digestion & sports nutrition

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Digestion & Sports Nutrition. The Digestive System An Overview. Little thought unless it malfunctions. Spend hours filling & emptying it. Cells perform metabolic reactions that provide energy for the synthesis of ATP. Reactions require: Oxygen: Circulatory System Respiratory System - PowerPoint PPT Presentation


  • Digestion & Sports Nutrition

  • The Digestive SystemAn OverviewLittle thought unless it malfunctions.Spend hours filling & emptying it.Cells perform metabolic reactions that provide energy for the synthesis of ATP.Reactions require:Oxygen:Circulatory SystemRespiratory SystemOrganic Molecules Intracellular Enzymes:Digestive SystemCirculatory & Lymphatic Systems

  • The Digestive SystemAn OverviewDigestive System provides:EnergyFuel to keep bodys cells runningBuilding BlocksGrowthRepairDigestive System consists of:Digestive TractVarious Accessory Organs

  • The Digestive SystemAn OverviewDigestive Tract:Oral CavityPharynxOesophagusStomachSmall IntestineLarge IntestineRectumAccessory OrgansTeethTongueGlandular OrgansSalivary GlandsLiverGall BladderPancreas

  • Digestive FunctionsSeries of integrated steps:IngestionMaterials enter the digestive tractMouthActive process

    Mechanical DigestionPhysical manipulation & distortionMaterials easily propel along digestive tractIncreases SA Enzymatic ReactionsTeethTearing & CrushingTongueSquashing & CompactionStomachSwirling, Mixing & Churning

  • Digestive FunctionsDigestionChemical breakdown of food into small organic fragments Facilitated by enzymesAssists absorptionSecretionRelease:WaterAcids & EnzymesBuffers & Salts

  • Digestive FunctionsAbsorptionMovement of organic substrates, electrolytes, vitamins & water Epithelium -bloodstream Assimilated by cellsCells take in & make use of digestive foodEnergyGrowth & Repair

    ExcretionElimination of waste productsDefecationEjection of materials usually as faeces

  • Digestive FunctionsEnzymesAre proteins that act as catalystsPlay an important part in digestion.Speed up process of breaking food down into chemically simpler substances - more solubleSecreted by salivary glands, tongue, stomach & pancreasFound in saliva & digestive juicesAre specialised and can be divided into groups according to the food they digestAmylasesLipases ProteasesProteins & Amino Acids Enzymes (as Catalysts) http://nutrition.jbpub.com/resources/animations.cfm?id+1&debug=0

  • Digestive Functions Enzymes

  • Movement Of Digestive MaterialsDigestive TractConsists of layers of smooth muscle tissueAssists with movement of materials along the tractPeristalsisSegmentation

    Digestion & Absorption Peristalsis & Segmentation http://nutrition.jbpub.com/resources/animations.cfm?id+1&debug=0

    PeristalsisWaves of muscular contraction behind the digestive contentsMoves food along the length of the digestive tractSegmentationOccurs in:Small & Large IntestinesMovements churn & fragment digestive materials, mixing with intestinal secretions

  • Exploring The Digestive SystemDigestive TractBegins Oral CavityPharynxOesophagusStomachSmall IntestineLarge IntestineRectumEnds Anus

    StructuresOverlapping functionsEach have areas of specialisation & distinctive characteristics

  • Exploring The Digestive SystemThe Oral CavityFunctions:Analysis of materials before swallowingMechanical processingTeeth & TongueLubricationSaliva & MucusLimited digestionCarbohydratesTongueFunctions:Mechanical processingCompression, abrasion & distortionManipulationSensory analysisTouchTemperatureTasteSecretionMucus & Enzymes

  • Exploring The Digestive SystemSalivary Glands3 pairs with distinctive cellular organisationProduce saliva with different propertiesTeethMastication of foodBreaks down food tissuesSaturates materials with salivary secretions & enzymes

    PharynxCommon passageway:Solid FoodLiquidsAir

  • Exploring The Digestive SystemOesophagusHollow muscular tubeFunction:Carry solid food & liquids to the stomachSwallowingComplex processDivided into 3 phases:Buccal PhasePharyngeal PhaseOesophageal PhaseStomachShape of an expanded JFunctions:Storage Mechanical breakdownDisruption of chemical bondsAcids/Enzymes

  • Exploring The Digestive SystemSmall IntestinePlays a primary role in the digestion & absorption of nutrients90% nutrient absorptionThree subdivisions:DuodenumJejunumIleumFacilitates absorption through:Intestinal LiningPlicaeSeries of transverse folds Greatly increase SAIntestinal VilliSeries of finger like projectionsExtensive network of capillaries

  • Exploring The Digestive SystemLarge IntestineHorseshoe-shapedInferior - stomach/liverDivided into 3 parts:CecumColonRectum

    Major functions:Reabsorption of H20 & compaction of intestinal contents into faeces Absorption of vitaminsStorage of fecal material prior to defecation

  • Exploring The Digestive SystemPancreasPosterior to stomachElongated, pinkish grey organPrimarily exocrine organ:Produces digestive enzymes/buffersLiverLargest visceral & most versatile organLarge, firm, reddish brown organProvides essential metabolic & synthetic services:Metabolic RegulationHematological RegulationBile Production

  • Exploring The Digestive SystemMetabolic RegulationCarbohydrate MetabolismLipid MetabolismAmino Acid MetabolismRemoval Of WastesVitamin StorageMineral StorageDrug InactivationThe GallbladderHollow, pear-shaped, muscular organ2 major functions:Bile StorageBile Modification

  • Digestion & AbsorptionTypical meal contains a mixture:CarbohydratesProteinsLipidsMineralsVitaminsWater

    Digestive system handles each of these components differentlyLarge organic molecules must be broken down via digestion before absorption can occur

  • Digestion & AbsorptionDigestion: Breakdown of food into smaller particles or individual nutrientsAbsorption: Movement of molecules across the gastrointestinal tract into the circulatory system

    Four mechanisms of absorption:Active TransportRequires EnergyPassive DiffusionEndocytosisFacilitated DiffusionAssimilation:Soluble food passes from bloodstream into all cells

  • Digestion & AbsorptionDigestive systemBreaks down the physical structure of ingested materialDisassemble the component molecules into smaller fragments = absorptionMolecules released into bloodstream will be absorbed by cells (assimilation):Provide energy of synthesis of ATPGrowth and repair

  • Digestion & Absorption Most ingested organic materials are complex chains of simpler molecules:CarbohydrateMonosaccaridesProteinAmino AcidsLipidsFatty Acids Digestive enzymes break the bonds between the component moleculesHydrolysis Chemical reaction where one or more water molecules split into hydrogen & hydroxide ionshttp://wps.prenhall.com/esm_freeman_biosci_1/0,6452,500719-,00.html