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Chapter3

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  • 1. Chemical, Biological, and Physiological Aspects of Nutrition Chapter 3
  • 2. How Does Chemistry Apply to the Study of Nutrition? • Organization • Atoms → simple molecules → complex molecules → cells → tissues → organs → organ systems • Made of and fueled by nutrients in food
  • 3. Levels of Organization in the Body
  • 4. How Does Chemistry Apply to the Study of Nutrition? • Atoms • Protons • Neutrons • Electrons • Ions • Cations • Anions • Important ions
  • 5. Formation of Cations and Anions
  • 6. How Does Chemistry Apply to the Study of Nutrition? • Reduction-oxidation (redox) reactions • Oxidation • Loss of electrons • Reduction • Gain of electrons
  • 7. How Does Chemistry Apply to the Study of Nutrition? • Simple molecules • Elements – 20 essential for human health • 6 elements account or 99% of total body weight • Chemical bonds • Compounds • Molecular formulas
  • 8. The Most Abundant Elements in the Human Body
  • 9. How Does Chemistry Apply to the Study of Nutrition? • Complex molecules • Examples • Assembly and disassembly • Condensation • Hydrolysis • Acid-base chemistry • pH scale – Basic, neutral, acidic – Buffers
  • 10. Condensation and Hydrolysis
  • 11. How Do Biological Molecules Form Cells, Tissues, Organs, & Organ Systems? • Cells • Organelles, cytoplasm, Extracellular and intracellular environments • Cell membranes • Selectively permeable • Transport mechanisms – Passive transport mechanisms – Active transport mechanisms
  • 12. How Do Biological Molecules Form Cells, Tissues, Organs, & Organ Systems? • Passive transport mechanisms • Simple diffusion • Facilitated diffusion • Membrane-bound transport proteins • Osmosis • Solutes
  • 13. Passive Transport
  • 14. How Do Biological Molecules Form Cells, Tissues, Organs, & Organ Systems? • Active transport mechanisms • Carrier-mediated active transport • Requires ATP & transport proteins • Vesicular active transport • Endocytosis • Exocytosis Carrier-mediated active transport
  • 15. Active Transport
  • 16. A Typical Cell
  • 17. How Do Biological Molecules Form Cells, Tissues, Organs, & Organ Systems? • 4 types of tissues, 40 organs, 11 unique organ systems • Tissues • Epithelial • Connective • Muscle • Smooth, cardiac, skeletal • Neural
  • 18. Four Basic Types of Tissue
  • 19. How Do Biological Molecules Form Cells, Tissues, Organs, & Organ Systems? • Organs • Two or more different types of tissues • Organ system • Communication systems • Nervous system – Neurotransmitters • Endocrine system – Hormones • Negative feedback systems
  • 20. Organ Systems and Related Major Functions
  • 21. How Does the Digestive System Break Down Food into Absorbable Components? • Gastrointestinal tract • Hollow tube from mouth to anus • Organs • Mouth, esophagus, stomach, small intestine, and large intestine • Accessory organs • Three important functions • Digestion, absorption, and egestion
  • 22. Organs of the Digestive System
  • 23. How Does the Digestive System Break Down Food into Absorbable Components? • Tissue layers • Mucosa • Mainly epithelial cells • GI secretions • Lifespan • Submucosa • Rich supply of blood vessels • Lymphatic vessels • Network of nerves
  • 24. The Layers of the GI Tract
  • 25. How Does the Digestive System Break Down Food into Absorbable Components? • Tissue layers • Muscularis • Two layers of smooth muscle – Longitudinal layer and circular layer • Mixing of food mass with digestive secretions • Serosa • Secretes fluid that lubricates digestive organs
  • 26. How Do Gastrointestinal Motility and Secretions Facilitate Digestion? • Transit time • 24 to 72 hours • Factors affecting transit time • Sphincters • Named according to anatomical locations
  • 27. Sphincters Regulate the Flow of Food
  • 28. How Do Gastrointestinal Motility and Secretions Facilitate Digestion? • GI motility • Mixing and propulsion of material • Muscular contractions • Two types of movement • Segmentation – Mixes and propels food • Peristalsis – Vigorous propulsive movements
  • 29. Segmentation
  • 30. Peristalsis
  • 31. How Do Gastrointestinal Motility and Secretions Facilitate Digestion? • GI secretions • Mucus • Protective coating • Digestive enzymes • Biological catalysts • Organs that release digestive secretions
  • 32. Summary of Major GI Secretions
  • 33. How Do Gastrointestinal Motility and Secretions Facilitate Digestion? • Three regulatory control mechanisms • Neural • Enteric nervous system – Sensory receptors: chemoreceptors & mechanoreceptors • Central nervous system • Hormonal • GI hormones – Influence desire to eat
  • 34. The Major GI Hormones & Their Related Functions
  • 35. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Three phases of digestion • Cephalic phase • Before food enters mouth • Gastric phase • Arrival of food in stomach • Intestinal phase
