Chapter 3 The Remarkable Body

1. Chapter 3The 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 • 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 • Body fluids • 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 • 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 • 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 • 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 • 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 • 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 • Glycogen • Fat cells – fat and fat-related substances • Variations in nutrient stores