CHAPTER I
INTRODUCTION
1.1 Abstract
Nutrients are subtances in food that provide energy and materials for cell development growth and repair. There are six kinds of nutrients avaible in foods: carbohydrates, proteins, lipids, vitamins, minerals and water. These nutrients can be classified as organic nuterients and inorganic nutrients. Carbohydrates, proteins, vitamins, and lipids are organic nutrients. In contrast, minerals and water inorganic nutrients.
Carbohydrates, proteins, vitamins, and lipids are organic nutrients. In contrast, minerals and water are inorganic nutrients. Food containing carbohydrates, proteins and lipids are usually too complex to be absobed directly by your body. These subtances need to be broken down into simpler molecules before the body can makeuse of them. In contrast, minerals and water can be absorbed directly into your bloodstream. They do not require digestion or breakdowns.
1.2 Rationale
Do you eat every morning? What kinds of food do you need? Rice, potatoes, corn? Rice, potatoes and corn are example of food containing mostly carbohydrates. Carbohydrates are the main sources of energy for your body. Do you know what energy is? As you already know the energy is the capacity of matter to peform work.
The three form of carbohydrates are cellulose, starch, and sugar. Starch and cellulose are complex carbohydrates. Cellulose occurs in plant cell walls. Starch is in such food as corn, potatoes, and rice. Cellulose and starch are made up of a large number of subunits or building blocks called monosaccharide (simple sugar). There are many types of sugar.Sugar is a simple carbohydrate. Fruits, honey, and milk are sources of sugar. Your cells use sugar in the form of glucose.
Carbohydrates contain carbon, hydrogen, and oxygen atoms. When molecules of carbohydrates bereak down in your cells during respiration, energy is released. The carbohydrate produced by the green plants will be used as the main energy resource for human and animals. Human and animals cannot make on their own the organic materials, therefore, there are called heterotropic organism. Heterotropic organism are depended on the autotropic organisms for their energy and nutrition.
Organisms use carbohydrates to make complex substances. Among the subtances are starches (amilium), proteins, fats, enzymes, vitamins, and hormones. For example, thousands of molecules of glucose make up starch. To make an amino acid those elements react with nitrogen (N) and sulphur (S) in a certain way. Thousand molecules of amino acids make up protein. The same priciple is used to compose fats from carbohydrates. The process of synthesizing a complex subtance is called anabolism.
Organisms use carbohydrates to get their energy. This reaction is called oxidation, which happens inside cell; therefore it is also called cellular respiration. In this process the complex molecules of carbohydrate, such as starch are broken down into the smallest molecules of such subtances as glucose.Glucose then reacts with oxygen to produce energy. The process of breaking down a complex molecule into a simple ones is called catabolism.
Proteins and fats can also be converted into simple molecules to gain energy. Approximately 50% of our energy is from carbohydrates, 35% is from proteins, and 15% is from fats. Therefore, carbohydrates are considered an energy resource.
You need enzymes to break down food in your digestive tract or in the other process in your cells. An enzyme is an example of the protein that you need for catalyzing metabolis reaction. You also need protein as a nutrient for growth, replacement or repairing body cells.
The protein molecule contains carbon, hydrogen, oxygen and nitrogen atoms.Like carbohydrates, a protein molecule is made up of a large number of subunits called amino acids. Your body needs 20 different amino acids to be able to construct the protein that you need in your body. Most of the amino acids can be made in your cells. The eight remaining amino acids are called essential amino acids. Your body doesn’t have the genetic instruction to constract them in your cells. Therefore, they have to be imported through the food in your diet. Eggs, milk, and chesse contain all of the essential amino acids. Beef, fish, chicken and nuts only supply one of them. You might be suprise to know that all grains such as wheat, rice and soy bean supply many needed amino acids in addition to carbohydrates. Eggs, milk, and chesse contain all of the essential amino acids. Beef, fish, chicken and nuts only supply one of them.
The function of fats is to provide energy and help your body to store some vitamins. But for good health your diet should not be more than 30% fat. Fat can be stored in your body in the form of that fat tissue that cushions your internal organs. A molecule of fat release more energy than a molecule of carbohydrate.During the digestion process, a single molecule of fat breaks down into smaller molecules called fatty acid and glycerol. There are two kinds of fats: unsaturated and saturated fats. Plants such as corn and soy bean oil, have unsaturated fats. Some unsaturated fats are also found in poultry, fish, and nuts. Saturated fats are found in red meats. This type of fat has been associated with high level of blood cholestrol that contributes to heart disease.