  • 36. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Digestion begins in the mouth • Mastication • Saliva • Taste sensation • Salty, sour, sweet, bitter, umami • Olfactory and gustatory cells • Swallowing • Phases • Bolus
  • 37. Voluntary & Involuntary Phases of Swallowing
  • 38. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Esophagus • • • • Delivers food to the stomach Dysphagia Gastroesophageal sphincter Transit time • Less than 10 seconds
  • 39. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Stomach • Regions • Fundus, body, and antrum • Pyloric sphincter • Storage • Rugae • Mixing food with gastric secretions • Third layer of smooth muscle • Chyme
  • 40. Anatomy of the Stomach and Its Role in Digestion
  • 41. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Stomach • Gastric secretions • Gastric pits – Endocrine and exocrine cells • Gastrin • Parietal cells • Chief cells • Gastric mucosal barrier
  • 42. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Stomach • Peptic ulcers • Types • Helicobacter pylori (H. pylori) • Symptoms • Gastroesophageal reflux disease (GERD) • Gastroesophageal sphincter • Symptoms • Diagnosis
  • 43. Peptic Ulcers
  • 44. Gastroesophageal Reflux Disease (GERD)
  • 45. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Regulation of gastric emptying • Influential factors • Volume • Consistency • Composition of chyme • Influence of small intestine • Cholecystokinin (CCK)
  • 46. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Small intestine • Chemical digestion and nutrient absorption • Regions • Duodenum, jejunum, and ileum • Lining of small intestine • Plica circulares • Villi – Enterocytes • Microvilli • Lacteal
  • 47. Overview of the SI and Accessory Organs
  • 48. Absorptive Surface of the Small Intestine
  • 49. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Digestion in the small intestine • Regulated by hormones • Secretin and CCK • Pancreatic juice • Bile • Produced in liver; stored in gallbladder • Digestion of fatty foods • Enterohepatic circulation • Enzyme facilitation
  • 50. The Pancreas
  • 51. The Role of the Liver and Gallbladder in Digestion
  • 52. How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? • Nutrient absorption • Passive and active transport mechanisms • Stomach absorption • Small intestine absorption • Entry into and exit from enterocyte • Bioavailability • Influential factors
  • 53. Nutrient Absorption and Circulation
  • 54. How Does the Body Circulate Nutrients & Eliminate Cellular Waste Products? • Transport • Circulatory system • Absorption from small intestine • Water-soluble nutrients • Circulate to liver in bloodstream
  • 55. How Does the Body Circulate Nutrients & Eliminate Cellular Waste Products? • Cardiovascular system • Two loops • Systemic circulation • Delivers blood to all the body’s organs except lungs • Capillaries • Exchange of materials, nutrients, and gases • Arterial and venous vascular systems • Similarities and differences
  • 56. Nutrient and Gas Exchange across the Capillary Wall
  • 57. How Does the Body Circulate Nutrients & Eliminate Cellular Waste Products? • Cardiovascular system • Pulmonary circulation • Circulation between the heart and lungs • Pulmonary arteries and veins
  • 58. Systemic and Pulmonary Circulation
  • 59. How Does the Body Circulate Nutrients & Eliminate Cellular Waste Products? • Lymphatic system • Circulates fat-soluble nutrients • Eventually delivers them to cardiovascular system • Route initially bypasses the liver
  • 60. How Does the Body Circulate Nutrients & Eliminate Cellular Waste Products? • Kidneys • Cellular waste products • Nephrons • Filtration – Initially removes substances from the blood • Reabsorption • Causes of impaired kidney function • Hemodialysis • Formation of urine
  • 61. Overview of the Urinary System
  • 62. What Is the Role of the Large Intestine? • Major functions • Absorption and reabsorption • Microbial action • Storage and elimination • Four general regions • Cecum • Colon • Rectum • Anal canal
  • 63. Overview of the Large Intestine
  • 64. What Is the Role of the Large Intestine? • Cecum • Appendix • Ileocecal sphincter • Colon • Ascending, transverse, descending • Anal canal • Internal and external anal sphincters
  • 65. What Is the Role of the Large Intestine? • Absorption and reabsorption • Haustral contractions • Absorption • Some water and electrolytes • Reabsorption • GI secretions • Feces • Diarrhea and constipation
  • 66. What Is the Role of the Large Intestine? • Microbial action • Intestinal microbiota • More than 400 species • Important roles • Probiotic and prebiotic foods • Egestion • Defecate
  • 67. Irritable Bowel Syndrome & Inflammatory Bowel Disease • Inflammatory bowel disease (IBD) • Autoimmune disease • Examples • Ulcerative colitis • Crohn’s disease • Irritable bowel syndrome (IBS) • Functional disorder • Underlying cause has not been determined