The Human Body: From Food to Fuel

1. 1 The Human Body: From Food to Fuel

2. 2 Chapter 4 Objectives Provide an overview of the structures, mechanisms, and processes of the GI tract. Understand how food is digested and absorbed within the body. Explain how foods are transported after they are digested and absorbed. Describe how the body keeps the complex processes of digestion, absorption, and nutrient transport running smoothly. Explain various influences on digestion and absorption along with various nutrition and GI disorders.

3. 3 The Gastrointestinal Tract Organization Mouth ? anus Accessory organs Salivary glands, liver, pancreas, gallbladder Functions Ingestion Transport Secretion Digestion Absorption Elimination

4. 4 Overview of Digestion Physical movement Peristalsis Segmentation Chemical breakdown Enzymes Other secretions

5. 5 Overview of Absorption Types of absorptive processes Passive Diffusion

6. 6 Facilitated Diffusion

7. 7 ActiveTransport

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9. 9 Assisting Organs Salivary glands Moisten food Supply enzymes Liver Produces bile Enterohepatic circulation Gallbladder Stores and secretes bile Pancreas Secretes bicarbonate Secretes enzymes

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12. 12 Digestion and Absorption Mouth Enzymes Salivary amylase acts on starch Lingual lipase acts on fat Saliva Moistens food for swallowing Epiglottis; Dysphagia Esophagus Transports food to stomach Esophageal sphincter

13. 13 Swallowing and Choking

14. 14 Digestion and Absorption Stomach Hydrochloric acid Prepares protein for digestion Activates enzymes Pepsin Begins protein digestion Gastric lipase Some fat digestion Gastrin (hormone) Stimulates gastric secretion and movement

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17. 17 Digestion and Absorption Small intestine Sections of small intestine Duodenum, jejunum, ileum Digestion Bicarbonate neutralizes stomach acid Pancreatic & intestinal enzymes Carbohydrates Fat Protein

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20. 20 Digestion and Absorption Small intestine Absorption Folds, villi, microvilli expand absorptive surface Most nutrients absorbed here Fat-soluble nutrients go into lymph Other nutrients into blood

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23. 23 Digestion and Absorption Large Intestine Digestion Nutrient digestion already complete Some digestion of fiber by bacteria Absorption Water Sodium, potassium, chloride Vitamin K (produced by bacteria) Elimination

24. 24 Circulation of Nutrients Vascular system Lymphatic system Excretion and elimination

25. 25 Signaling Systems: Command, Control, Defense Nervous system Regulates GI activity Local system of nerves Central nervous system Hormonal system Increases or decreases GI activity Immune system Identifies and attacks foreign invaders

26. 26 Nutrition and GI Disorders Constipation Hard, dry, infrequent stools Reduced by high fiber, fluid intake, exercise Diarrhea Loose, watery, frequent stools Symptom of diseases/infections Can cause dehydration Diverticulosis Pouches along colon High fiber diet reduces formation

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28. 28 Nutrition and GI Disorders Gastroesophageal Reflux Disease (GERD) Reduced by smaller meals, less fat Irritable Bowel Syndrome (IBS) Colon cancer Antioxidants may reduce risk Gas Ulcers Bacterial cause; helicobacter pylori Functional dyspepsia

29. 29 1. Name three types of absorption. How are they different from each other? 2. What is the difference between peristalsis, segmentation, & sphincter? 3. Describe enterohepatic circulation. 4. Name the 3 parts of the small intestine. What happens in each part? 5. Joe has constipation. What would you recommend to help him? How can chronic constipation hurt the colon? 6. Tara has GERD. What is this and what would you recommend?

30. 30 Carbohydrates Sugars, Starches, Fibers Major food sources: plants Formed during photosynthesis

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32. 32 Chapter Objectives Understand simple vs. complex carbs Explain the process of carb digestion and absorption Describe how BG levels are affected by carb consumption Understand how to increase complex carb intake and decrease sugar intake Explain how carbs affect health

33. 33 Simple Sugars:Mono and Disaccharides Monosaccharides � single sugar unit Glucose Found in fruits, vegetables, honey �blood sugar� � used for energy Fructose �fruit sugar� Found in fruits, honey, corn syrup Galactose Found as part of lactose in milk

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36. 36 Disaccharides � two linked sugar units Sucrose: glucose + fructose �table sugar� Made from sugar cane and sugar beets Lactose: glucose + galactose �milk sugar� Found in milk and dairy products Maltose: glucose + glucose Found in germinating cereal grains Product of starch breakdown

37. 37 Complex Carbohydrates Chains of more than two sugar molecules Oligosaccharides contain 3-10 sugar molecules Polysaccharides contain 100�s or 1000�s of monosaccharide units starch-digestible fiber-indigestible

