📖 Notes LESSON 10 OF 16

Digestive System — Gut to Cells

⏱️ 25 min
🍽️ Human Physiology

From Mouth to Absorption

Every enzyme in digestion has one job and one location. Matching enzyme to substrate to product is exactly what MDCAT digestive questions test.

Mouth → ... → Anus

1
Mouth
Amylase begins breaking down starch into maltose.
2
Stomach
Gastric juice (HCl + pepsinogen) creates pH 2; pepsin breaks proteins into peptides.
3
Small Intestine (ileum)
Villi and microvilli create a huge surface area; glucose, amino acids, and fatty acids are absorbed.
4
Large Intestine
Water reabsorption and gut bacteria activity.

Enzyme → Substrate → Product

🧪 Digestive Enzymes at a Glance
Amylase
Starch → Maltose
Mouth
Pepsin
Protein → Peptides
Stomach
Lipase
Fats → Fatty acids + glycerol
S. Intestine
Lactase
Lactose → Glucose + Galactose
S. Intestine
💡
Exam tip
MDCAT often gives an enzyme name and asks for its substrate/product, or vice versa — memorising the four enzyme rows above as complete triples (not isolated facts) covers the majority of these questions.
🗒 Cheat Sheet 📝 Worksheet