PancreasClear

How does the pancreas work?
Behind your stomach sits a soft, 15 cm organ that does two jobs at once: it pours out a litre or more of digestive juice a day, and a million tiny islands inside it keep your blood sugar steady with insulin. Take it apart in 3D, watch a beta cell taste sugar, and see what goes wrong in diabetes.

▶ Play with it  ·  Read the 60-second explainer  ·  Watch the 40-second video

In 60 seconds

1. Two organs in one. The pancreas lies behind the stomach, about 15 cm long and 80 g, with its head in the C of the duodenum and its tail at the spleen. About 98% of it makes digestive juice; about a million islets of Langerhans, just 1 to 2% of it, make hormones such as insulin.
2. A juice factory with a safety lock. Acinar cells make amylase, lipase and protein-cutting enzymes, about 1 to 1.5 litres of juice a day. Trypsin is made switched off and only switched on in the gut by enteropeptidase, so the pancreas does not digest itself. Duct cells add bicarbonate to neutralise stomach acid, on cue from the hormones secretin and CCK.
3. A cell that tastes sugar. Beta cells burn glucose to make ATP. ATP shuts potassium channels, the cell's voltage rises, calcium rushes in, and insulin granules release. More sugar means more insulin. Alpha cells do the opposite job with glucagon.
4. A thermostat for blood sugar. Insulin lets muscle and fat take in glucose and tells the liver to store it; glucagon tells the liver to release it. Together they keep blood glucose around 70 to 100 mg/dL before breakfast and usually below about 140 after meals, though the whole bloodstream holds only about a teaspoon of sugar.
5. When the thermostat breaks. In type 1 diabetes the immune system destroys the beta cells. In type 2, the most common kind, cells resist insulin and beta cells slowly fall behind. HbA1c shows average glucose over about three months. About 589 million adults worldwide, and an estimated 101 million people in India, live with diabetes. Only doctors diagnose it.
6. Keeping it healthy. Pancreatitis happens when enzymes switch on inside the gland, most often after gallstones or heavy alcohol use, and needs urgent care. Pancreatic cancer is hard to find early. Studies in the USA and India found that lifestyle programmes lowered the chance of type 2 in people with raised glucose. For your own health, talk to a doctor.

Words worth knowing

Term	Meaning
Exocrine and endocrine	Exocrine glands send their product down ducts, like digestive juice; endocrine glands release hormones into the blood, like insulin.
Acinus	A grape-like cluster of enzyme-making cells around a tiny central channel.
Zymogen	An enzyme made switched off, such as trypsinogen, so it cannot do damage until it reaches the gut.
Secretin and CCK	Hormones from the duodenum that tell the pancreas to send bicarbonate and enzymes when food arrives.
Islet of Langerhans	A tiny cluster of hormone-making cells; about a million are scattered through the pancreas.
Insulin	The hormone from beta cells that lets cells take in glucose and tells the liver to store it.
Glucagon	The hormone from alpha cells that tells the liver to release glucose when blood sugar falls.
Insulin resistance	When cells respond less to insulin, so more is needed to do the same job; central to type 2 diabetes.
HbA1c	A blood test showing how much haemoglobin has glucose attached, a guide to average glucose over about three months.

A short history

2,500 years from 'honey urine' in ancient India to sensors that talk to insulin pumps.

• 500 BCE · Madhumeha: 'honey urine' (Sushruta and Charaka (texts attributed to them), Ancient India)
• 300 BCE · The pancreas is first described (Herophilus of Chalcedon, Alexandria, Egypt)
• 1674 · Urine 'wonderfully sweet' (Thomas Willis, London and Oxford, England)
• 1869 · Islands in the pancreas (Paul Langerhans, Berlin, Germany)
• 1889 · No pancreas, then diabetes (Oskar Minkowski and Joseph von Mering, Strasbourg (then Germany, now France))
• 1902 · The first hormone: secretin (William Bayliss and Ernest Starling, University College London, England)
• 1922 · Leonard Thompson gets insulin (Leonard Thompson, treated by the Toronto team, Toronto General Hospital, Canada)
• 1923 · A Nobel Prize, and a patent for $1 (Banting, Macleod, Best and Collip, Stockholm, Sweden, and Toronto, Canada)

The full story, with 28 moments, charts, people and 38 sources: glassbox.how/e/pancreasclear/history. The data lives in history.json.

Video and slides

Made with the Glassbox studio from this box's storyboard (window.glassbox.director). Free to reuse under CC BY 4.0.

File	What	Size
glassbox/reel.mp4	Reel / Short, with captions and soundtrack	1080×1920
glassbox/video.mp4	YouTube video, with captions and soundtrack	1920×1080
glassbox/slide-1…10.jpg	Instagram carousel	1080×1350
glassbox/thumb.jpg	YouTube thumbnail	1280×720
glassbox/cover.jpg	Share card and repo social preview	1200×630
glassbox/history-reel.mp4	“History in 10 moments” Reel / Short	1080×1920
glassbox/history-slide-*.jpg	History carousel	1080×1350
glassbox/post.json	Post copy and schedule used by the publish kit

Privacy

This box has no accounts and no ads, and it ships its own fonts and libraries. When you run it yourself it sends nothing anywhere. On glassbox.how, the site's /bar.js also loads Glassbox's analytics: Google Analytics to count visits (it asks first in the EU, UK and Switzerland, and stays off when your browser sends Global Privacy Control or Do Not Track) and ClickTrust to detect bots.

It remembers a few things in your own browser only, and never sends them anywhere:

Browser storage key	What it holds
pancreasclear.v1	Which chapters you have opened, your best quiz scores, and sound on or off.

Exactly what each one sees is at glassbox.how/privacy.

Licences

• Code: MIT. Use it, change it, ship it.
• Explanations, text, images and videos (glassbox.json, glassbox/): CC BY 4.0. Credit “Glassbox, glassbox.how/e/pancreasclear”.
• Third-party parts keep their own licences: three.js (MIT), Geist, Instrument Serif (SIL OFL 1.1).
• The Glassbox name and logo aren't covered by either licence. See the terms.

Found a mistake? Open an issue. Corrections happen in public.

Run it

It's plain HTML, CSS and JavaScript. No build step and no dependencies. Run locally, it contacts no other website.

python3 -m http.server 8000

Three.js and the fonts ship in vendor/ and fonts/, so it also works offline.

Then open http://localhost:8000.

How it's built

File	What
index.html, css/app.css	The page and its styles
js/app.js, js/stage.js, js/ui.js, js/kit.js	The shared Glassbox 3D engine: chapters, 3D stage, controls, quiz, video director
js/chapters/*.js	One file per chapter: the 3D model, controls, text, key terms, quiz and video scenes
js/pancreas.js	Shared 3D models: the pancreas with its ducts, vessels and neighbours, an islet of Langerhans, the glucose chart, labels
js/glucose.js, js/body.js	The blood-glucose day model (typical, type 1, type 2; sources in the file) and the stylised body loop it drives
glassbox.json	Title, question, explainer beats, key terms, browser storage and credits shown on glassbox.how
reel in each chapter	The storyboard the Glassbox studio records into short videos
glassbox/	The published video, slides, thumbnail and post copy
fonts/, vendor/three/	Self-hosted Geist and Instrument Serif (SIL OFL 1.1) and three.js (MIT)