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Topic Notes · Easy summaries with diagrams
Chapter 1 — Chapter 1 — Human Digestive System
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📘Easy summary
Digestion begins in the oral cavity: teeth cut and grind food (mechanical digestion); the tongue mixes it with saliva and rolls it into a bolus. Three pairs of salivary glands secrete saliva containing water and mucus (moisten, lubricate) and salivary amylase, which starts digesting starch into maltose. Swallowing pushes the bolus into the pharynx; the epiglottis closes the windpipe. The oesophagus carries food to the stomach by peristalsis — wave-like contractions and relaxations of its muscles. No chemical digestion occurs in the oesophagus.
⭐Key points
- Saliva: amylase + mucus + water.
- Peristalsis occurs throughout the alimentary canal.
🔬Diagram
🌿Real-life example
Chewing bread for long makes it taste sweet as starch becomes maltose.
💡Exam tip
- Distinguish mechanical and chemical digestion.
✅Quick check
1. Starch digestion begins in:
2. No chemical digestion in:
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