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1、Main processes of mammalian nutritionzIngestion zDigestion zAbsorptionzAssimilationzEgestionDigestionAbsorptionEgestionNextNextBackBackMain processes of mammalian nutritionzIngestion zDigestion zAbsorptionzAssimilationzEgestionDigestionAbsorptionEgestionNextNextBackBackIngestion zis the intake of fo
2、od into the alimentary canalzrelevant organs:yteethzrelevant processes:yswallowingyperistalsisNextNextBackBackIngestion II zis the intake of food into the alimentary canalzrelevant organs:yteethzrelevant processes:yswallowingyperistalsisBackBackNextNextincisorcaninepremolarmolarDigestionzis the brea
3、king down of food into molecules small enough to be absorbed into the bodyzrelevant organsymouth and teethyalimentary canalystomachyduodenumBackBackNextNextAbsorptionzis the movement of digested, soluble and simple molecules from the gut through the wall into the body (Contd)zrelevant processesydiff
4、usionyactive transportzrelevant structuresBackBackNextNextAssimilationzis the uptake & utilisation of absorbed food molecules by all body cellszfate of the absorbed foodyglucose energy productionyamino acids building up body materials yfats energy reservezroles of liver in assimilationBackBackNextNe
5、xtEgestionzis the removal of undigested and unwanted food materials from the alimentary canalzrelevant structureszabnormal cases:ydiarrhoea yconstipationBackBackNextNextEgestion IIzis the removal of undigested and unwanted food materials from the alimentary canalzrelevant structureszabnormal cases:y
6、diarrhoea yconstipationNextNextBackBackTeethzstructure of a toothyenamelydentineypulp cavityztypezdentitionNextNextBackBackEnamelDentinePulp CavityJaw BoneCementNerve & blood vesselCrownNeckRootTeeth IIzstructure of a toothyenamelydentineypulp cavityztypezdentitionCrownNeckRootEnamelDentinePulp Cavi
7、tyJaw BoneCementNerve & blood vesselNextNextBackBackEnamelzoutermostznon-livingzhardest layerzmade up of ycalcium phosphateycalcium fluoride yorganic matterNextNextBackBackDentinezmiddle layerzhard, bone like (softer than enamel)NextNextBackBackPulp Cavityzinnermost layerzliving cells, blood vessels
8、 and nervezblood vessels: oxygen and nutrientznerves: sensitive to stimuli ytemperatureypressureNextNextBackBackType of TeethNextNextBackBackDentitionzdental formula of a humanytype of teeth yon one side onlyyupper jawylower jawymilk teeth: permanent teeth: 21202120212021202123212321232123NextNextBa
9、ckBack2032premolarmolarcanineincisorTooth Decayzcaused by the chemical actions of bacteria in plaquezplaque is a sticky, invisible film on the teeth surfacezbacteria turns sugars into acidszacids dissolve the enamel and dentineNextNextBackBackTooth Decayzcaused by the chemical actions of bacteria in
10、 plaquezplaque is a sticky, invisible film on the teeth surfacezbacteria turns sugars into acidszacids dissolve the enamel and dentinezirritation on the nerve, cause toothacheNextNextBackBackHow to prevent tooth decayzgood brushing habitszusing appropriate cleaning materialszavoiding sugary foodzhav
11、ing a balanced dietzhaving regular dental check-upNextNextBackBackAlimentary Canalza tube from mouth to anuszis modified into different structureszdigestive system = alimentary canal + associatedalimentary canalalimentary canalassociated glandsassociated glandsNextNextBackBackAlimentary Canalza tube
12、 from mouth to anuszis modified into different structureszdigestive system = alimentary canal + associated glandszsequence of the structuresoesophagusstomachduodenumileumcaecumappendixcolonrectumanusSalivary glandGastric glandPancreasLiverIntestinal glandNextNextBackBackalimentary canalalimentary ca
