1. Chapter 3 The Remarkable Body
Nutrition: Concepts & Controversies, 12e Sizer/Whitney

2. Learning Objectives
Describe the levels of organization in the body, and identify some basic ways in which nutrition supports them.
Compare the terms mechanical digestion and chemical digestion, and point out where these processes occur along the digestive tract.
Trace the breakdown and absorption of carbohydrate, fat, and protein from the mouth to the colon.

3. The Body’s Cells Body is composed of trillions of cells
Body needs nutrients
Cells are self-contained, living entities
Depend on one another
Basic needs
Essential nutrients
Cells die at varying rates

4. A Cell (Simplified Diagram)

5. The Body’s Cells Genes Tissues, organs, and body systems
Control function
Direct production of proteins
Provide instruction for structural components of cells
Affects how body handles nutrients
Complete set of genes in each cell
Tissues, organs, and body systems

6. From DNA to Living Cells

7. The Body Fluids and the Cardiovascular System
Supply energy, oxygen, nutrients, and water
Deliver fresh supplies and pick up wastes
Types of fluids
Blood
Arteries, veins, capillaries
Plasma
Lymph

8. Blood Flow in the Cardiovascular System

9. The Body Fluids and the Cardiovascular System
Extracellular fluid
Intracellular fluid
All cell reactions take place
Holds cellular shape

10. The Body Fluids and the Cardiovascular System
All blood circulates to the lungs
Picks up oxygen
Releases carbon dioxide

11. The Body Fluids and the Cardiovascular System
Blood returns to heart
Blood pumped to rest of body
Delivers nutrients
Picks up wastes
Blood passes through digestive system
Picks up nutrients
Except for fats
Fats travel via lymph
Routed directly to liver

12. Lymph Vessels and the Bloodstream

13. The Body Fluids and the Cardiovascular System
Kidneys
Fluid intake
Red blood cell life expectancy
Blood is sensitive to malnutrition

14. The Hormonal and Nervous System
Hormones
Chemical messengers
Secreted and released directly into blood by glands
Stimulate organs to take action
Glands monitor conditions in the body
Pancreas
Insulin and glucagon

15. The Hormonal and Nervous System
Nutrition affects the hormonal system
Hormones affect nutrition
Appetite changes during pregnancy
Nervous system
Receives and integrates information from sensory receptors
Role in hunger regulation
Cortex and hypothalamus

16. Cutaway Side View of the Brain Showing the Hypothalamus & Cortex

17. The Hormonal and Nervous System
Fight-or-flight reaction (stress response)
Neurotransmitters
Epinephrine and norepinephrine
Metabolism speeds up
Organ response
Eyes, heart, liver, stomach
Heart disease

18. The Immune System Cooperation among tissues to maintain defenses
Physical barriers
Antigen
Immune defenses
White blood cells
Phagocytes
Lymphocytes (T-cells and B-cells)

19. The Immune System Inflammation Response to injury or irritation
Increased white blood cells, redness, heat, pain, swelling
Normal and healthy response
Problem with chronic inflammation
Dietary factors

20. The Digestive System Four basic chemical tastes
Sweet, sour, bitter, and salty
Savory
Sweet, salty, and fatty foods
Almost universally desired
Can lead to drastic overeating of these substances

21. The Digestive System Digestive tract
Flexible, muscular tube
Path
Total length of about 26 feet
Body surrounds digestive canal
System’s job is to digest food to its components, absorb, and excrete
System works at two levels

22. The Digestive System

23. The Digestive System Chemical digestion Digestive juices Mouth Stomach
Salivary glands, stomach, pancreas, liver, and small intestine
Mouth
Saliva – starches and fat
Saliva – health of teeth
Stomach
Hydrochloric acid – protein

24. The Digestive System Chemical digestion
Intestine
Bile
Pancreatic juice
Digestive enzymes in wall of intestine
Fiber
Food combinations and digestion

25. The Digestive System Within 24 to 48 hours Mouth
90% of carbs, fat, and protein are digested and absorbed
Mouth
Food is crushed, mashed, and mixed with saliva
Carbohydrate digestion begins
Swallowing
Peristalic waves

26. The Digestive System Stomach Small intestine Large intestine
Gastric juice mixes with food
Unwinds proteins
Chyme
Small intestine
Bile from the liver
Pancreas
Large intestine

27. The Digestive System

28. The Digestive System Absorption
Nutrient molecules transverse intestinal lining
Water-soluble components
Fat-soluble components
Cells of small intestine are selective
Folded structure
Villi
Microvilli

29. Details of the Small Intestine Lining

30. The Digestive System Transport Nourishment of digestive tract
Lymph vessels
Products of fat digestion
Fat-soluble vitamins
Blood vessels
Products of carbohydrate & protein digestion
Most vitamins
Minerals
Nourishment of digestive tract

31. The Excretory System Organs involved in waste removal Kidneys
Lungs, liver, kidneys
Kidneys
Waste materials are dissolved in water
Working units – nephrons
Urine is stored in bladder
Sodium and blood pressure
Work regulated by hormones
Importance of water supply

32. Storage Systems Eating intervals of 4-6 hours Major storage sites
Liver – carbohydrates
Glycogen
Muscles – carbohydrates
Fat cells – fat and fat-related substances
Variations in nutrient stores