7.3 Physical Digestion

• Physical digestion is the breakdown of food into smaller pieces without chemical change to the food molecules
• It increases the surface area of food for the action of enzymes in chemical digestion

Teeth

Tooth diagrams are on the way 🙂

• Incisors → Chisel-shaped for biting and tearing
• Canines → Pointed for tearing and piercing
• Premolars and molars → Large surface area with uneven ‘cusps’ for grinding and chewing
  
• Each tooth is embedded in bone and gum

The Stomach

• Physical digestion
• Muscles lining the stomach contract to churn the good with gastric juice

The role of bile

• Emulsifies fats and oils to increase surface area for chemical digestion
• Bile is alkaline to neutralise acidic hydrochloric acid from the stomach
  
• IMPORTANT! Emulsification is considered physical not chemical digestion, there is no chemical change