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Chapter 16

Chapter 16. Food and Digestion. Section 1 Food and Energy. Objective: List and describe each of the six nutrients needed by the body. Why You Need Food. Food provides: Materials for growing Materials to repair tissues Energy The ability to maintain homeostasis. Why You Need Food.

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Chapter 16

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  1. Chapter 16 Food and Digestion

  2. Section 1Food and Energy • Objective: • List and describe each of the six nutrients needed by the body

  3. Why You Need Food • Food provides: • Materials for growing • Materials to repair tissues • Energy • The ability to maintain homeostasis

  4. Why You Need Food • Food is converted into nutrients • Nutrients = the substances in food that provide the raw materials and energy the body needs to carry out all the essential processes

  5. Why You Need Food • 6 necessary nutrients; • Carbohydrates • Fats • Proteins • Vitamins • Minerals • water

  6. Why You Need Food • The amount of energy needed to raise the temperature of one gram of water by one oC = calorie (lowercase c) • The measure of the amount of energy in food = Calorie (capital C) • 1 C = 1,000 c

  7. Carbohydrates • Major energy source • Provide raw materials to make cell parts • 2 groups: • Simple carbohydrates • Complex carbohydrates

  8. Aka sugars Naturally found in: Fruits Milk Some vegetables The major source of energy = glucose Simple Carbohydrates

  9. Complex Carbohydrates • Many sugar molecules linked in a long chain • Ex: starch • Found in potatoes, rice, corn, pasta, cereals, and bread • The long chains must be broken to get energy from the sugar molecules

  10. Complex Carbohydrates • Fiber: • Complex carbohydrate found in plants • Cannot be broken down • Not considered a nutrient • Keeps your digestive system working properly

  11. Complex Carbohydrates • 50% - 60% of your daily Calories should come from carbohydrates • Complex carbohydrates are recommended because they provide a more even, long-term energy source

  12. Fats • High-energy nutrient • Make up part of cell structures • Fatty tissue protects and supports internal organs • Insulates your body to keep heat inside your body • HOWEVER; has twice as much energy as the same amount of carbohydrates! • 2 groups: • Unsaturated fats • Saturated fats

  13. Fats • Unsaturated Fats: • Liquid at room temperature • Cooking oils • Saturated Fats • Solid at room temperature • Meat, dairy, egg yolk

  14. Fats • Cholesterol • Waxy, fatlike substance found only in animal products • Your liver makes all the cholesterol your body needs • Cholesterol is not necessary in your diet • < 30% of your diet should come from fats

  15. Proteins • Needed for tissue growth and repair • Play a part in chemical reactions in cells (enzymes) • Energy source (less than carbs & fats) • Found in meat, poultry, fish, dairy products, nuts, beans, lentils • ~12% of your diet should come from protein

  16. Proteins • The building blocks of proteins = amino acids • Only 20 different amino acids • Half of the amino acids you need can be made by your body • The others must come from your diet = essential amino acids

  17. Proteins • Complete proteins: • Contain all the essential amino acids • Sources: meat, eggs • Incomplete proteins: • Missing 1 or more essential amino acids • Sources: beans, grains, nuts

  18. Vitamins • Helper molecules in a variety of chemical reactions within the body = vitamins • If you eat a wide variety of foods, you will probably get enough of each vitamin

  19. Minerals • Nutrients not made by living things = minerals • Source: plant foods, or eating animals that eat plants • Ex: • Calcium for strong bones • Iron for red blood cells

  20. Water • Chemical reactions take place in water • Makes up most of the body’s fluids • Nutrients dissolve in water to be carried throughout your body

  21. Section 2:The Digestive Process Begins • Objectives: • Describe the general functions carried out by the digestive system and the specific functions of the mouth, esophagus, and stomach

  22. Functions of the Digestive System • 3 main functions: • Breaks food down into molecules the body can use • The molecules get carried throughout the body by the blood • Eliminates wastes from the body

  23. Functions of the Digestive System • The process by which your body breaks down food into small nutrient molecules = digestion • Mechanical digestion = food is broken into smaller pieces • Chemical digestion = chemicals break food into their smaller chemical building blocks • The process by which nutrient molecules pass through the wall of your digestive system and into your blood = absorption

  24. The Mouth • The fluid released when your mouth waters = saliva • Both mechanical and chemical digestion begin in the mouth • Teeth grind food • Enzymes in saliva begin breaking down food

  25. The Esophagus • The muscular tube that connects the mouth and the stomach = esophagus • Flap of tissue that prevents food from entering the windpipe = epiglottis • A thick, slippery substance that makes food easier to swallow and move through the esophagus = mucus • Muscle contractions that push food toward the stomach = peristalsis

  26. The Stomach • Expands to hold all the food you swallow • Mechanical and chemical digestion occur here • Has an enzyme that breaks down protein = pepsin • And a very strong acid = hydrochloric acid

  27. ASSIGNMENT • Section Review Questions • Pg. 523 • #’s 1-4 • WRITE QUESTIONS AND ANSWERS

  28. Section 3: Final Digestion and Absorption • Objectives: • To explain the role of the small intestine in digestion • To explain the role of the large intestine in digestion

  29. The Small Intestine • Almost all chemical digestion and absorption takes place in the small intestine

  30. The Role of the Liver • Breaks down medicines and other substances • Removes nitrogen from the body • Produces bile • Substance that breaks up fat particles = bile • Gallbladder- stores bile • Bile leaves gallbladder and enters small intestine after you eat

  31. Help From the Pancreas • Lies between stomach and small intestine • Produces enzymes that break down starches, proteins, and fats

  32. Absorption in the Small Intestine • Villi = tiny finger-shaped structures • The villi absorb nutrients • Nutrients then enter blood vessels

  33. The Large Intestine • The Last section of the digestive system • Contain bacteria the feed on passing material • As material moves through the large intestine, water is absorbed into the bloodstream • The remaining material is readied for elimination

  34. ASSIGNMENT • Section Review Questions • Pg. 529 • #’s 1-3 • WRITE QUESTIONS AND ANSWERS!

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