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The Digestive SystemThe Digestive SystemFood and EnergyFood and Energy

The Digestive SystemThe Digestive SystemFood and EnergyFood and Energy

Chapter 15-section 1Chapter 15-section 1

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Key Concepts• Why does your body need food?• How do the six nutrients needed

by the body help carry out essential processes?

• How can the Food Guide Pyramid and food labels help you have a healthy diet?

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Key TermsNutrient Calorie

Carbohydrate Glucose

Fat Protein

Amino acid Vitamin

Mineral Food guide pyramid

Percent daily value Dietary reference intakes (DRI’s)

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Why you need food• Food provides your body with materials

for growing and for repairing tissue• Food also provides energy for

everything you do– Ex-running, reading, sleeping, Food also helps your body maintain

homeostasis

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Nutrients• Your body breaks down the foods

you eat into nutrients• There are six groups of nutrients

necessary for human health– Carbohydrates, fats, proteins,

vitamins, minerals, and water

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Energy• When nutrients are used by the body for

energy, the amount of energy they release can be measured in units called calories

• Calorie with a C is used to measure the energy in foods

• You need to eat a certain number of calories each day to meet your body’s energy needs

• Your daily energy requirement depends on your level of physical activity, the more active you are the greater your energy needs are

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Carbohydrates• They are composed of carbon, oxygen,

and hydrogen and are a major source of energy

• One gram of carbohydrate provides your body with four Calories of energy

• Carbohydrates provide the raw materials to make cell parts. They are divided into simple carbohydrates and complex carbohydrates

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Simple carbohydrates• These carbohydrates are known as

sugar and provide quick energy for the body

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Complex Carbohydrates

• Complex carbohydrates are made up of many sugar molecules lined together in a chain

• Starch is a complex carbohydrate found in foods from plants such as potatoes, rice, wheat, corn

• Fiber is a complex carbohydrate but unlike starch fiber cannot be broken down into sugar molecules, instead fiber passes through the body and is eliminated

• Fiber helps keep the digestive system functioning properly

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Fats• Fats contain more than twice the

energy of an equal amount of carbohydrates

• Fats form part of the cell membrane, the structure that forms the boundary of a cell

• Fatty tissue protects and supports your internal organs and insulates your body

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Kinds of fatssaturated and unsaturated

• Unsaturated fats are usually liquid at room temperature-olive oil

• Saturated fats are usually solid at room temperature-Crisco

• Trans fats help keep food fresher longer and are considered to be less healthful than unsaturated fats

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Cholesterol • Waxy, fatlike substance found only

in animal products• Your liver can make all of the

cholesterol your body needs and is not a necessary part of the diet

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Proteins• Are needed for tissue growth and

repair• They also play an important part

in chemical reactions within cells• 10-35 percent of your daily Calorie

intake should come from proteins

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Amino Acids• Proteins are made up of small

units called amino acids which are linked together chemically to form large protein molecules

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Complete and Incomplete Proteins

• Complete proteins-meat and eggs, these foods contain all the essential amino acids

• Incomplete proteins-come from plant sources such as beans, grains and nuts. They are incomplete because they are missing one or more essential amino acid

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Vitamins and Minerals• Unlike other nutrients V & M do not

provide the body with energy or raw materials

• Instead they help the body carry out various processes

• Vitamins act as helper molecules in a variety of chemical reactions-– Ex – Vitamin K helps blood to clot

• Vitamin D can be made when your skin is exposed to sunlight

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Fat Soluble and Water Soluble Vitamins

• Fat soluble vitamins dissolve in fat and they are stored in fatty tissues in the body– Vitamins A, D, E, and K are all fat soluble

vitaminsWater-soluble vitamins dissolve in water and

are not stored in the bodyVitamins- C and D are water soluble vitamins

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Importance of Vitamins• Vitamins are only needed in small

amounts• A lack of certain vitamins in the

diet can lead to health problems

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Importance of Minerals• Minerals are present in soil and are

absorbed by plants through their roots• Minerals are obtained by eating plant

foods or animals that have eaten plants– Ex. Calcium-strong bones and teeth

• Iron is needed for the proper functioning of red blood cells

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Vitamins and Minerals• Are needed by your body in small

amounts to carry out chemical processes

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Water• Water is the most abundant

substance in the body• It accounts for 65 percent of the

average person’s body weight• People cannot survive without

fresh water

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Where do the body’s vital processes take

place?• Water• The body’s vital processes including

chemical reactions such as the break down of nutrients take place in water

• Cells in your body are mostly composed of water

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(2)• Nutrients and other important substances

are carried throughout the body dissolved in the watery part of the blood

• Water in blood also carries waste materials that must be removed from your body

• Perspiration consists of chemicals dissolved in water,comes from body tissue, and helps regulate body temperature by cooling the body

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The Food Guide Pyramid

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Food Guide Pyramid• Classifies foods into six groups• Indicates how many servings from

each group should be eaten everyday to maintain a healthy diet

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1. What are some reasons that your body

needs food?

• Feel your best, perform well in school and sports, reduce your risk of illness

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2. How are fats beneficial

• They provide energy form part of cell membranes, protect and support internal organs, insulate your body

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3. Are vitamins and minerals sources of

energy• no

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4. Why is it important to get vitamins and minerals from food?

• The body cannot make minerals and some vitamins

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5. To obtain enough calcium what foods should people eat if

they do not drink milk?

• Cheese, dark green leafy vegetables

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6. What does the body use calcium for?

• Building bones and teeth, clotting blood and nerve and muscle function

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7. How does water work with vitamins and

minerals to carry out body processes?

• Vitamins and minerals help carry out chemical reactions which take place in water

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8. Why are the food groups shaped like a

pyramid• The wider base indicates that the

greatest portion of persons diet should be from this group

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9. Name two ways in which foods are used by

the body?

• Growing, repairing tissues, providing energy, maintaining homeostasis

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10. What is a calorie?• The amount of energy needed to

raise the temperature of one gram of water by one degree Celsius, the more Calories a food has the more energy it contains