling it from within, stretch receptors from the nervous system located in the rectal walls stimulate the desire to defecate.

When the rectum is full the 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 propel the feces out of the rectum.

Sexual stimuli

Due to the proximity of the anterior wall of the rectum to the vagina in females or to the prostate in males and the shared nerves thereof, rectal stimulation can result in sexual arousal.