Food and Digestion

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Chapter 16

• Food and Digestion

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Section 1Food and Energy

• Objective
• List and describe each of the six nutrients
  needed by the body

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Why You Need Food

• Food provides
• Materials for growing
• Materials to repair tissues
• Energy
• The ability to maintain homeostasis

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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

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Why You Need Food

• 6 necessary nutrients
• Carbohydrates
• Fats
• Proteins
• Vitamins
• Minerals
• water

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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

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Carbohydrates

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

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Simple Carbohydrates

• Aka sugars
• Naturally found in
• Fruits
• Milk
• Some vegetables
• The major source of energy glucose

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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

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Complex Carbohydrates

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

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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

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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

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Fats

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

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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
• lt 30 of your diet should come from fats

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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

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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

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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

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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

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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

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Water

• Chemical reactions take place in water
• Makes up most of the bodys fluids
• Nutrients dissolve in water to be carried
  throughout your body

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Section 2The Digestive Process Begins

• Objectives
• Describe the general functions carried out by the
  digestive system and the specific functions of
  the mouth, esophagus, and stomach

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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

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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

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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

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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

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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

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ASSIGNMENT

• Section Review Questions
• Pg. 523
• s 1-4
• WRITE QUESTIONS AND ANSWERS

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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

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The Small Intestine

• Almost all chemical digestion and absorption
  takes place in the small intestine

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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

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Help From the Pancreas

• Lies between stomach and small intestine
• Produces enzymes that break down starches,
  proteins, and fats

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Absorption in the Small Intestine

• Villi tiny finger-shaped structures
• The villi absorb nutrients
• Nutrients then enter blood vessels

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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

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ASSIGNMENT

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