Chapter Introduction

Lesson 1 Nutrition

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How do the digestive and excretory systems help maintain the body’s homeostasis?

What do you think?

Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements.

1. An activity such as sleeping does not require energy.

2. All fats in food should be avoided.

3. Digestion begins in the mouth.

Do you agree or disagree?

4. Energy from food stays in the digestive system.

5. Several human body systems work together to eliminate wastes.

6. Blood contains waste products that must be removed from the body.

Do you agree or disagree?

• Why do you eat?

• Why does your body need each of the six groups of nutrients?

• Why is eating a balanced diet important?

Nutrition

• Calorie

• protein

• carbohydrate

• fat

Nutrition

• vitamin

• mineral

• A Calorie (Cal) is the amount of energy it takes to raise the temperature of 1 kg of water by 1°C.

• All foods give your body energy to use.

• The amount of energy in food is measured in Calories.

Why do you eat?

• The amount of energy a person needs depends on factors including weight, age, activity level, and gender.

Why do you eat? (cont.)

• Food is made of nutrients—substances that provide energy and materials for cell development, growth, and repair.

Why do you eat? (cont.)

Why do you eat?

• The six groups of nutrients are proteins, carbohydrates, fats, vitamins, minerals, and water.

• Each nutrient has a different function in the body, and they are all needed for homeostasis.

• A protein is a large molecule that is made of amino acids and contains carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.

Groups of Nutrients

Combinations of 20 different amino acids make up the proteins in the body.

Groups of Nutrients (cont.)

protein

from Greek proteios, means “the first quality”

Proteins relay signals between cells, protect against disease, provide support to cells, and speed up chemical reactions.

Groups of Nutrients (cont.)

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• Carbohydrates are molecules made of carbon, hydrogen, and oxygen atoms and are usually the body’s major source of energy.

• Carbohydrates are commonly starches, sugars, or fibers.

• Fats, or lipids, provide energy and help your body absorb vitamins.

Groups of Nutrients (cont.)

• Fats are a major part of the cell membrane and help insulate the body against cold temperatures.

• Fats are often classified as either saturated or unsaturated.

• A diet high in saturated fats can increase levels of cholesterol, which can increase the risk of heart disease.

Groups of Nutrients (cont.)

• Vitamins are nutrients that are needed in small amounts for growth, regulating body functions, and preventing some disease.

• Minerals are inorganic nutrients—nutrients that do not contain carbon—which help the body regulate many chemical reactions.

Groups of Nutrients (cont.)

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• Your body needs water for chemical reactions to occur.

• Your body takes in water when you eat or drink and loses water when you sweat, urinate, and breathe.

• When lost water is not replaced, you can become dehydrated.

Groups of Nutrients (cont.)

Groups of Nutrients (cont.)

Why does your body need nutrients?

• Nutritious foods come from the major food groups, which include grains, vegetables, fruits, oils, milk products, and meats and beans.

• A healthful diet includes carbohydrates, proteins, fats, vitamins, minerals, and water.

Healthy Eating

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Healthy Eating (cont.)

Why is eating a balanced diet important?

Food labels help you determine the amount of protein, carbohydrates, fats, and other substances in food.

Healthy Eating (cont.)

• People eat food to obtain the energy their bodies need to function.

• Proteins are one of the six groups of nutrients.

• Evaluating food labels can help you eat a balanced diet.

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A. protein

B. Calorie

C. fat

D. vitamin

Which term describes the amount of energy it takes to raise the temperature of 1 kg of water by 1°C?

A. proteins C. lipids

B. carbohydrates D. vitamins

Which of these describes a molecule made of carbon, hydrogen, and oxygen atoms that functions as a major source of energy?

A. carbohydrates

B. proteins

C. sugar molecules

D. nutrients

Which of these are large molecules made of amino acids?

1. An activity such as sleeping does not require energy.

2. All fats in food should be avoided.

Do you agree or disagree?

• What does the digestive system do?

• How do the parts of the digestive system work together?

• How does the digestive system interact with other systems?

The Digestive System

• digestion

• mechanical digestion

• chemical digestion

The Digestive System

• enzyme

• esophagus

• peristalsis

• chyme

• villi