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the digestive system
LC Biology
| Term | Definition |
|---|---|
| ingestion | food is taken into the alimentary canal |
| digestion | food is broken down into smaller soluble pieces |
| absorption | the movement of digested food from the alimentary canal into the blood system |
| egestion | Removal of unabsorbed material as faeces |
| mechanical breakdown of food involves | 1) teeth 2)contractions in stomach wall 3)peristalsis |
| peristalsis | Rhythmic muscular contraction and relaxation in the wall of the alimentary canal causing the food to move along the canal |
| incisors | job=cutting |
| canines | job= tearing |
| Pre Molars and Molars | job=crushing and grinding |
| Human dental formula | 2(i2/2 C1/1 Pm 2/2 M 3/3) |
| oesophagus | -connects pharynx to stomach -food moves down the this by peristalsis |
| stomach | stores food for four hours |
| Chyme | mixture of food and gastric juices formed in the stomach |
| functions of gastric juice | -mucus -HCL -Pepsin |
| mucus | function= lines and protects the stomach wall |
| HCL | function= kills bacteria in food and activates pepsinogen |
| pepsinogen | HCL coverts this to the active enzyme. this enzyme digets protein |
| small intestines parts | duodenum jejunum ileum |
| duodenum | function- most digestion takes place here |