Digestion & Enzymes

Activities to try

1. 1

   Follow your food: pilot a meal through the gut

   Why it works: Digestion is an ordered process that physically and chemically breaks food down; big insoluble molecules cannot be absorbed until enzymes cut them into small soluble ones. Physical breakdown (and bile) increases surface area so enzymes work faster.

   1. Drive a mouthful of food step by step along the tract: mouth → oesophagus → stomach → small intestine → large intestine.
   2. At the mouth, trigger both actions: teeth chew (physical) AND saliva's starch enzyme (amylase) begins cutting starch (chemical).
   3. In the stomach, trigger churning plus acid, and a protein-cutting enzyme (protease) starting to break down protein.
   4. In the small intestine, release bile — made by the liver (stored in the gallbladder) — to break a fat blob into small droplets (physical, increasing surface area), then let enzymes from the pancreas and small intestine finish cutting molecules small.
   5. Watch the now-tiny molecules cross the villi into the blood; see water reclaimed in the large intestine.
2. 2

   Name the tract: tappable labelled digestive system

   Why it works: Each organ has a named role in sequence, including the liver (bile) and pancreas (enzymes); absorption happens mainly in the small intestine, not the stomach.

   1. Tap each organ along the tract and read its job: mouth (chewing + salivary amylase), oesophagus (carries food down), stomach → 'muscular bag; acid + protease begin protein digestion', liver → 'makes bile that emulsifies fat', pancreas → 'makes digestive enzymes', small intestine → 'enzymes finish digestion; small soluble molecules absorbed here', large intestine → 'reabsorbs water'.
   2. Match each organ to its function and each key enzyme to where it is produced (salivary glands, stomach, pancreas/small intestine).
   3. Use a lift-the-flap check: 'Does the stomach do most absorption?' → reveal 'No — the small intestine does.'
3. 3

   The cracker that turns sweet: tasting enzyme action (predict–observe–explain)

   Why it works: Chemical digestion by an enzyme is a real, directly experienced event — not just breaking food into smaller pieces. Enzymes are catalysts, not living creatures.

   1. Before chewing anything, PREDICT how the taste of a plain cream cracker will change if you chew it slowly and hold it in your mouth for a minute or two, and say why.
   2. After allergy/food-safety checks, chew a plain cream cracker slowly and hold it in the mouth for a minute or two, paying attention to any change in taste.
   3. Observe and record what you actually taste: many people notice a slight sweetness developing as salivary amylase breaks starch into sugars such as maltose, though how strong the effect is varies from person to person.
   4. Explain what happened, distinguishing what teeth do (break into pieces) from what the enzyme does (cut molecules).
   5. Discuss the probe questions: Why can't a tiny bread crumb pass straight into the blood as it is? What is the difference between what your teeth do and what an enzyme does? If enzymes aren't alive, how do they break food down? Where along the gut does most digested food cross into the blood, and why there?