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

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

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.

9. Regions of Alimentary Canal FunctionsRelations to : ingestion/ Digestion/ Absorption/ Assimilation Mouth (more on chewing/teeth structure/ fluoride for teeth) Use of lips / teeth / tongue to break down food mechanically (Mastication = chewing). Taste buds decide chemically if safe to eat or not. Ingestion Salivary glandsWater + Amylase (starch -> maltose) + Mucus (slippery substance that allows slide) Digestion EsophagusTakes food from mouth to stomach after swallowing.Ingestion StomachGastric juices (HCl (pH 2) + pepsin – to break down protein) secreted & Mucus also secreted to protect the stomach from being digested itself (but if it does happen – the sore is called an Ulcer. Physical churning is called Peristalsis. *Vitamins are directly absorbed Digestion *Absorption

10. Regions of Alimentary Canal FunctionsRelations to : ingestion/ Digestion/ Absorption/ Assimilation SI :DuodenumLiver / Pancreatic juices mix here. * Contains Villi (finger like projections) Digestion * Absorption SI : IleumContains villi: (finishes digestion / absorption)/ increases surface area to seep up the rate of absorption) / thin walls so not must time / space for absorption. All large molecules broken down to their simplest parts (maltose -> glucose via maltase) Absorption: sugar / a. a. / fatty acids / glycerol / vitamins / inorganic ions / water (into blood or lymph) PancreasReleases Pancreatic juices (enzymes) & flows into duodenum via pancreatic duct. Also contains Sodium hydrogen carbonate (helps neutralize acids) from stomach pH 2 -> pH 6.5. =. Avoids harm to small intestine. Enzymes = carbohydrase (amylase) & Protease (trypsin) & Lipase Digestion SI : Small Intestine / LI = Large Intestine

11. Regions of Aliment ary Canal FunctionsRelations to : ingestion/ Digestion/ Absorption/ Assimilation liverProduces bile / store in gal bladder After absorption of molecules – all go to the liver via hipatic portal vein. Liver’s job ; to Sort out molecules: Some molecules will be carried in blood to the cells that need them. Some will be stored in liver Some will be changed for storage Eg. Glucose that is not used will be converted to glycogen (stored in liver). Long term stored glycogen will be converted to fat (stored in other areas eg. Abdomen). Eg. Amino acids will be used to make protein and then transported by blood to other parts of the body. Excess a. a. will be converted into urea and removed via urine. Break down dangerous toxins (alcohol) Liver disease = cirrhosis Assimilation

12. Regions of Alimentary Canal FunctionsRelations to : ingestion/ Digestion/ Absorption/ Assimilation Gal BladderBile is stored here and released into the duodenum when food is there via the bile duct. Bile = Helps digest fats (made of bile salts). Bile Salts break fat into droplets this is called Emulsification. It makes it easier for the fats to be digested and later absorbed. Digestion LI: ColonFiber and water left. Water is absorbed 5-10 decimeter cubed of water absorbed by the SI 0.3-0.5 Decimeter cubed by the LI Absorption LI: RectumStores fecesEgestion AnusRemoves fecesEgestion 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 StructureFunction IncisorsIn front of mouth – helps to bite off pieces of food to take into the mouth caninesNext to incisors. Same function as incisors. In other carnivores – they are longer – for killing prey Pre molarsBehind the canines- for chewing food into small pieces and mix with saliva – easier for swallowing and tasting & Increase surface area of food so that digestive enzymes can work on food. molarsBehind pre molars. Function – same as pre molars.

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