Stage 1 - Mouth
- Digestion starts with the mechanical digestion by the teeth in the mouth.
- Then a chemical digestion by saliva starts - carbohydrase digests glusoce
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Step 2 - Oesophagus
- This is a muscular tube (gullet).
- When you swallow, the food moves to the stomach.
- The food moves by involentary contractions (peristalsis).
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Step 3. - Pancreas & Stomach
- pH of 2-3
- The pancrease will secrete enzymes - lipase, protease & carbohydrase.
- The stomach will secrete hydrochloric acid that will digest bacteria.
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Step 4. - Small Intestine
- The rest of the enzyme carbohydrase will digest starch into glucose.
- Protease will digest protein to amino acids.
- Lipase will digest fats into fatty acids & glycerol.
- The food molecules have to be small enough to be absorbed throught the wall of the small intestine & into the blood.
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Step 5. - Large Instestine
- The water is reabsorbed into the blood.
- Fibre is insoluble & cannot be digested, this is why it is stored & then egested through the anus.
egested - pushed out
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Bile & Liver
- Liver produces bile (chemical).
- Bile is stored in the gall bladder
- Bile has 2 functions - neutralise stomach acid & produce alkaline conditions for enzymes to work in
- Emulisification converts large fat globules to smaller fat droplets
- The enzymes produced by the body help digestion.
- Everything that is digested is absorbed into the blood.
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