– MINERALS –
Minerals are substances which are crystalline solids and which occur naturally. There are more than twenty different minerals in the body. Three of the most important minerals are calcium, phosphorus, and iron. Calcium and phosphorus work together.
The bony skeletons of vertebrate animals, including man, are composed of calcium phosphate. If people have enough calcium and phosphorus, their bones and teeth will be strong and hard. In addition, their muscles, nerves, and heart will work properly.
Calcium makes up about 2% of the human body. About 99% of that amount is contained in the teeth and bones. Milk and hard cheeses are the best sources of calcium. After the age of 19, people need only 400 to 500 milligrams of calcium a day.
Phosphorus, on the other hand, makes up 1.1% of the human body. A number of high-energy compounds found in our bodies, such as adenosine triphosphate (ATP), contain phosphorus. ATP is capable of transferring as well as storing energy in living cells and is responsible for energy necessary for physical activity.
Iron is a mineral which makes the blood look red and which carries oxygen for our normal physical activities. All lean meats – especially liver whole grains, nuts, some vegetables, and dried fruits are good sources of this mineral. Iron deficiency results in a disease called anemia. Anemic people do not have enough iron in their blood, and this causes their hearts to beat faster so that their bodies can get more oxygen. Such people, therefore, get tired easily, and their skins sometimes look rather white.
1. What two criteria does a subtance have to fulfill in order to be called a ‘mineral’? a) b)
2. What are the minerals absolutely essential for our bodies?
3. What does deficiency in calcium and phosphorus cause in a person’s body? a)
4. Where does the body store most of the calcium?
5. What type(s) of minerals do people need if they want to have sufficient energy to play tennis, for instance?
6. How much calcium does a a) fifteen-year-old person need? b) thirty-year-old person need?
B. Complete the following according to the information in the passage.
1. Iron is essential in blood because
2. are food items rich in calcium.
3. Anemia is caused
4. An anemic person may show certain symptoms or signs. Two of these are: