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CH 3: The Human Body; A Nutrition Perspective

CH 3: The Human Body; A Nutrition Perspective. Chapter Overview. This chapter covers everything from cell structure to all of the systems of the body! This is the content of BIO 100 in one chapter!

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CH 3: The Human Body; A Nutrition Perspective

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  1. CH 3: The Human Body; A Nutrition Perspective

  2. Chapter Overview • This chapter covers everything from cell structure to all of the systems of the body! • This is the content of BIO 100 in one chapter! • We will focus on the digestive system and systems that directly relate to the function of this system..

  3. Sections Covered • While we may touch on content in other sections, we will focus on: • Cardiovascular & lymphatic system (3.4) • Endocrine system (3.6) • Digestive system (3.8)

  4. Cardiovascular & Lymphatic Systems • CV and lymphatic system circulate fluids in the body • CV system • Heart and blood vessels • Lympahtic system • Lympahtic vessels and lymph nodes

  5. Components of Blood • Plasma – fluid portion of blood • Water soluble nutrients are dissolved in the plasma • Red blood cells • White blood cells • Platelets • Proteins • Lipoproteins • Fat soluble nutrients attach to water soluble proteins and form lipoproteins

  6. CV System & Digestive Tract, page 90 • Water soluble nutrients are absorbed in to capillaries in the small intestine (SI) (6) • Capillaries merge to form the portal vein which transports nutrients to the liver (7) • CV system then transports nutrients to the cells of the body

  7. Lymphatic System • Circulatory system made of lymph vessels and nodes • Lymph vessels transport: • white blood cells • excess fluid between cells • fat soluble nutrients absorbed from the SI • Fat soluble nutrients are absorbed in to smallest lymph vessels, called lacteals

  8. Lymphatic System • Lymph vessels leaving the SI merge with veins near the heart • Fat soluble nutrients in the lymph enter the blood, go through the heart and lungs and are then circulated in the blood

  9. Endocrine System • Endocrine glands secrete hormones • Hormones enter the blood and bind to cells with receptors for the hormone • Binding triggers a change in the target cells/organ • See table 3-2 on page 93

  10. Endocrine System

  11. Digestive System (finally) • Functions: Digestion, Absorption, Elimination • Digestion – process of breaking down foods to release nutrients • Goal is to break nutrients into absorbable units • 2 types of digestions: • Mechanical • Chemical(enzymatic)

  12. Overview Digestive System • Absorption – movement of nutrients out of GI tract into blood or lymph • Water soluble nutrients  • Fat soluble nutrients  • Excretion – elimination of undigested foods (feces)

  13. Overview Digestive System • Structure Gastrointestinal (GI) Tract • Continuous tube from mouth to anus • See board and page 97 • Accessory organs - food does not pass through these organs • Liver • Gall bladder • Pancreas

  14. GI Tract Anatomy

  15. Digestive Tract • Layers of GI tract organs • Serosa (outermost) • Interface between GI tract and lymph & blood • Muscle Layers • Longitudinal muscles • Circular muscles • Submucosal and Mucosal and layers (innermost) • Nerves, blood and lymph vessels • Cells of the mucosal layer produce secretions

  16. Mouth • Structure – teeth, tongue with taste buds, salivary glands • Secretions • Mucos • Saliva • Salivary amylase • Digestion • Mechanical …. • Enzymatic/chemical …. • Swallow  tongue pushes food  pharynx  ……

  17. Esophagus • Structure – 12” tube with sphincters • UES and LES • Function • Transports food from mouth to stomach • Peristalsis and gravity aid food movement • Secretions -- mucus • Digestion • Mechanical (limited) • Enzymatic/chemical – starch digestion continues

  18. Stomach • Structure ….page 101 • Secretions ….. • Digestion …… • Mechanical • Enzymatic/chemical

  19. Stomach • Structure – muscular sack that can expand • extra muscle layer to aid in the mechanical digestion of food (pg 101)

  20. Stomach Related Secretions • Gastrin • hormone that stimulates stomach to release secretions • Hydrochloric Acid (HCl) • unravels proteins • kills bacteria • activates the enzyme pepsinogen • Makes minerals soluble • Pepsinogen • once activated, begins protein digestion

  21. Stomach Related Secretions • Mucus • secreted by goblet cells • protects stomach • Moistens/lubricates food mass = chyme • Intrinsic factor (IF) • Binds vitamin B-12 • Required for B-12 to be absorbed in SI

  22. Stomach - Digestion • Mechanical • Stomach muscles grind food into a paste called chyme • Enzymatic/chemical • Proteins uncoiled • Protein digestion to polypeptides begins • Starch digestion stops (why??)

  23. Chyme leaves the stomach through the _____________ sphincter and enters the small intestines. • Small amounts of chime enter SI at a time

  24. Small Intestine (SI) • Function – The SI is where: • the majority of digestion to absorbable units occurs • Digestion of carbohydrates, fats, and proteins • Vitamins and minerals do not need digestion • Nutrients are absorbed into either capillaries or lacteals

  25. Small Intestine • Structure – see page 102 • Length – 10 feet (~ 21’-22’ long when relaxed) • Layers ….. • Mucosal folds, villi, microvilli …. • Goblet cells and crypts – create secretions • Lacteals and capillaries …. • Sections • Duodenum • Jejunum • Ileum

  26. Small Intestine

  27. The Small Intestinal Villi

  28. The Small Intestinal Villi

  29. Small Intestines • Secretions of the SI • Mucus • Secreted by ____________ cells • Digestive enzymes that finish the digestion of carbs, fats, and proteins • Secreted from crypts

  30. Secretions of the SI, cont’d 3. Hormones • Secretin • produced when chyme enters SI • stimulates pancreatic secretions • Gastric-inhibitory peptide • produced when chyme enters SI • Slows stomach secretions • Slows GI motility • Cholecystokinin - CCK • produced when fat enters SI • Stimulates _________to release ______ • Slows GI motility (slows peristalsis)

  31. Secretions into SI • Pancreatic secretions: • Released in response to ________ • Sodium bicarbonate • Neutralizes acidic chime • Digestive enzymesthat begin the digestion of carbs, fats, and proteins

  32. Secretions into SI • Liver and Gall Bladder - Bile • Liver makes bile • Gall bladder concentrates and stores bile • Bile is released into SI in response to the hormone _______ • Function of bile:

  33. SI - Digestion • Mechanical digestion • Muscle action breaks food into smaller and smaller pieces • Peristalsis pushes food through SI • Segmentation mixes chyme with digestive enzymes • Bile emulsifies fats • Chemical/Enzymatic • Pancreatic and SI enzymes digest carbs, fats, and proteins to absorbable units

  34. Peristalsis & Segmentation

  35. SI - Absorption • Absorbed into capillaries (blood) • Digested carbohydrates and proteins • Minerals • Some require helper proteins/cells on walls of SI to be absorbed • Water soluble vitamins • Blood takes nutrients to the liver for processing after absorption (pg 90)

  36. SI - Absorption • Absorbed into lacteals (lymph) • Digested fats • Fat soluble vitamins • Cholesterol • Nutrients travel through lymph system to chest area where lymph and blood join • Nutrients enter blood and travel through body

  37. SI Review What is the relationship between the structure of the SI and its function?

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