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Unit 3

Unit 3. NUTRITION AND DIGESTION. 3.1WHAT IS NUTRITION?. The process of nutrition allows living beings to obtain the matter and the energy they need for making their own matter and for carrying out their vital functions . 3.2 KINDS OF ORGANISMS ACCORDING TO NUTRITION.

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Unit 3

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  1. Unit 3 NUTRITION AND DIGESTION

  2. 3.1WHAT IS NUTRITION?

  3. Theprocess of nutritionallows living beingstoobtainthematter and theenergytheyneedformakingtheirownmatter and forcarryingouttheir vital functions.

  4. 3.2 KINDS OF ORGANISMS ACCORDING TO NUTRITION

  5. Living beings can be placed intotwogroupsaccordingtowhattheyneedfromtheenvironment: • Producer organisms:theytakeinorganicsubstancesfromtheenvironment. Theyalsoneed a source of energythatthey can use. Example: photosynthesis→sunlight. • Consumerorganisms: theyneedtotakefoodfromtheenvironment, thisisalwaysorganicmatteralreadyformedbyother living beings.

  6. 3.3 HOW SUBSTANCES ARE TAKEN IN AND EXPELLED

  7. Theprocess of nutritionmeansthatvarioussubstancesentertheorganism and otherdifferentsubstances are expelledeitherbecausetheyaren´tusefulorbecausethey are toxic.

  8. SUBSTANCES WHICH ENTER THE ORGANISM

  9. PRODUCTS EXPELLED BY THE ORGANISM

  10. 3.4 THE SYSTEMS INVOLVED IN HUMAN NUTRITION

  11. Theprocessesrelatedtonutrition are carriedoutbyfourorgansystems in ourbody: thedigestivesystem, therespiratorysystem, thecirculatorysystem and theexcretorysystem. Allthesesystems and processes are controlledbythenervoussystem.

  12. THE SYSTEMS RELATED TO NUTRITION Respiratorysystem Digestivesystem Circulatorysystem Excretorysystem

  13. 3.5 THE DIGESTIVE PROCESS

  14. Animalsobtainproteins, lipids and sugarsfromfood. Thisis a verydifficulttask and itis done bythedigestivesystem. There are threephases in foodprocessing: digestion, absorption and theexpulsion of waste.

  15. Themovement of foodthroughthedigestivetractis done thankstoperistalticmovements. Theseconsist of thenarrowing of thetubethroughthecontraction of themuscles of thewalls. Themusclescontractsuccessively in such a waythattheprogressivenarrowingpushesthefoodregardless of the position of thebody. Onocassion, such as vomiting, reverse peristalticmovementsoccur.

  16. PERISTALTIC MOVEMENTS

  17. 3.6 DIGESTION

  18. Accordingtothechanges in food, digestion can be: • Mechanical:Itconsists of cutting, crushing, removing and dilutingfoods, bringingaboutphysicalchanges. • Chemical:Itis done throughtheaction of varioussubstanceswhichattackthefood and bringaboutchemicalchanges in it, breakingitdownintosubstanceswhich are smaller.

  19. STAGES OF DIGESTION

  20. Digestion in themouthis a result of mastication and salivation. Masticationcuts and crushesthefood. Salivais a liquidwhichisproducedbythesalivaryglands in themouth, there are threepairs of glandscalledthe sublingual, thesubmaxilary and theparotoidglands. Saliva containssubstanceswhichactchemicallyonfood.

  21. Afterswallowing, foodreachesthestomachwheregastricdigestionbegins. Physical and chemicaldigestionalsooccursimultaneously in thestomach. Thefoodmoves and issoftenedthankstothemovement of thewalls of thestomach and itismixedwithgastricjuices. As a result of gastricdigestion, a pulpknown as chymeisproduced and thisgraduallyleavesthestomachviathepylorus.

  22. Thefirstsection of thesmallintestine, theduodenum, continuesthechemicaldigestion of thefood. There, thechymeismixedwithintestinal juices (madebythewalls of theduodenum), bile (producedbytheliver) and pancreaticjuice (fromthepancreas). Theresultis a milky fluid known as chyle in whichthesubstancesthatthebody can assimilatehavebeenseparated.

