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

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