Intestine — Tashrih

Step 1

Choose an organ

Step 2

Duodenum: First small-intestine segment
Jejunum: Major absorption region
Ileum: Final stretch — reclaims bile salts and vitamin B12
Caecum: Pouch where small meets large intestine
Appendix: A reservoir for gut bacteria, not a useless remnant
Ascending Colon: Climbs the right side
Transverse Colon: Crosses beneath the stomach
Colon: Reclaims water
Descending Colon: Runs down the left side
Sigmoid Colon: S-shaped final bend
Rectum: Holding chamber, with the only voluntary control in the tract
Duodenojejunal flexure: Slung from the diaphragm by the suspensory muscle of Treitz — the fixed point where the retroperitoneal duodenum becomes mobile jejunum
Ileocaecal junction: The one-way door into the colon — it meters the ileum's output and keeps a colon full of bacteria from backing up into the small bowel
Right colic flexure: The bend under the liver where the ascending colon turns left — held down by the paracolic gutter behind it
Left colic flexure: Higher and sharper than the right, tucked under the spleen — the watershed between the two mesenteric arteries
Taeniae coli: Three longitudinal muscle ribbons, shorter than the colon itself — their pull gathers the wall into haustra
Anal canal: Four centimetres of double control — the pectinate line divides visceral sensation above from somatic pain below

Step 3

Microscopic view

Compare organs

Function animation

Clinical notes

A rigid, board-like abdomen with no bowel sounds is peritonitis — a perforation has soiled the cavity.
Rectal bleeding with weight loss or a changed bowel habit past forty-five earns a colonoscopy, not reassurance.
Colicky pain, distension, vomiting, and absolute constipation — the gut is blocked and may strangulate.

Where it works

A tube from mouth to end, plus the glands that feed into it, dismantling food into pieces small enough to absorb.

Also in this system