Chapter 6: Nutrition
6.1 Why Your Body Needs Food
∙ Food contains many substances that provide one with energy as well as the materials needed for their body to grow and repair itlf
Your Body – What is it Made of?-父子证明
∙ Made of matter
∙ The human body is mostly hydrogen, oxygen, carbon and nitrogen (96% of one’s total mass)
蓝猫西行记∙ Phosphorus, iron, iodine, etc. are prent in small amounts but still very important; without them the body can’t function
∙ Most elements aren’t prent in pure form but joined to form compounds
Nutrition-
∙ Nutrients are material that can be taken into cells and are uful to the body
∙ Nutrition is the study of nutrients and their effect on one’s health
∙ Good nutrition is especially important for teenager b/c of the changes taking place in their bodies; a time of rapid growth and development
6.2 Nutrients for Energy
∙ Bodies need ~ 50 different nutrients
∙ 忍耐的意思Most can be classified into one of six groups: carbohydrates, fats, proteins, minerals, vitamins and water
∙ Nutrients in the groups supply body cells with energy needed to function
∙ Energy cells obtain from food is called food energy
∙ B/c energy needed by one’s body is so great food energy is measured in kilojoules有什么无什么
Carbohydrates-
∙ Major source of energy the body needs is from carbohydrates (~ 55%)
∙ Contain carbon, hydrogen and oxygen atoms arranged in certain ways
∙ Simple carbohydrates are made up of small, simple molecules, also called sugars (names end in “o”)
∙ Gluco in the major source of energy for all body cells
∙ Complex carbohydrates are larger molecules and are made of many sugar molecules joined together
∙ A complex carbohydrate often eaten is starch and glycogen
∙ Can’t supply energy to body cells immediately and need to be broken into the small sugar molecules they are made of (this process is digestion)
有教无类的意思
九江区号∙ Some leftover gluco molecules are stored for future u as glycogen molecules (usually in muscles and the liver)
Fats-
∙ Another source of energy comes from fats
∙ Fats come from meats, margarine, eggs, dairy products, nuts and oils
∙ Fat molecules are mad up of carbon, hydrogen and oxygen atoms but fat molecules contain many more hydrogen atoms and fewer oxygen atoms
∙ Eat fat molecule contain smaller molecules called fatty acids
∙ The body stores much of its energy in body fat
∙ Saturated fats contain as many hydrogen atoms as possible and are found in animal products (ie. meat, milk, chee, eggs, butter)
∙ Unsaturated fats have spaces in which more hydrogen atoms can be added and usually come from plant products (ie. corn, peanut oil)
∙ No more than 30% of food energy should be from fats (no more than 10% saturated fats)
∙ High amounts of saturated fats increa the amount of cholesterol, a fat-like compound found in animal products, in the blood
6.3 Proteins: Nutrients for Growth and Repair
∙ Proteins form an important nutrient group
∙ Main function is to help body cells work properly and help in building and repairing the cells
∙ The building blocks of proteins are amino acids (compod of nitrogen, hydrogen, oxygen and carbon atoms)
∙ A molecule of protein is compod of many amino acid molecules joined together
∙ One required 20 amino acids to make all proteins needed
∙ The body can make 12 from atoms supplied by other nutrients eaten, the are the non-esntial amino acids since one doesn’t have to eat foods containing them
联合办厂∙ The body can’t make 8 amino acids, which are the esntial amino acids since one needs to eat foods containing them茶话
∙ Some proteins are called complete proteins becau they contain all eight esntial amino acids in adequate amounts
∙ Some proteins that are missing one or more of the eight esntial amino acids are incomplete proteins
How Your Body Us Proteins-
∙ Proteins are needed in every cell
∙ Some proteins form bones, hair, skin and nails
∙ Sen organs, nerves and the brain wouldn’t work without other proteins
∙ Most important proteins are enzymes, proteins that speed up the rates of chemical reactions within the body
∙ For energy the body first us gluco or fatty acids and if none are available then amino acids are ud
∙ The body can’t store amino acids so if too many proteins are eaten they are converted into fat (change can’t be reverd)
∙ If not enough protein is eaten the body breaks down body parts to obtain amino acids needed