  23. 3.7 ABSORPTION AND THE ELIMINATION OF WASTE

  24. Thechylepassesfromtheduodenumtothefollowingparts of thesmallintestine, thejejunum and theileum. The intestinal walls are very rough and filledwith intestinal hairs, deepfolds in thewall and manybloodvessels.

  25. Theabsorptionconsists of theusefulsubstances in thefoodcrossingthroughthe intestinal wall and intothebloodvessels. Thebloodthentakesthemtoallthecells in thebody.

  26. Theremains of thechylewhich can notbeusedpassintothelargeintestine. In thefirstpart, theascending colon, beginstorecoverwater and someions. Thisprocesscontinues in thetransverse colon. The final tract of thelargeintestineisthedescending colon whichstoresthefaeces. When a certainamount has beenformed, thefaecespasstotherectumreadytobeexpelledviatheanus.

  27. Digestivesystem

  28. Mouth • Liver • Gallbladder • Vermiformappendix • Anus • Largeintestine: ascending colon (), transverse colon () and descending colon() • Small intestine: duodenum (), jejunum () and ileum () • Spleen • Stomach • Pancreas • Pharynx • Oesophagus • Salivaryglands • Rectum

  29. teeth Thetooth formula is 4I+2C+4PM+6M per jaw. Adultshave a total of 32 teeth. Thethird molar, alsocalledthewisdomtooth, appears in adult-hood.

  30. Molar 3rd (Wisdomtooth) • Molar 2nd • Molar 1st • Pre-molar 2nd • Pre-molar 1st • Canine • Incisors

  31. Thestomach

  32. Oesophagus • Loweroesophagealsphincter • Cardia • Stomachfundus • Gastricfolds • Stomach, greatercurvature • Stomach, lessercurvature • Layers of thewall of thestomach (): mucus tunic (), muscular tunic () and seroustunic () • Pylorus • Initialstage of theduodenum

  33. Associatedglands and theduodenum Theliver and thepancreas share the final stage of thebileductwhichreleasestheproducts of bothglands (bile and gastricjuices) intotheduodenum. Thisduct opens intotheduodenumthroughwhatisknown as theampulla of Vater

  34. Stomach • Pancreas • Liver • Duodenum • Gallbladder • Cysticconduct • Bileduct • Pancreaticduct • Ampulla of Vater

  35. VOCABULARY

  36. Nutrition • Mechanicaldigestion • Chemicaldigestion • Mastication • Saliva • Chyme • Chyle

  37. Nutrition: Itistheprocessthatallows living beingstoobtainthematter and theenergytheyneedformakingtheirownmatter and forcarryingouttheir vital functions. • Mechanicaldigestion: Itconsists of cutting, crushing, removing and dilutingfoods, bringingaboutphysicalchanges. • Chemicaldigestion:Itis done throughtheaction of varioussubstanceswhichattackthefood and bringaboutchemicalchanges in it, breakingitdownintosubstanceswhich are smaller.

  38. Mastication:Itis a process in whichthefoodiscut and crushed. • Saliva:Itis a liquidwhichisproducedbythesalivaryglands in themouth and containssubstanceswhichactchemicallyonfood. • Chyme:Itis a pulpformedbyfood and gastricjuiceswhichistheresult of gastricdigestion. • Chyle:Itis a milky fluid formedbythechymemixedwith intestinal juices, bile and pancreaticjuice, in whichthesubstancesthatthebody can assimilatehavebeenseparated.

  39. UNIT MAP

  40. TMUOH • ILVRE • GLAL BEADLDR • VOMERIFRM NAXPEPDI • UASN • OAGESPHOUS • ALSVAIRY NGADLS • URCTEM • SOACTMH • ENPARASC • YPNARXH

  41. ELRAG NTNETISEI • EDSCDINGEN OLCON • SMALL IENESTITN • DEOUDNMU • AICNSDNGE OCONL • UJUNJME • ILMEU • NTVASERSRE LCONO • LSEPEN

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