1. The Digestive System
3.5 & 3.6

2. Image from: http://www. webmd

3. Stages of Food Processing
ingestion
digestion
absorption
egestion

4. Ingestion teeth: physical breakdown of food
salivary glands: amylase in saliva breaks down starch (chemical digestion)
tongue: forms bolus, pushes it back to pharynx
esophagus: peristalsis moves bolus down

5. Digestion (Stomach)
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6. Digestion (Stomach)
gastric juices: hydrochloric acid + enzymes (e.g., pepsin)
mucus: protects lining of stomach from damage
chyme = partly digested food, water, and gastric juice that enters the small intestine

7. Digestion (Duodenum)
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8. Image from: http://www. shadygroveadventisthospital

9. Digestion (Duodenum)
bile (produced in liver, stored in gall bladder): emulsifies fat
lipase, amylase, trypsin (produced in pancreas): digest fat, starch, protein
maltase, peptidases (produced in duodenum): digest maltose, polypeptides

10. Absorption (Small Intestine)
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11. Small Intestine
up to 7 metres in length (25 cm of which is duodenum), 2.5 cm wide
villi & microvilli increase surface area for absorption
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12. Large Intestine 1.5 metres long, 5 cm in diameter absorbs water
helpful bacteria produces vitamins K and B
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13. Egestion
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14. Animations Process of digestion:
Animation & Quiz:

15. Is it Art?
Artist Wim Delvoye