Through the Intestines

Six parts following a meal through seven metres of tube. The small intestine is where almost all absorption happens, and the problem it solves is surface area: it opens with the organ whole, then the duodenum where bile and pancreatic juice arrive, then a zoom into the villi — folds upon folds upon folds — that turn a narrow tube into a surface the size of a room. The fourth part is the movement itself, which is not a simple push but a squeezing that mixes as much as it moves. Then the large intestine, whose job is water rather than food, and finally the rectum, where the body holds the result until it is convenient.

45 min to complete
Beginner level
6 Parts

CodePLU Goal

Upgrading Human Mental Models

Learn how to think in Workflows

The place where the goodness in your food is actually absorbed is a coiled tube seven metres long, folded and packed to squeeze the most out of every meal
Beginner 7 min Part 1

Why Is Your Small Intestine So Long and Folded?

The small intestine is where nutrients are absorbed — and everything about it is built to maximise that. Label the coils, circular folds, lumen and wall, and learn why the small intestine is so long, so coiled and so folded — in an interactive playground.

The short, C-shaped first stretch of your small intestine is where the stomach's acid meets the juices of the liver and pancreas — the busiest crossroads in your digestion
Beginner 7 min Part 2

What Is the Duodenum, the Gut's Mixing Bowl?

The duodenum is the C-shaped first part of the small intestine, where stomach acid is neutralised and bile and pancreatic juice go to work. Label the duodenum, its upper end, inner folds, wall and lower end, and learn why this short stretch is digestion's busiest crossroads — in an interactive playground.

Zoom right into the lining of the small intestine and meet the tiny fingers — the villi — where a digested meal finally crosses out of the gut and into your body
Beginner 8 min Part 3

How Does Your Gut Absorb Food Into Your Blood?

The small intestine's lining is carpeted with tiny fingers called villi, where nutrients finally cross into the body. Label the microvilli, absorptive cells, lacteal, blood capillaries and goblet cell, and see how a digested meal is absorbed — in an interactive playground.

Your gut does not just push food along — it also churns it in place, pinching it into pockets and sloshing it back and forth so every drop meets the juices and the absorbing wall
Beginner 7 min Part 4

How Does Your Intestine Mix Your Food?

The intestine mixes food with a movement called segmentation — pinching it into pockets and churning it in place. Label the intestine wall, a constriction, a relaxed section and the chyme, and see how the gut mixes a meal rather than just pushing it along — in an interactive playground.

The colon frames your belly like a giant question mark — reclaiming water from the leftovers, forming your waste, and housing trillions of helpful bacteria along the way
Beginner 8 min Part 5

What Are the Parts of Your Large Intestine?

The large intestine, or colon, is the final stretch of the gut — it absorbs water and forms waste. Label the cecum, appendix, ascending, transverse, descending and sigmoid colon, and follow the leftovers around its path — in an interactive playground.

The very end of your gut is a storage chamber with two locks — one automatic, one you control — which is the whole reason you can wait until you reach a toilet
Beginner 8 min Part 6

How Does Your Body Hold and Release Waste?

The rectum stores waste, and two sphincter muscles decide when it leaves. Label the rectum, rectal wall, anal columns, anal canal and sphincter muscle, and learn how your body holds and releases waste — in an interactive playground.