CIE IGCSE Biology: 复习笔记：7.1.4 Teeth & Digestion

• Mechanical digestion is the breakdown of food into smaller pieces without chemical change to the food molecules
• It is mainly carried out by the chewing action of the teeth, the churning action of the stomach and the emulsification of fats by bile in the duodenum
• Teeth are held firmly in the bone of the jaw
  • They are used for chewing to increase the surface area of the food so that it can be exposed to saliva and other digestive juices and broken down more quickly
• The differing shapes and sizes of teeth enable them to perform slightly different functions:
  • Incisors - chisel-shaped for biting and cutting
  • Canines - pointed for tearing, holding and biting
  • Premolars and molars - larger, flat surfaces with ridges at the edges for chewing and grinding up food

Types of teeth

Structure of a typical tooth

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