rectum


rectum
/rek"teuhm/, n., pl. rectums, recta /-teuh/. Anat.
the comparatively straight, terminal section of the intestine, ending in the anus. See diag. under intestine.
[1535-45; < NL rectum (intestinum) the straight (intestine)]

* * *

End segment of the large intestine (see digestion) in which feces accumulate just prior to discharge.

It is 5–6 in. (13–15 cm) long and lined with mucous membrane. One set of muscles separates it from the anal canal; another shortens it to expel feces. The rectal walls distend as feces enter, which stimulates the urge for defecation.

* * *

      terminal segment of the digestive system (digestive system, human) in which feces accumulate just prior to discharge. The rectum is continuous with the sigmoid colon and extends 13 to 15 cm (5 to 6 inches) to the anus. A muscular sheet called the pelvic diaphragm runs perpendicular to the juncture of the rectum and anal canal and maintains a constriction between these two segments of the large intestine. The internal cavity of the rectum is divided into three or four chambers; each chamber is partly segmented from the others by permanent transverse folds (valves of Houston) that help to support the rectal contents. A sheath of longitudinal muscle surrounds the outside wall of the rectum, making it possible for the rectum to shorten in length.

      Food wastes remain in the sigmoid colon until they are ready to be excrete (defecation)d from the body. As the fecal material enters the rectum, the walls distend to accommodate the material. When sufficient pressure builds up within the distended rectal cavity, the urge to eliminate wastes occurs. When receptors of the nervous system within the rectal wall are stimulated by its stretching, they send impulses to the anal canal, chest and abdominal-wall muscles, and the medulla oblongata of the brain, which makes the individual conscious of the need to defecate. See also defecation.

* * *


Universalium. 2010.

Look at other dictionaries:

  • rectum — [ rɛktɔm ] n. m. • av. 1478; lat. méd. pour rectum intestinum « intestin droit » ♦ Portion terminale du gros intestin, faisant suite au côlon pelvien et s étendant jusqu à l anus. Étude des maladies de l anus et du rectum. ⇒ proctologie. ● rectum …   Encyclopédie Universelle

  • rectum — early 15c., from L. intestinum rectum straight intestine, in contrast to the convolution of the rest of the bowels, from neut. pp. of regere to straighten (see RIGHT (Cf. right)). A loan translation of Gk. apeuthysmeon enteron, the name given to… …   Etymology dictionary

  • rectum — ► NOUN (pl. rectums or recta) ▪ the final section of the large intestine, terminating at the anus. ORIGIN from Latin rectum intestinum straight intestine …   English terms dictionary

  • rectum — [rek′təm] n. pl. rectums or recta [rek′tə] [ModL < L rectum (intestinum), lit., straight (intestine) < rectus: see RECTI ] the lowest, or last, segment of the large intestine, extending, in humans, from the sigmoid flexure to the anus: see… …   English World dictionary

  • Rectum — Rec tum ( t?m), n. [NL. (sc. intestinum), fr. L. rectus straight. See {Right}.] (Anat.) The terminal part of the large intestine; so named because supposed by the old anatomists to be straight. See Illust. under {Digestive}. [1913 Webster] …   The Collaborative International Dictionary of English

  • Rectum — Rectum, der Mastdarm, s.d …   Pierer's Universal-Lexikon

  • Rectum — (lat.), der Mastdarm, s. Darm …   Meyers Großes Konversations-Lexikon

  • Rectum — (nämlich intestīnum, lat.), der Mastdarm …   Kleines Konversations-Lexikon

  • Rectum — Rectum, s. Mastdarm …   Herders Conversations-Lexikon

  • Rectum — ⇒ Mastdarm …   Deutsch wörterbuch der biologie

  • rectum — RÉCTUM s.n. v. rect. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.