Vitamins are complex organic compounds needed in small quantities for good health. Lack of a specific vitamin in a diet results in a vitamin deficiency disease. Vitamins do not provide energy or rebuild tissue, but vitamins are used to make enzymes. There are many kinds of vitamins such as vitamin A, B, C, D, E , dan K.
For years man has known that the absence of certain food in the diet results in a disease. Sailors who went for months without fresh fruits or vegetables became ill. They got the disease called scurvy. A person with scurvy has sore, bleeding gums and suffers from lack of energy. The British Navy discovered a way to prevent scurvy among seamen. The sailors carried limes with with them on ocean voyages and were required to eat them. Eating limes or other citrus fruits, such as oranges, grapefruits and lemons prevents scurvy.
Today it is known that scurvy is caused by a lack of vitamin C. Rickets is another deficiency disease. It is caused by a lack of vitamin D, phosphorus, and calcium. If oneof these essential subtances is lacking in the diet of children, rickets, will develop. Absence of vitamin D result in improper bone growth. The bones of a person with rickets may be curved or warped.
All the vitamins needed by man are present in food. Also, many kinds of food have been enriched with added vitamins. For example, vitamin D is added to milk and B vitamins are added to flour. The most economical way to obtain the vitamin you need is to eat a balanced diet. Normally people who eat a balanced diet obtain sufficient vitamins. They do not need vitamin pills. Vitamin pills should be taken only upon the advice of a doctor for treating a special health problem. Vitamins, their functions and food sources.
Have you ever been without drinking water for a long time? How did you feel? A loss of 10 percents of the body’s water results in serious illness. A loss of 20 percent usually results in death.
Water is an inorganic compound containing two atoms of hydrogen and one atom of oxygen in each molecule. About 60-70 percent of your body is water. Water is one of the main substances in cytoplasm. About 90 percent of blood plasm is water.
Water is in vital in many ways. Water is used in digestion to split complex food molecules into simple molecules. Digested food is dissolved in water when it is absorbed by blood. Waste is removed from the blood in the form that dissolve in water such as sweat and urine. The evaporation of water from our skin helps regulate body temperature. Evaporating water reduces body temperature when you are overheated.
You obtain water by driniking or through the food that you eat. All the foods you eat contain water. Vegetables and fruits have a high-water content. Some water is produced when food is broken down within the cells.
Minerals are elements needed by the body. Vegetables, fruits, fish, meat, eggs, milk and cereals are rich in these minerals. Minerals are vital in many ways. Calcium and phosphorus are essential for the formation of strong bones and teeth. Milk and other dairy products are sources of calcium and and phosphorus. Iron is required for the formation of hemoglobin. Iodine is used in the formation of thyroxin, a hormone produced by the thyroid gland. Chlorine is used in the formation of hydrochloric acid by glands in the stomach. Sulfur is present in protein. For example the human hair which is mostly protein, contains 4-6 percent the sulfur.
Minerals used by the body must be in compound forms. This means that mineral must be combined chemically with other elements. For example sodium and chlorine combined together as salt are also required by the body.
The heat energy value of food is measured in calories (C). There is what is known as the “large Calorie”. One large Calorie is the amount of heat needed to raise the temperature of 1000 g of water 1°C. The value of a “large Calorie” is 1000 times the value of the “small calorie”. One small calorie (small c) is the amount of needed energy to increase temperature of one gram of water 1°C.
Calories are measured with calorimeter. A calorimeter consits of a chamber made of steel. The chamber is surrounded by a container holding a known amount of water. The sample of food is placed in the steel chamber. Then the chamber is fiiled with pure oxygen. The food is burned with electric sparks. The heat released from the burning food is absorbed by the water. The increase in the water temperature is used to determine the calorie released from the food. Suppose the heat from the sample of food increases the temperature of 3 kg of water 2°C. Six Calories of heat are produced. Calories = kilograms of water x degree Celcius change in temperature.
Carbohydrates, proteins and fats are good sources of energy. Fats and protein have a higher energy content than carbohydrates. Fats and protein yield 2.25 times as much as energy per gram than carbohydrates. Fats take only about 1 tablespoon to yield 100 calories. The digestion tract is a long tube through which food passes. The organs of your digestive tract include the mouth, esophagus, stomach, small intestines, large intestines, rectum and anus. The food that you eat passes through all these organs. However, food does not pass through the liver, pancreas, gall bladder, and salivary glands. These are all called digestive glands, which produce or store enzymes and chemicals that help break down food as it passes
Home 
Portal 