13、nalassociated glandsassociated glandsSwallowingztongue raises pushing the bolus to the backzbolus pushes the soft palate upwardszepiglottis lowers and covers the tracheazbolus enters the oesophagusNextNextBackBackPeristalsiszfood is moved along the canal byzrhythmic contraction and relaxation of two
14、 musclesycircular muscleylongitudinal musclezdemonstrationPeristalsisNextNextBackBackOesophagusDigestion IIzonly small molecules can pass through the wall of intestinezfood are usually composed of large moleculeszfood should be digested before absorptionzphysical methodszchemical methodsNextNextBack
15、BackPhysical DigestionzTeethzStomachzBile saltzby churning zby emulsifying action in duodenumz bycuttingcuttingchewingchewinggrindinggrindingbitingbitingtearingtearingNextNextBackBackChemical Digestionzinvolved the change of the chemical structures of foodze.g. zthis involves digestive enzymeszno di
16、gestion on: water, glucose, simple sugars, minerals, vitaminsStarchStarchmaltosemaltosemaltosemaltoseNextNextBackBackamylaseMouthzsaliva is a digestive juice consisting of yamylaseymucusywaterzit is slightly alkalineNextNextBackBackStomachzcardiac sphincterzaction of proteaseszaction of hydrochloric
17、 acidyprovide acidic medium for proteaseszpyloric sphincterNextNextBackBackproteaseDuodenumzpancreatic juiceyamylase, proteases, lipaseszbile ycolour, composition, no enzymatic propertyzintestinal juiceycarbohydrases, proteasesNextNextBackBackCaecum,Colon & Rectumzno enzyme secretion in omnivores an
18、d carnivoreszspecific function in herbivoresymicro-organismsycellulaseyweakness NextNextBackBackAbsorption IIztake place in ileumzstarts at stomach / duodenumzvillusNextNextBackBackVilluszfinger like projectionsyincrease S.A./Vzone cell thickzmany blood vesselszcentral lacteal villuslactealBlood ves
19、selsepitheliumNextNextBackBackTransport of absorbed foodlumenBackBackepitheliumblood capillarieshepatic portal veinliverhepatic veinvena cavaheart (general circulation)NextNextWater soluble foodFat soluble foodlumenepitheliumlactealLymph vesselvena cavaheart (general circulation)Assimilation IIzfate
20、 of absorbed food substancesyglucoseyamino acidsyfatszroles of liver NextNextBackBackFate of glucosezfor releasing energyzexcess glucose will be stored asyglycogenyfatszstorage siteyliverymuscleNextNextBackBackFate of amino acidszfor making new cells and tissueszexcess amino acids will be deaminated
21、zproduct: ureazsite of excretion:ykidneyNextNextBackBackFate of fatszfor formation of cell membraneszexcess fats will be storedyfatszstorage site yadipose tissueNextNextBackBackRoles of liverzregulating blood glucose levelzstoring glycogenzstoring iron and vitaminszbreaking down excess amino acidsNe
22、xtNextBackBackDiarrhoeazCauses: y(1) bacterial infectiony(2) eating poisonous substanceszConsequences:y(1) quick movement of intestiney(2) food passes along the canal quicklyy(3) less water absorbedy(4) watery faeces producedNextNextBackBackConstipationzCauses:yeating too less dietary fibresyeating
23、too less fresh fruitzConsequences:y(1) slow movement of intestiney(2) food passes along the canal slowlyy(3) much water absorbedy(4) hard, dried faeces producedNextNextBackBackEnd of the ChapterBy Nicholas Lai(PLKWCC)GlossaryzActive transport: movement of molecules against concentration gradient wit
24、h the utilizing of energy.zAmylase: an enzyme that convert starch to maltose.zCarbohydrases: enzymes digest carbohydrates into simpler molecules.zCarnivores: organisms feed on animals onlyzDiffusion: movement of molecules from a region of high concentration to a region of low concentrationzHerbivores: organisms feed on plants onlyzLipases: enzymes digest fat/oil into simpler moleculesGlossaryzMucus: a sticky substance secreted by epithelial cells of the gutzOmnivores: organisms feed on animals and plants zProteases: enzymes digest protein into simpler molecules
