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The Nutritional Connection

The Nutritional Connection. Chapter 11. Learning Objectives:. Become familiar with the anatomy and physiology of the digestive system Identify the nutritional requirements and components of a healthy diet Outline the official nutritional advice provided for Canadians

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The Nutritional Connection

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  1. The Nutritional Connection Chapter 11 Sport Books Publisher

  2. Learning Objectives: • Become familiar with the anatomy and physiology of the digestive system • Identify the nutritional requirements and components of a healthy diet • Outline the official nutritional advice provided for Canadians • Understand the unique nutritional needs of various populations • Appreciate the effects of nutrition on athletic performance Sport Books Publisher

  3. Introduction Sport Books Publisher

  4. Introduction Promotion of energy and vigor Development of chronic illness and disease NUTRITIONAL HABITS Sport Books Publisher

  5. Nutrition Basics • Choose foods that provide the necessary nutrients • Limit those foods associated with disease • Don’t assume that a healthy diet needs to be fat-free, low-sugar, and high-fibre all the time • When making food choices, consider: • VARIETY • BALANCE; and • MODERATION Sport Books Publisher

  6. The Digestive System Sport Books Publisher

  7. The Digestive System • The role of the digestive system is to: • Produce energy from food ingested • To transfer energy-rich nutrients, water, and electrolytes into your body’s internal environment • Composed of numerous structures and organs that work together • The digestive tract forms a continuous route from mouth to anus • The contents of the digestive tract are actually part of the external environment until absorbed through the intestinal wall Sport Books Publisher

  8. The Gastrointestinal Tract Digestive Tract • Mouth • Pharynx • Esophagus • Stomach • Small intestine • Large intestine (colon) • Rectum • Anus Glandular Organs • Salivary glands • Liver • Gall bladder • Pancreas Sport Books Publisher

  9. Basic Processes of the Digestive System • Digestion • Secretion • Absorption • Motility Sport Books Publisher

  10. Digestion • Processes that dissolve and break down foods into molecules that can be absorbed by the body Sport Books Publisher

  11. Secretion • The release of substances from exocrine glands • Works closely with the digestion process • Includes many secretions, some of which are: • Saliva by salivary glands • Hydrochloric acid by the stomach • Bile by the liver Sport Books Publisher

  12. Absorption • Uptake of digested molecules across a layer of epithelial cells lining the gastrointestinal wall • Molecules enter the blood or lymph to be distributed to body cells Sport Books Publisher

  13. Motility • The muscular contractions that mix and move the contents of the digestive tract forward • Propels the contents of the digestive tract forward • Mixes food with digestive juices that promote digestion Sport Books Publisher

  14. The Digestive System • The digestive system aims to absorb maximally • Waste material excreted via the gastrointestinal tract is called ‘feces’ • Feces consist mainly of bacteria and undigested material (including fibre) Sport Books Publisher

  15. Functional Overview of the Gastrointestinal Organs Sport Books Publisher

  16. Functional Overview of GI Organs:The Salivary Glands • Digestion begins in the mouth • The mechanical breakdown of food is achieved by chewing • Saliva produced by the salivary glands • Three salivary glands in the head Sport Books Publisher

  17. Functional Overview of GI Organs:The Salivary Glands • Saliva contains mucus that moistens and lubricates food • Saliva also contains ‘amylase’ • Amylase is an enzyme that catalyzes the breakdown of carbohydrates Sport Books Publisher

  18. Functional Overview of GI Organs:The Mouth and Throat • Voluntary swallowing is initiated in the oropharynx (posterior mouth) • The bolus of food moves to the pharynx • Involuntary swallowing occurs in the esophagus • ‘Peristalsis’ is the involuntary contraction of muscles and is involved in moving food to the stomach Sport Books Publisher

  19. Functional Overview of GI Organs:The Stomach • A sac-like organ • Serves as a storage site • Dissolves and partially digests food • Prepares food for optimal digestion and absorption in the small intestine Sport Books Publisher

  20. Functional Overview of GI Organs:The Stomach • Glands in the stomach secrete hydrochloric acid (HCl) • HCl dissolves particulate matter in food (except fat) • HCl also kills some bacteria that is ingested with food Sport Books Publisher

  21. Functional Overview of GI Organs:The Stomach • The precursor ‘pepsinogen’ forms the enzyme ‘pepsin’ • Pepsin begins protein digestion • Amylase (from the salivary glands) continues to break down carbohydrates Sport Books Publisher

  22. Functional Overview of GI Organs:The Stomach • Little absorption occurs across the stomach wall Sport Books Publisher

  23. Functional Overview of GI Organs:The Small Intestine • Site of completion of digestion • Site where most absorption occurs • Approximately nine feet in length • Three segments: • Duodenum • Jejunum • Ileum • Most absorption occurs in the duodenum and jejunum (vitamins, minerals, water) Sport Books Publisher

