Chapter3

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Chapter3

  1. 1. Chemical, Biological, and Physiological Aspects of Nutrition Chapter 3
  2. 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. 3. Levels of Organization in the Body
  4. 4. How Does Chemistry Apply to the Study of Nutrition? • Atoms • Protons • Neutrons • Electrons • Ions • Cations • Anions • Important ions
  5. 5. Formation of Cations and Anions
  6. 6. How Does Chemistry Apply to the Study of Nutrition? • Reduction-oxidation (redox) reactions • Oxidation • Loss of electrons • Reduction • Gain of electrons
  7. 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. 8. The Most Abundant Elements in the Human Body
  9. 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. 10. Condensation and Hydrolysis
  11. 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. 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. 13. Passive Transport
  14. 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. 15. Active Transport
  16. 16. A Typical Cell
  17. 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. 18. Four Basic Types of Tissue
  19. 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. 20. Organ Systems and Related Major Functions
  21. 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. 22. Organs of the Digestive System
  23. 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. 24. The Layers of the GI Tract
  25. 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. 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. 27. Sphincters Regulate the Flow of Food
  28. 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. 29. Segmentation
  30. 30. Peristalsis
  31. 31. How Do Gastrointestinal Motility and Secretions Facilitate Digestion? • GI secretions • Mucus • Protective coating • Digestive enzymes • Biological catalysts • Organs that release digestive secretions
  32. 32. Summary of Major GI Secretions
  33. 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. 34. The Major GI Hormones & Their Related Functions
  35. 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. 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. 37. Voluntary & Involuntary Phases of Swallowing
  38. 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. 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. 40. Anatomy of the Stomach and Its Role in Digestion
  41. 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. 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. 43. Peptic Ulcers
  44. 44. Gastroesophageal Reflux Disease (GERD)
  45. 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. 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. 47. Overview of the SI and Accessory Organs
  48. 48. Absorptive Surface of the Small Intestine
  49. 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. 50. The Pancreas
  51. 51. The Role of the Liver and Gallbladder in Digestion
  52. 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. 53. Nutrient Absorption and Circulation
  54. 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. 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. 56. Nutrient and Gas Exchange across the Capillary Wall
  57. 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. 58. Systemic and Pulmonary Circulation
  59. 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. 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. 61. Overview of the Urinary System
  62. 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. 63. Overview of the Large Intestine
  64. 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. 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. 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. 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

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