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Digestion & Sports Nutrition

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

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Digestion & Sports Nutrition

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  1. Digestion & Sports Nutrition

  2. 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

  3. 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

  4. 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

  5. Digestive Functions • Series of integrated steps: • Ingestion • Materials enter the digestive tract • Mouth • Active process • Mechanical Digestion • Physical manipulation & distortion • Materials easily propel along digestive tract • Increases SA – Enzymatic Reactions • Teeth • Tearing & Crushing • Tongue • Squashing & Compaction • Stomach • Swirling, Mixing & Churning

  6. Digestive Functions • Digestion • Chemical breakdown of food into small organic fragments • Facilitated by enzymes • Assists absorption • Secretion • Release: • Water • Acids & Enzymes • Buffers & Salts

  7. Digestive Functions • Absorption • Movement of organic substrates, electrolytes, vitamins & water • Epithelium -bloodstream • Assimilated by cells • Cells take in & make use of digestive food • Energy • Growth & Repair • Excretion • Elimination of waste products • Defecation • Ejection of materials usually as faeces

  8. Digestive FunctionsEnzymes • Are 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 digest • Amylases • Lipases • Proteases • Proteins & Amino Acids – Enzymes (as Catalysts)http://nutrition.jbpub.com/resources/animations.cfm?id+1&debug=0

  9. Digestive Functions Enzymes

  10. Movement Of Digestive Materials • Digestive Tract • Consists of layers of smooth muscle tissue • Assists with movement of materials along the tract • Peristalsis • Segmentation • Digestion & Absorption – Peristalsis & Segmentation –http://nutrition.jbpub.com/resources/animations.cfm?id+1&debug=0 • Peristalsis • Waves of muscular contraction behind the digestive contents • Moves food along the length of the digestive tract • Segmentation • Occurs in: • Small & Large Intestines • Movements churn & fragment digestive materials, mixing with intestinal secretions

  11. Exploring The Digestive System • Digestive Tract • Begins – Oral Cavity • Pharynx • Oesophagus • Stomach • Small Intestine • Large Intestine • Rectum • Ends – Anus • Structures • Overlapping functions • Each have areas of specialisation & distinctive characteristics

  12. Exploring The Digestive System • The Oral Cavity • Functions: • Analysis of materials before swallowing • Mechanical processing • Teeth & Tongue • Lubrication • Saliva & Mucus • Limited digestion • Carbohydrates • Tongue • Functions: • Mechanical processing • Compression, abrasion & distortion • Manipulation • Sensory analysis • Touch • Temperature • Taste • Secretion • Mucus & Enzymes

  13. Exploring The Digestive System • Salivary Glands • 3 pairs with distinctive cellular organisation • Produce saliva with different properties • Teeth • Mastication of food • Breaks down food tissues • Saturates materials with salivary secretions & enzymes • Pharynx • Common passageway: • Solid Food • Liquids • Air

  14. Exploring The Digestive System • Oesophagus • Hollow muscular tube • Function: • Carry solid food & liquids to the stomach • Swallowing • Complex process • Divided into 3 phases: • Buccal Phase • Pharyngeal Phase • Oesophageal Phase • Stomach • Shape of an expanded J • Functions: • Storage • Mechanical breakdown • Disruption of chemical bonds • Acids/Enzymes

  15. Exploring The Digestive System • Small Intestine • Plays a primary role in the digestion & absorption of nutrients • 90% nutrient absorption • Three subdivisions: • Duodenum • Jejunum • Ileum • Facilitates absorption through: • Intestinal Lining • Plicae • Series of transverse folds • Greatly increase SA • Intestinal Villi • Series of finger like projections • Extensive network of capillaries

  16. Exploring The Digestive System • Large Intestine • Horseshoe-shaped • Inferior - stomach/liver • Divided into 3 parts: • Cecum • Colon • Rectum • Major functions: • Reabsorption of H20 & compaction of intestinal contents into faeces • Absorption of vitamins • Storage of fecal material prior to defecation

  17. Exploring The Digestive System • Pancreas • Posterior to stomach • Elongated, pinkish grey organ • Primarily exocrine organ: • Produces digestive enzymes/buffers • Liver • Largest visceral & most versatile organ • Large, firm, reddish brown organ • Provides essential metabolic & synthetic services: • Metabolic Regulation • Hematological Regulation • Bile Production

  18. Exploring The Digestive System • Metabolic Regulation • Carbohydrate Metabolism • Lipid Metabolism • Amino Acid Metabolism • Removal Of Wastes • Vitamin Storage • Mineral Storage • Drug Inactivation • The Gallbladder • Hollow, pear-shaped, muscular organ • 2 major functions: • Bile Storage • Bile Modification

  19. Digestion & Absorption • Typical meal contains a mixture: • Carbohydrates • Proteins • Lipids • Minerals • Vitamins • Water • Digestive system handles each of these components differently • Large organic molecules must be broken down via digestion before absorption can occur

  20. Digestion & Absorption • Digestion: • 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 Energy • Passive Diffusion • Endocytosis • Facilitated Diffusion • Assimilation: • Soluble food passes from bloodstream into all cells

  21. Digestion & Absorption • Digestive 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 ATP • Growth and repair

  22. Digestion & Absorption • Most ingested organic materials are complex chains of simpler molecules: • Carbohydrate • Monosaccarides • Protein • Amino Acids • Lipids • Fatty Acids • Digestive enzymes break the bonds between the component molecules • Hydrolysis • 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

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