  24. Hydrolytic Enzymes Carbohydrates AMYLASE Monosaccharides Sport Books Publisher

  25. Hydrolytic Enzymes Proteins PEPSIN Amino Acids Sport Books Publisher

  26. Hydrolytic Enzymes Fats LIPASE Fatty Acids Sport Books Publisher

  27. Functional Overview of GI Organs:The Pancreas • Secretes digestive enzymes • Secretes an alkaline fluid mainly of bicarbonate ions • The alkaline fluid counteracts the acidity of the contents of the stomach to protect the small intestine • Alkaline substance also maintains an optimal pH range for enzymatic functions Sport Books Publisher

  28. Functional Overview of GI Organs:The Liver • Secretes ‘bile’ • Bile contains cholesterol, bicarbonate ions, and bile salts • Bile salts are essential for fat digestion and absorption • Bile is stored in the gall bladder Sport Books Publisher

  29. Absorption in the Small Intestine • Absorption within the small intestine occurs via: • DIFFUSION (Fatty Acids) • OSMOSIS (Water) • ACTIVE TRANSPORT (Mineral Ions) • CARRIER-MEDIATED TRANSPORT (Monosaccharides and Amino Acids) Sport Books Publisher

  30. Functional Overview of GI Organs:The Large Intestine • Upon reaching the large intestine, very little water remains, and salts and undigested material are left • Here, the material is further concentrated by further reabsorption of salt and water Sport Books Publisher

  31. Functional Overview of GI Organs:The Large Intestine • When reabsorption is complete, the feces move to the rectum as a result of involuntary contractions (peristalsis) • The coordinated relaxation of sphincter muscles results in defecation Sport Books Publisher

  32. Nutritional Requirements: Types and Sources of Nutrients Sport Books Publisher

  33. Nutrition • The science of food and how the body uses it in health and disease Sport Books Publisher

  34. Proteins Fats Carbohydrates Vitamins Minerals Water In this context, ‘essential’ refers to nutrients that the body is unable to manufacture (or not in sufficient quantities) They must be obtained from the diet Essential Nutrients Sport Books Publisher

  35. Essential Nutrients • Necessary for energy • Needed for the building and maintenance of tissues • Relied upon for the regulation of body functions Sport Books Publisher

  36. Energy-Providing Nutrients • Three nutrients provide the body with energy • Proteins • Fats • Carbohydrates Sport Books Publisher

  37. Energy Measurements • Energy is expressed in ‘kilocalories’ • 1 kilocalorie = 1000 calories • Kilocalorie = Calorie (note capital ‘C’) • 1 kilocalorie = heat required to raise the temperature of 1kg of water 1°C • An average person requires approximately 2000 kilocalories per day Sport Books Publisher

  38. Calorie Densities of Various Energy Sources Sport Books Publisher

  39. Proteins • Found in every living cell • Act as structural components for: • Muscles • Bones • Blood • Enzymes • Some hormones • Cell membranes Sport Books Publisher

  40. Proteins • Composed of chains of amino acids • 20 commonly recognized amino acids • Nine essential (can not be synthesized) amino acids • Histidine • Isoleucine • Leucine • Lysine • Methionine • Phenylalanine • Threonine • Tryptophan • Valine Sport Books Publisher

  41. Protein • Individual sources of protein are ‘complete’ if they supply all nine essential amino acids • Complete protein sources include animal products such as meat, cheese, fish, eggs, poultry and milk Sport Books Publisher

  42. Protein • ‘Incomplete’ protein sources include those foods that do not contain all nine essential amino acids • Usually from plant sources such as grains, beans, peas, and nuts • Still good sources of amino acids • Foods must be combined to get all amino acids (rice and beans for example) Sport Books Publisher

  43. Protein • Protein should comprise 10-15% of total caloric intake • Protein consumed in excess of needs is stored as fat • Inadequate protein consumption can lead to muscle wasting Sport Books Publisher

  44. Fats • Also known as lipids • Concentrated source of energy • Fat serves to • Provide a source of energy • Insulate the body • Cushion organs • Aid the absorption of fat-soluble vitamins • Add flavour and texture to foods Sport Books Publisher

  45. Fats • Fats in food are mostly triglycerides • Include a glycerol (an alcohol) • Three fatty acid molecules Sport Books Publisher

  46. Fats • Fats can be classified as • Saturated • Monounsaturated • Polyunsaturated • Based on the degree of saturation or number of double bonds that exist between carbon atoms • No double bonds = saturated • One double bond = monounsaturated • Two or more double bonds = polyunsaturated Sport Books Publisher

  47. Saturated Fat Monounsaturated Fat Polyunsaturated Fat Sport Books Publisher

  48. Saturated Fats • Food usually contains more than one type of fat • The dominant fat determines the characteristics of the fat • Saturated fats are solid at room temperature • Saturated fat is found predominantly in animal products • Saturated fat has also been linked to cardiovascular disease Sport Books Publisher

  49. Unsaturated Fats • Monounsaturated and polyunsaturated fats usually come from plant sources • Unsaturated fat is liquid at room temperature (oil) • More desirable, not linked to cardiovascular disease • Unsaturated fats appear to lower blood cholesterol • Also shown to reduce the risk of heart disease Sport Books Publisher

  50. Sport Books Publisher

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