The document summarizes the human digestive system. It describes the stages of ingestion, digestion, absorption, assimilation, and egestion. Key parts of the digestive system discussed include the mouth, stomach, small intestine, large intestine, liver, and pancreas. The roles of enzymes and absorption through the small intestine walls are also summarized.

1. HUMAN NUTRITIONDIGESTIVE SYSTEM

2. THE ALIMENTARY CANALINGESTION: takingsubstances (e.g.food, drink) intothebodythroughthemouth.DIGESTION: the break-down of large, insoluble foodmoleculesintosmall, water-soluble moleculesusingmechanical and chemicalprocesses.ABSORPTION:themovement of digestivefoodmoleculesthroughthewall of theintestineintothebloodorlymph.ASSIMILATION: themovement of digestivefoodmoleculesintothecells of thebodywherethey are used, becomingpart of thecells.EGESTION: the ´passingout of foodthat has notbeendigeste, as faeces, throughtheanus.

4. Namethelayers of tissuethatmake up thealimentary canal, startingfromtheinside

5. PERISTALSISA contraction in oneregion of thealimentary canal isfollowedbyanothercontractionjustbelowit so that a wave of contractionpassesalongthe canal pushingfood in front of it.

6. DIGESTION:Physical:teethChemical: enzymes

8. Chemicaldigestion

9. MOUTH -Ingestion -DigestionFoodischewed and mixedwithsaliva.

13. Howto reduce therisk of toothdecay-Eatingfoodwith a lowsugarcontent. Regular and effectivebrushing of teeth at leasttwice a daytopreventthebuild up of plaque.- Use a fluoridetoothpasteregularly. Itmakesyourteeth more resistanttodecay

14. Chemicaldigestion(mouth)Saliva: containssalivaryamylasestarch -> maltose

15. SWALLOWINGEnsuresthatfooddoesnotenterthewindpipe (trachea) and cause choking.Beginning: voluntaryThen: involuntary

17. STOMACH

18. STOMACHFunctions: - storesfoodfrom a meal. - turnsfoodinto a liquid (peristalticmovements) - releasesfood in smallquantities at a time totherest of thealimentary canal (pyloricsphincter)

19. Chemicaldigestion:Production of gastricjuice(glands in thelining) - Enzyme: pepsin (protease)Proteins -> peptides- Hydrochloricacid: providesthebestdegree of acidityforpepsintowork in and killsmany bacteria of food.

20. THE SMALL INTESTINEDuodenumIleumChemicaldigestionEnzymesfrom:PancreaticjuicesBileIntestinal juices

21. Liver, gallbladder, duodenum and pancreas

22. PANCREASSecretion of pancreaticjuice:deliveredtotheduodenumbythepancreaticduct. i) Enzymes:-Proteases:Proteins -> peptides -> aa- Pancreaticamylase:Starch -> maltose- Lipase:Fats -> fattyacids + glycerolii) Sodiumhydrogencarbonate: neutralizestheacidliquidfromthestomach so thatpancreaticenzymesworkcorrectly. (alkalineconditions)

23. BILEProducedbytheliver.Stored in thegallbladder.Deliveredtotheduodenumbythebileduct.No enzymesBilepigment:fromthe break down of haemoglobin in theliver.Bilesalts: Emulsifythefats: they break them up intosmalldropswhich are more easilydigestedbylipase.

24. INTESTINAL JUICESTheepithelialcells of thevilli produce enzymeswhichcompletethebreakdown of: - Maltose - Peptidesbeforethey are absorbed.Maltose -> glucosePeptides -> aa

25. FINAL PRODUCTS OF DIGESTION

27. ABSORPTION: ILEUM

28. VILLI: Hystology

29. Structure of a villus

30. MoleculesEpithelialcells -> a largeproportion of ↓ fattyacid + glycerolcapillaries (bloodstream ) ↓ ↓ formfatsagainveinsveins ↓ ↓ passtolactealsHepatic Portal Vein↓ ↓ lymphaticsystemLIVER↓General circulation (vena cava)

31. LARGE INTESTINEColon and rectumMaterial thatreachesitcontains:i) waterwithundigestedmatterii) celluloseiii) fibre: digestedpartlyby bacteriaiv) mucus v) deadcellsfromthelining of thealimentary canalFunction: absorption of water.semisolidwaste -> faeces -> rectum -> anus (EGESTION)

32. ASSIMILATIONGlucoseRespirationenergyFats -Are builtintocellmembranes and othercellstructures - Source of energyAmino acids - Built up intoproteins. Functions??

33. STORAGE OF DIGESTED FOODGlucose - Changed in thelivertoglycogen - Some of theglycogenisstored in liver (short- termstore) and muscles.- LIVER: If ↓ bloodsugarsGlycogen -> glucose -> circulation - MUSCLES: glucose: for muscular activity - Excess of glucose: convertedtofat and stored in fatsdepots

34. STORAGE OF DIGESTED FOODFats - Thereis no limittostorage of fats - Long- termstore as fatdepots in:-abdomen - round thekidneys (adiposetissue) - undertheskin

35. STORAGE OF DIGESTED FOODAmino acids - They are notstored in thebody - Thosenotused in proteinformation are deaminated(in theliver)

36. LIVERFunctionsRegulation of bloodsugars.Production of bile.DeaminationStorage of iron.Manufacture of plasma proteins.Detoxication.Storage of vitamins