CH 3: The Human Body; A Nutrition Perspective

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. Blood • Blood is made of: • Plasma – fluid portion of blood • Water soluble nutrients are dissolved in the plasma • Red blood cells • White blood cells • Platelets • Proteins and other substances • Fat soluble nutrients are often carried by water soluble proteins

6. CV System • Heart  -> Lungs • Veins bring deoxygenated blood to the right side of the heart • Right side of the heart pumps deoxygenated blood to the lungs • Blood returns to the left side of the heart oxygenated • Left side of heart pumps blood to entire body by way of arteries

7. Blood Vessels • Blood leaves heart through an artery (aorta) • Vessels branch in to smaller and smaller vessels • Smallest blood vessel is the capillary • Exchanges of gases, nutrients and wastes between body cells and the CV system occur at the capillary level

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

10. Lymphatic System • Lymph vessels transports: • white blood cells • excess fluid between cells • Returns the fluid to the blood • fat soluble nutrients absorbed from the SI • Lymph vessels branch to form lacteals • Fat soluble nutrients are absorbed in to lacteals – page 91

11. 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

13. Endocrine System • Endocrine glands secrete hormones • Hormones enter the blood and bind to target cells • Cells with receptors for the hormone • Binding triggers a change in the target cells/organ • See table 3-2 on page 94

14. Endocrine System

15. 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)

16. 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)

17. Overview Digestive System • Structure Gastrointestinal (GI) Tract • Continuous tube from mouth to anus • See board and page 97

18. GI Tract Anatomy

20. 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

22. Mouth • Structure – teeth, tongue, salivary glands • Secretions • Saliva • Mucus • Salivary amylase • Digestion • Mechanical …. • Enzymatic/chemical …. • Swallow  tongue pushes food  pharynx  ……

25. Esophagus • Structure – 12” tube • 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

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

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

29. Stomach Related Secretions • Gastrin – hormone that stimulates stomach to release secretions • Hydrochloric Acid (HCl) -- unravels proteins, kills bacteria, activates pepsinogen • Pepsinogen – once activated, begins protein digestion

30. Stomach Related Secretions • Mucus – secreted by goblet cells, protects stomach, moistens food • Intrinsic factor (IF) – IF binds vitamin B-12 • Required for B-12 to be absorbed

32. 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??)

33. 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

34. 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

35. Small Intestine

36. The Small Intestinal Villi

37. The Small Intestinal Villi

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

39. Small Intestine • Secretions of the SI, cont’d • Hormones • Secretin … • CCK …. • Gastric-inhibitory peptide …

40. Small Intestine - Hormones • Secretin – produced when chyme enters SI • stimulates pancreatic secretions • *CCK – produced when fat enters SI • Stimulates _________to release ______ • Slows GI motility (slows peristalsis) • *Cholecystokinin • Gastric–inhibitory peptide– produced when chyme enters SI • Slows stomach secretions • Slows GI motility

42. Secretions into SI • Pancreatic secretions: • Released in response to ________ • Sodium bicarbonate • Neutralizes acidic chyme • Digestive enzymes that begin the digestion of carbs, fats, and proteins

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

46. Small Intestine • Digestion - Mechanical • Peristalsis pushes food through SI • Segmentation mixes chyme with digestive enzymes • Also breaks up food mass into smaller masses • Bile emulsifies fats

47. Peristalsis & Segmentation

48. Muscular Action of Digestion Segmentation

49. SI - Digestion • Mechanical digestion • Muscle action breaks food into smaller and smaller pieces • Bile emulsifies fats • Chemical/Enzymatic • Pancreatic and SI enzymes digest carbs, fats, and proteins to absorbable units

50. 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)