Physical Digestion & The Tooth Factory
Breaking down food WITHOUT chemical change to increase surface area for enzymes
Physical Digestion Definition
The breakdown of food into smaller pieces WITHOUT chemical change. The goal is to increase surface area so enzymes have more space to attack.
Examiner Trap: Physical vs Chemical
Physical Digestion
- • Cutting with incisors
- • Tearing with canines
- • Grinding with molars
- • Churning in stomach muscles
- • NO new substances formed
Chemical Digestion
- • Uses enzymes
- • Breaks chemical bonds
- • Creates new molecules
- • Example: Starch → Glucose
- • Example: Protein → Amino acids
The Four Types of Teeth
Incisors
Cutting and biting food. Sharp, chisel-shaped edge at the front of the mouth.
Canines
Tearing food. Pointed teeth next to incisors, used for gripping and ripping.
Premolars
Crushing food. Flat surfaces with ridges behind canines.
Molars
Grinding food. Large, flat teeth at the back with multiple cusps.
Supplement: Bile's Role
Bile is produced in the liver and stored in the gallbladder. It performs TWO functions:
1. Emulsifies fats: Breaks large fat droplets into millions of tiny droplets (increases surface area for lipase enzyme)
2. Neutralizes stomach acid: Creates optimal pH for intestinal enzymes
⚠️ EXAMINER TRAP: Bile does NOT chemically digest fats. It only makes them smaller (physical process).
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