The Digestive System in 3D (IGCSE Biology 0610): Free Interactive Model of All 11 Organs

The digestive system is the topic everyone assumes they already know — right up to the moment an exam asks where bile is made versus where it is stored. So here is a free, interactive 3D digestive system for IGCSE Biology 0610: rotate the torso, tap any organ to learn exactly what it does, and hit "Test me" to find out which ones you only think you know. No sign-up, no download — it's live right here:

Drag to rotate · tap any organ · try "Test me". Works on phone, tablet and laptop. Want it bigger? Open the 3D digestive system on its own →

What are the organs of the digestive system?

For IGCSE Biology 0610 there are eleven, and the syllabus names them explicitly: mouth, salivary glands, oesophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine, rectum and anus. That is the list to learn — no more and no less. The appendix, caecum and epiglottis are not on this syllabus, so time spent on them earns nothing.

Worth noticing straight away: the food itself never enters the liver, gall bladder or pancreas. Those three are accessory organs that secrete into the gut rather than carry food along it. That is why the model above puts them off to one side, and why a diagram question will too.

Where does each part of digestion happen?

Small intestine or large intestine?

The single most useful sentence in this topic: the small intestine absorbs food, the large intestine absorbs water.

The small intestine has two halves that do different jobs — the duodenum completes digestion, and the ileum absorbs the digested molecules into the blood. It is also unusually long and lined with villi, giving an enormous surface area for that absorption. The large intestine takes what is left over, reclaims the water from it, and passes the solid remainder to the rectum for storage.

Digestion, absorption, assimilation, egestion — what's the difference?

These four words appear in the same questions and are marked strictly, so it is worth getting them exactly right:

• Digestion — breaking large insoluble food molecules into small soluble ones.
• Absorption — those small molecules passing into the blood, mostly through the small intestine.
• Assimilation — the body's cells taking them up and actually using them.
• Egestion — removing undigested food through the anus.

And the distinction examiners genuinely like to test: egestion is not excretion. Egestion removes material that was never absorbed into the body in the first place — it merely passed through. Excretion removes waste that the body itself made, such as carbon dioxide from respiration or urea from the liver.

Mechanical or chemical digestion?

Mechanical digestion breaks food into smaller pieces without changing what it is — the teeth chewing, the stomach churning. Chemical digestion changes the molecules themselves, using enzymes.

Bile is the one that causes arguments, and it is worth being precise: bile emulsifies fats, breaking large fat droplets into many small ones. That is a physical change, not a chemical one — no molecule is broken down. What it achieves is a much larger surface area for lipase to work on, which is why fat digestion is far faster with bile than without it. Bile also neutralises the acid arriving from the stomach, giving the enzymes of the small intestine the alkaline conditions they need.

Which enzyme is made where?

• Amylase — made in the salivary glands and the pancreas. Digests starch to maltose.
• Protease — made in the stomach and the pancreas. Digests protein to amino acids.
• Lipase — made in the pancreas. Digests fats to fatty acids and glycerol.

The pattern worth remembering is that the pancreas makes all three and delivers them all to the small intestine. And the reason stomach protease works in acid while pancreatic enzymes need alkaline conditions is simply that every enzyme has its own optimum pH — the same idea you met in enzymes, showing up again here.

What is peristalsis?

Waves of muscle contraction that push food along the gut. The circular muscle behind the ball of food contracts while the muscle in front of it relaxes, squeezing it onward — which is why swallowing works even if you are lying down or standing on your head. Food does not fall to your stomach; it is pushed.

Why rotating a 3D model beats memorising a diagram

A textbook diagram of the gut is a flat squiggle with eleven lines pointing at it, and it hides the thing that matters most: which organs the food actually travels through, and which ones simply feed into it from the side. Turn the model and that becomes obvious in seconds. Tapping an organ yourself and reading its job is active, and active beats passive every time — the idea behind all our interactive tools, with more on the evidence in our science-backed revision guide.

How to revise digestion properly

1. Tap all eleven organs
   Learn what each does and why. Note which three are not part of the tube — that is a favourite diagram question.
2. Follow one meal all the way through
   Say the route out loud from mouth to anus, naming what happens at each stop. Wherever you stall is your gap.
3. Separate the four "-ion" words
   Digestion, absorption, assimilation, egestion. Define each in one sentence without looking.
4. Prove it on a real question
   Finish on a past-paper question about digestion — see it, test it, then score it under exam conditions.

FAQ

Digestion looks like a list to memorise and is really a journey to follow. Rotate the model, trace one meal from mouth to anus, get the liver-and-gall-bladder pair straight, and keep the four "-ion" words apart. Do that and the topic is yours — most of the marks on it come from exactly those things.