PP 1 Human Alimentary Canal/ Mechanical Digestion

1. PP 1 Human Alimentary Canal/ Mechanical Digestion Plus –Definitions for All of Digestion

2. Definitions • Ingestion – taking in substances (food [eating] / drinking) into the body through the mouth. • Digestion – breaking down large insoluble food molecules into small water soluble molecules using mechanical and chemical processes. • Absorption – movement of digested food molecules through the wall of the intestines into the blood or lymph .

3. Definitions continued Assimilation – movement of digested food molecules into the cells of the body where they are used – becoming part of cell. Egestion – Passing out of food that has not been digested as faeces through anus

4. Alimentary canal = long tube that starts at the mouth and ends at the anus – the way food travels through the system. Ingestion Assimilation ENZYMES ENZYMES Egestion Absorption Digestion

5. Nasal Cavity Mouth Trachea Small intestine = Duodenum -> Ileum Oesophagus Liver Stomach Large Intestine = Colon -> Rectum Gall Bladder Pancreas Duodenum Ileum Large Intestine Colon Abdomen = the area below Ribs and above Hip bone Rectum Appendix Anus

7. Capillary absorb: • sugar / a. a. / vitamins / inorganic ions / water • Lacteal absorb: • fatty acids / glycerol • The Villi: Surface area is important

8. Breaking food down • 10 hours for food to pass through from the mouth • Mechanical digestion = physical breaking up food by teeth (chewing) and stomach walls churning (Peristalsis). • Chemical Digestion = Break down of food molecules via enzymes.

10. SI : Small Intestine / LI = Large Intestine

12. SI : Small Intestine / LI = Large Intestine

13. Process of Chewing • In the mouth: • Large premolars and molars • Both have broad surfaces / ridges on them => when pushed together they crush the food • To increase the surface area of the food • Makes it easier for the enzyme to work on the food. • Bolus = Food made by the tongue into a ball of food to be swallowed.

14. Human teeth – structure / function

15. Dental decay / proper teeth care • Tooth decay – when enamel erodes due to acids (produced by bacteria) • Plaque formation – bacteria and food caught in between teeth that harden around the tooth. • Foods full of sugar can increases changes for plaque formation => dissolve enamel down to the dentine.

16. Teeth decay prevention • Avoid sugary foods. • Regularly clean your teeth (brush / dental floss/ tooth pick) • Use tooth paste with fluoride (is absorbed by the teeth and prevents acid build up) • Visit dentist regularly.

17. Fluoride & prevention of tooth decay • Fluoride in drinking water creates less tooth decay. • Too much fluoride can cause black spots of teeth. Can cause vomiting / stomach cramps too. • Best concentration of fluoride is 1 part per million.

18. Peristalsis • Longitudinal muscles – lengthwise • Circular muscles – around Swallow -> circular muscle relaxes (tube gets wider) -> behind food circular muscle contracts . When circular muscle relaxes – longitudinal muscle contracts (visa versa) • Happens all the way down the alimentary canal