LARGE INTESTINE

• Large intestine - portion of the digestive tract extending from the ileocecal junction to the anus
• Parts of the large intestine:

  • Cecum
  • Colon
  • Rectum
  • Anal canal
• 18-24 hours are required for material to pass through the large intestine, compared to 3-5 hours required for chyme to move through the small intestine
• 1500 mL of chyme enter the cecum each day, but more than 90% of the volume is reabsorbed, so that 80-150 mL of feces are normally eliminated by defecation
• Cecum - proximal end of the large intestine, where it meets the small intestine at the ileocecal junction
• Vermiform appendix - a smaller, blind tube about 9 cm long attached to the cecum
• Colon - 1.5-1.8 m long, consists of 4 parts:

  • Ascending colon - cecum to right colic flexure
  • Transverse colon - right colic flexure to left colic flexure
  • Descending colon - left colic flexure to superior opening of true pelvis
  • Sigmoid colon - S-shaped tube that extends from pelvis to the rectum
• Rectum - straight, muscular tube that begins at the distal end of the sigmoid colon and ends at the anal canal; lined with simple columnar epithelium
• Anal canal - last 2-3 cm of the digestive tract; begins at inferior end of the rectum and ends at the anus
• Hemorrhoids - enlarged or inflamed rectal veins in the anal canal