Physical Digestion

Summary

Physical digestion involves breaking down food into smaller pieces without changing the chemical structure of the food molecules. It increases the surface area of food for enzyme action in chemical digestion.

• Incisors — sharp-edged teeth used for cutting food.
  Example: Biting into an apple.
• Canines — pointed teeth used for tearing food.
  Example: Tearing meat.
• Premolars — flat-topped teeth used for grinding food.
  Example: Chewing bread.
• Molars — larger flat-topped teeth used for grinding food.
  Example: Crushing nuts.
• Enamel — the hard outer layer of the tooth.
  Example: Protects the tooth from decay.
• Dentine — the layer beneath the enamel, making up most of the tooth.
  Example: Supports the enamel.
• Pulp Cavity — the innermost part of the tooth containing nerves and blood vessels.
  Example: Provides nutrients and sensation.
• Bile — a digestive fluid that emulsifies fats.
  Example: Breaks down large fat droplets into smaller ones for easier digestion.

Exam Tips

Key Definitions to Remember

• Physical digestion: Breakdown of food into smaller pieces without chemical change.
• Emulsification: Process of breaking down large fat droplets into smaller ones.

Common Confusions

• Confusing physical digestion with chemical digestion.
• Thinking emulsification is a chemical change.

Typical Exam Questions

• What is the role of incisors in digestion?
  Incisors are used for cutting food.
• How does bile aid in digestion?
  Bile emulsifies fats, increasing their surface area for enzyme action.
• What is the function of the pulp cavity in a tooth?
  It contains nerves and blood vessels, providing nutrients and sensation.

What Examiners Usually Test

• Understanding the difference between physical and chemical digestion.
• Identifying the functions of different types of teeth.
• Explaining the role of bile in digestion.