Download - Digestion & Sports Nutrition
Digestion & Sports Nutrition
The Digestive SystemAn 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
Organic Molecules – Intracellular Enzymes: Digestive System Circulatory &
Lymphatic Systems
The Digestive SystemAn Overview Digestive System provides:
Energy Fuel to keep body’s
cells running Building Blocks
Growth Repair
Digestive System consists of: Digestive Tract Various Accessory Organs
The Digestive SystemAn Overview Digestive Tract:
Oral Cavity Pharynx Oesophagus Stomach Small Intestine Large Intestine Rectum
Accessory Organs Teeth Tongue Glandular Organs
Salivary Glands Liver Gall Bladder Pancreas
Digestive FunctionsSeries of integrated
steps:
IngestionMaterials enter the
digestive tractMouth
Active process
Mechanical DigestionPhysical manipulation &
distortionMaterials easily propel
along digestive tract Increases SA – Enzymatic
ReactionsTeeth
Tearing & CrushingTongue
Squashing & CompactionStomach
Swirling, Mixing & Churning
Digestive FunctionsDigestion
Chemical breakdown of food into small organic fragments Facilitated by enzymesAssists absorption
SecretionRelease:
WaterAcids & EnzymesBuffers & Salts
Digestive FunctionsAbsorption
Movement of organic substrates, electrolytes, vitamins & water Epithelium -bloodstream Assimilated by cells
Cells take in & make use of digestive foodEnergyGrowth & Repair
ExcretionElimination of waste
productsDefecation
Ejection of materials usually as faeces
Digestive FunctionsEnzymesAre proteins that act as
catalysts
Play an important part in digestion.
Speed up process of breaking food down into chemically simpler substances - more soluble
Secreted by salivary glands, tongue, stomach & pancreas
Found in saliva & digestive juices
Are specialised and can be divided into groups according to the food they digestAmylasesLipases Proteases Proteins & Amino Acids – Enzymes
(as Catalysts) http://nutrition.jbpub.com/resources/animations.cfm?id+1&debug=0
Digestive Functions Enzymes
Movement Of Digestive MaterialsDigestive Tract
Consists of layers of smooth muscle tissue
Assists 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 contents
Moves food along the length of the digestive tract
SegmentationOccurs in:
Small & Large IntestinesMovements churn &
fragment digestive materials, mixing with intestinal secretions
Exploring The Digestive SystemDigestive Tract
Begins – Oral CavityPharynxOesophagusStomachSmall IntestineLarge IntestineRectum
Ends – Anus
StructuresOverlapping
functionsEach have areas of
specialisation & distinctive characteristics
Exploring The Digestive SystemThe Oral Cavity
Functions:Analysis of materials
before swallowingMechanical
processingTeeth & Tongue
LubricationSaliva & Mucus
Limited digestionCarbohydrates
TongueFunctions:
Mechanical processingCompression, abrasion &
distortionManipulationSensory analysis
TouchTemperatureTaste
SecretionMucus & Enzymes
Exploring The Digestive SystemSalivary Glands
3 pairs with distinctive cellular organisation
Produce saliva with different properties
TeethMastication of food
Breaks down food tissues
Saturates materials with salivary secretions & enzymes
PharynxCommon passageway:
Solid FoodLiquidsAir
Exploring The Digestive SystemOesophagus
Hollow muscular tubeFunction:
Carry solid food & liquids to the stomach
SwallowingComplex processDivided into 3 phases:
Buccal PhasePharyngeal PhaseOesophageal Phase
StomachShape of an expanded JFunctions:
Storage Mechanical breakdownDisruption of chemical
bondsAcids/Enzymes
Exploring The Digestive SystemSmall Intestine
Plays a primary role in the digestion & absorption of nutrients
90% nutrient absorption
Three subdivisions:Duodenum Jejunum Ileum
Facilitates absorption through:
Intestinal LiningPlicae
Series of transverse folds
Greatly increase SA Intestinal Villi
Series of finger like projections
Extensive network of capillaries
Exploring The Digestive SystemLarge Intestine
Horseshoe-shaped Inferior - 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 SystemPancreas
Posterior to stomachElongated, pinkish
grey organPrimarily exocrine
organ:Produces digestive
enzymes/buffers
LiverLargest visceral & most
versatile organLarge, firm, reddish
brown organProvides essential
metabolic & synthetic services:Metabolic RegulationHematological
RegulationBile Production
Exploring The Digestive System
Metabolic RegulationCarbohydrate
MetabolismLipid MetabolismAmino Acid
MetabolismRemoval Of WastesVitamin StorageMineral StorageDrug Inactivation
The GallbladderHollow, pear-shaped,
muscular organ2 major functions:
Bile StorageBile Modification
Digestion & AbsorptionTypical meal contains a
mixture:CarbohydratesProteinsLipidsMineralsVitaminsWater
Digestive system handles each of these components differently
Large organic molecules must be broken down via digestion before absorption can occur
Digestion & AbsorptionDigestion:
Breakdown of food into smaller particles or individual nutrients
Absorption: Movement of
molecules across the gastrointestinal tract into the circulatory system
Four mechanisms of absorption:Active Transport
Requires EnergyPassive DiffusionEndocytosisFacilitated Diffusion
Assimilation:Soluble food passes
from bloodstream into all cells
Digestion & AbsorptionDigestive system
Breaks down the physical structure of ingested material
Disassemble the component molecules into smaller fragments = absorption
Molecules 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:Carbohydrate
MonosaccaridesProtein
Amino AcidsLipids
Fatty Acids
Digestive enzymes break the bonds between the component moleculesHydrolysis
Chemical reaction where one or more water molecules split into hydrogen & hydroxide ions
http://wps.prenhall.com/esm_freeman_biosci_1/0,6452,500719-,00.html