Tashrih
System

Digestive System

Placing the digestive system8%

A river with a chemistry setSystema digestorium

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

Illustrated plate of the digestive system
Primary role
Breaks down food and absorbs nutrients
Scale
About 9 m end to end
Every day
Secretes around 7 L of fluid

Organs in this atlas 2

How it works as a whole

The digestive tract is topologically outside the body — a tunnel passing through it — which is why its contents must be actively transported across a lining to truly enter you. Food is broken down mechanically and then chemically, in stages, each with its own pH and its own enzymes. The liver and pancreas do not carry food themselves but pour bile and enzymes into the stream and then process what is absorbed. Everything drained from the gut goes to the liver first, before the rest of the body sees it.

Other key structures

  • StomachAcid bath and mixing chamber; begins protein digestion
  • GallbladderStores and concentrates bile until fat arrives
  • OesophagusMuscular tube that pushes food down by wave, not gravity
  • Gut microbiomeTrillions of microbes fermenting what human enzymes cannot

Connected systems

  • Endocrine SystemGut hormones and pancreatic islets set hunger and blood sugar
  • Cardiovascular SystemThe portal vein routes all absorbed nutrients to the liver first
  • Nervous SystemThe enteric nervous system talks constantly to the brain

Common conditions

  • Reflux disease
  • Inflammatory bowel disease
  • Coeliac disease
  • Gallstones
  • Cirrhosis
  • Pancreatitis

The through-lineThe gut runs its own nervous system — hundreds of millions of neurons in the intestinal wall — which coordinates digestion largely without the brain, and sends far more signals upward than it receives.

Did you knowThe stomach lining replaces itself every few days — otherwise it would digest itself along with lunch.

The path through this system

0 of 20 steps done — read it, walk it in 3D, then be asked about it.

Start: Intestine: the lesson
ReadLessonIntroIntestine: the lesson

Structure and story of the intestine, layer by layer.

3 minReadLessonIntroLiver: the lesson

Structure and story of the liver, layer by layer.

3 minGuided walk-throughDissectionIntroGuided dissection: intestine

Walk the intestine structure by structure, then cut inward layer by layer.

6 minGuided walk-throughDissectionIntroGuided dissection: liver

Walk the liver structure by structure, then cut inward layer by layer.

6 minMemo cardsQuizIntroIntestine memo cards

Turn the cards on the intestine — structures, layers, key facts — and grade yourself.

4 minTrue or falseQuizIntroIntestine myths, busted

Common claims about the intestine, put to the test.

2 minMultiple choiceQuizIntroIntestine quiz

A multiple-choice round on the intestine, reshuffled every time.

4 minMemo cardsQuizIntroLiver memo cards

Turn the cards on the liver — structures, layers, key facts — and grade yourself.

4 minMultiple choiceQuizIntroLiver quiz

A multiple-choice round on the liver, reshuffled every time.

4 minMultiple choiceQuizCoreDigestive System quiz

A quiz pulling from every organ in the digestive system.

4 minClick on the 3D modelQuizCoreFind the intestine structures

Click the named structures directly on the live 3D intestine.

5 minClick on the 3D modelQuizCoreFind the liver structures

Click the named structures directly on the live 3D liver.

5 minMatch layersQuizCoreMatch intestine layers

Pair each layer of the intestine, outside in, with what it does.

4 minMatch pairsQuizCoreMatch intestine structures

Pair each structure in the intestine with its role.

4 minMatch layersQuizCoreMatch liver layers

Pair each layer of the liver, outside in, with what it does.

4 minMatch pairsQuizCoreMatch liver structures

Pair each structure in the liver with its role.

4 minPut in orderQuizAdvancedOrder the intestine's blood flow

Trace blood through the intestine in the order it actually flows.

4 minPut in orderQuizAdvancedOrder the liver's blood flow

Trace blood through the liver in the order it actually flows.

4 minReadClinicalIntroIntestine in the clinic

Where the intestine shows up in the clinic, and what goes wrong.

3 minReadClinicalIntroLiver in the clinic

Where the liver shows up in the clinic, and what goes wrong.

3 min