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 Red blood cells
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

8. 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

9. 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

11. 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

12. Endocrine System

13. 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)

14. 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)

15. 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

16. GI Tract Anatomy

19. 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

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

24. Esophagus Structure – 12” tube with sphincters Function
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

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

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

28. 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

29. 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

30. Stomach related secretions
Function
Gastrin
HCl
Pepsinogen
Mucus
Intrinsic Factor

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

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

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

40. Secretions of SI
When Secreted and Function
Mucus
Digestive Enzymes
Secretin
CCK
Gastric inhibitory peptide

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

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

44. Secretions into SI
Secreted by and Function
Sodium bicarbonate
Digestive Enzymes
Bile

45. SI - Digestion Mechanical digestion Chemical/Enzymatic
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

46. Peristalsis & Segmentation

47. 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)

48. 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

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

51. Large Intestine or Colon
Undigested foods (fiber) enter into colon
Unabsorbed nutrients pass into colon
E.g. calcium, iron, cholesterol trapped in fiber

52. Colon Structure Ileocecal sphincter connects colon to SI
Appendix is a little pouch near beginning of colon
Colon is ~5-6’ long, “wraps around” SI
Wider diameter than SI
No villi or microvilli
No digestive enzymes
Pages 104/105

54. Colon Secretions Mucus Bacteria living in colon
Digest small amounts of fiber and undigested nutrients
Often produce…...

55. Colon Absorption Fiber attracts water
Water, salts, vitamins made by bacteria are absorbed into __________ (answer is either capillaries or lacteals. Which one is it?..you know!)
Fiber attracts water
Too little fiber in diet 
Too much fiber in diet 

56. Rectum and Anus Feces pass from colon into rectum
Rectum stores feces until excretion occurs
Feces exit body via anus
2 anal sphincters
Internal and external anal sphincters