38. 38 Complex Carbohydrates Starch Long chains of glucose units Amylose � straight chains Amylopectin � branched chains; Resistant starch-not digested Found in grains, vegetables, legumes Glycogen Highly branched chains of glucose units Body�s storage form of carbohydrate

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40. 40 Complex Carbohydrates Dietary Fiber Indigestible chains of monosaccharides Oligosaccharides: short chains (3-10) Non-starch polysaccharides: long chains Cellulose, hemicellulose, pectins, gums, mucilages Other: Lignins, cutins, waxes Found in fruits, vegetables, grains, legumes

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42. 42 Fiber Oligosaccharides dried beans, peas, lentils rafinose (gal-glu-fru) stachyose (gal-gal-gal-fru) metabolized by intestinal bacteria gaseous effects Cellulose makes walls of cells strong and rigid

43. 43 Hemicelluloses mixed with cellulose in cell walls outer bran layer Pectins gel forming; in fruit Gums and Mucilages thick, gel-forming used by food industry to thicken, stabilize, Lignins not a carb; indigestible substances that make up woody parts of veg; and fruit seeds

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45. 45 Carbohydrate Digestion and Absorption Mouth Salivary amylase begins digestion of starch Small intestine Pancreatic amylase completes starch digestion Brush border enzymes digest disaccharides End products of carbohydrate digestion Glucose, fructose, galactose Absorbed into bloodstream Fibers are not digested, excreted in feces

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50. 50 Functions of Carbohydrates Energy source Glucose is the body�s main fuel Adequate glucose spares protein Adequate glucose prevents ketosis Allows for complete fat breakdown Excess glucose is stored as glycogen Stored in liver and muscle

51. 51 Regulating blood glucose

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53. 53 Diabetes Diabetes Mellitus Persistent high blood glucose levels Complications of high BG Type 1: lack of insulin production Treat with insulin Type 2: cells are resistant to insulin Treat with diet and exercise May treat with oral medications May treat with insulin

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55. 55 Syndrome X Cluster of risk factors for heart disease associated with insulin resistance Hyperglycemia High Blood Pressure High Blood levels of insulin High cholesterol levels

56. 56 Carbohydrates in Your Diet Recommended carbohydrate intake 55-60% of kilocalories Daily Value (for 2,000 kcal) = 300 grams Dietary Guidelines Moderate sugar intake Variety of grains, fruits, vegetables Fiber intake of 25 grams/day

57. 57 Carbohydrates in Your Diet Increasing complex carbohydrate intake Grains, especially whole grains Legumes Vegetables

58. 58 Carbohydrates in Your Diet Reducing sugar intake Use less added sugar Limit soft drinks, sugary cereals,candy Choose fresh fruits or those cannedin water or juice

59. 59 Artificial Sweeteners Minimal or zero kcal Many times sweeter than sugar Non-cariogenic (don�t promote tooth decay) Current products --New Products Saccharin * Neotame Aspartame * D-tagatose Acesulfame * Alitame Sucralose Sugar alcohols ~2 kcal/gram Non-cariogenic

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62. 62 Aspartame Acceptable Daily Intake defined as the amount of a food additive that can be safely consumed on a daily basis over a person�s lifetime without any adverse effects. 100-fold safety factor; 50 mg/kg/body weight/day Average is 2-4 mg/kg/day 200 mg aspartame per 12-oz diet soda and 35 mg per packet

63. 63 Aspartame Intake Example 150 lbs x 2.2 = 68 kg 50 mg/kg body weight per day= 50 x 68 = 3400 mg/day is acceptable intake 6 pack of diet soda with aspartame per day 200 mg aspartame per 12 oz soda= 200 mg x 6 = 1200 mg aspartame per day phenylalanine and aspartic acid

64. 64 Carbohydrates and Health High sugar intake Low nutrient content Contributes to tooth decay If excess kcal, contributes to obesity High fiber intake Better control of blood glucose Possible reduced cancer risk Reduced risk of heart disease Healthier gastrointestinal functioning

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66. 66 Lactose Intolerance Lactose in milk and other dairy foods Lactase enzyme Symptoms Native American; African American; Chinese; Thais Alternative foods Compared to a milk allergy

67. 67 �Net Carb� �Low Carb� �Impact Carb� Total Carb calculated by subtraction of the sum of crude protein, total fat, moisture, and ash from the total weight of the food Subtract fiber g from total carb g if fiber > 5 g Count 1/2 of sugar alcohol g as carb But often subtract all sugar alcohol Glycerin= glycerol; include in total carb g and sugar alcohol g if stmt about sugars

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