..................................................
|
Activities to do. Read the explanations on nutrition and types of nutrients and perform the first Multiple Choice Test. Then read the explanations on nutrient requirements and perform the second Multiple Choice Test and the Crossword.
1. The nutrients. Are the substances that give us the energy we
need to keep us alive and the matery that we need to grow and develop.
The nutrients are the chemical substances that constitute food
and also those that are the subject of our body. Examples of nutrients
include glucose, amino acids, fatty acids, etc.
2. The food. Are the products from which we get the nutrients necessary for life. The food is everything we eat or drink that results in nutrients. Examples of foods are fruits, meat, milk, eggs, etc.
3 . The nutrition. Strictly speaking it is the set of chemical reactions through which the body gets, processes and uses nutrients from food. For example the energy in the cell is obtained from the glucose. This set of reactions is a process that occurs automatically, directly and independently of our will. Generally speaking, the function of nutrition also includes all of the processes that accompany the previously mentioned, ie feeding, digestion, respiration, circulation and excretion.
4 . The feeding. It is the action of taking and ingesting food, ie eating and drinking. The feeding is a discontinuous and voluntary process therefore it can be trainable.
5
. Types of the nutrients. We distinguish the
following types:
During the process of digestion, starch is decomposed into hundreds of glucoses through the action of digestive enzymes "amylases"
Carbohydrates.
Its function is to provide energy (around 4kcal/g). We distinguish
simple carbohydrates or sugars such as glucose,
sucrose
and fructose
in fruits and lactose
in milk; and complex carbohydrates or starches such as starch
in the cereals, leguminous plants and potatoes. Some carbohydrates does
not provide the energy because we cannot digest them. It happens in the
case of cellulose, constituently called the "plant fiber". It
serves us to regulate the intestinal transit by increasing the volume
of stool.
In the course of the digestion of fats or triglycerides
they are being broken down into glycerol and fatty acids
through the action of digestive enzymes "lipases"
Lipids. Its main function is to provide energy (around 9kcal/g). Other functions are to constituite structures (eg the plasma membrane, the protecting kidneys fats, etc..), to constitute energy reserves (eg adipose tissue), the thermal insulation (eg adipose panicle) and to favor reactions (eg lipid vitamins). The most known lipids are triglycerides and fatty acids from animal fats and from vegetable oils and cholesterol, which is very abundant in the egg yolks.
In the course of the digestion of the proteins they are being decomposed into tens of amino acids through the action of digestive enzymes "proteases"
Proteins. They perform many functions. The main two are constituting structures (such as actin and myosin proteins from the muscle and collagen protein from the bones, cartilages, tendons and ligaments), and constituting the enzymes which are the molecules that regulate the digestion of food and all chemical internal reactions within the cells. Other functions include constituting antibodies and some hormones such as growth hormone and the insulin hormone, and serving as an energy source in case of extreme necessity (4kcal/g) such as the blood albumin.
Water. Its main function is to constitute the environment in which all of the chemical reactions of living beings are being performed. Besides of constituting the internal environment of the cells, it also constitute the intercellular fluid and the internal medium of circulation of the animals, such as blood and lymph, and the internal medium of the plants, known sap. Therefore it means that it is the medium that carries the nutrients. It is found in all foods in bigger or smaller proportion.
Mineral substances. They are inorganic substances that perform different roles such as constituting skeletal structures (as calcium phosphate and calcium carbonate of the bones), maintain internal environmental salinity (as sodium chloride and potassium chloride in the blood) and intervene in the establishment of specific chemicals (such as iron in the hemoglobin and iodine of the hormone thyroxine). See the attached image of sodium chloride (NaCl) dissolved in water.
6. The nutrient requirements.
According to the quantity of need of each type of nutrient we distinguish
macronutrients, which are those that are needed in large quantities,
since they serve to supply energy and to build structures of the body,
and micronutrients, which are needed in very small quantities,
but without them it is impossible to live, as they are the ones regulating
specific chemical reactions. Examples of macronutrients are sugars,
starches, triglyceride or fats, proteins
and water. Examples of micronutrients are vitamins
and some minerals such as iodine,
iron,
lithium,
etc.
7. The energy from food.
Inside the cells the nutrients can combine with oxygen and release the
carbon dioxide, water and energy. This energy is usually expressed in
calories or kilocalories. One calorie is the exact
amount of heat required to raise the temperature in one gram of water
of one centigrade. A kilocalorie is 1000 calories. If you ingests
too much food the remaining energy is stored mainly in the form of lipids,
since it is the type of molecules that holds more energy in less weight.
The energy requirements vary according to the age. Between 15 and
18 years the maximum is given which is 2500 kcal/day for women and 3000
kcal/day for men. It also varies according to the activities. For
example sitting requires 100 kcal/hour, walking 160 kcal/hour and walking
fast 320 kcal/hour). This demonstrates the need for exercise when food
is superabundant, as happens in developed countries.
8 . Healthy and balanced diets. Diet
means a the set of all types of food we normally eat, as well as their
quantity and proportion. Is it considered good diet when it is complete
and balanced.
1. Complete means
that it contains all the nutrients we need (carbohydrates, lipids,
proteins, water and minerals).
2. Balanced means that the proportion between the nutrients
is adequate.
Nutritional requirements vary from one person to another and are difficult to evaluate. If on a normal diet the health of a person is good and its weight is right, we can deduce that their nutritional needs are adjusted average.
9 . The prevention of diseases caused by malnutrition. To avoid diseases related to poor nutrition is appropriate to follow these guidelines:
1. To eat all the types of food without quitting any. This means that we have to eat at least a little of the ones we like less and avoid eating too much of those we like the most.
2. To eat the right amount in order not to gain weight or get thinner. It is convenient to weigh yourself with some regularity. It should be noted that in periods of growth there always is an increase in weight.
3. Not to overuse sweets or fats. Instead it is necessary to eat vegetable fiber every day (found in fruits and vegetables) to facilitate bowel movement and defecation.
4. To alternate meat with fish as protein sources. Too much animal protein can cause diseases such as gout (joint pain during the excess of urate).
5. Do not abuse the eggs or animal fats for its high content of cholesterol, which can be deposited inside arteries and cause heart attacks.
6. To eat fruits and salads. Since they are usually eaten raw, they are very rich in vitamins. These substances are also present in the vegetables, meats and fish, but as they are very sensitive to heat, they are destroyed by cooking them.
7. To distribute the meals throughout the day, ensuring that the breakfast is abundant and the dinner is limited if shortly after going to sleep, and keep to regular hours of meals.
8. To drink 1.5 to 2 liters of water every day.
9. Not to abuse of the salt (less than 3g a day) to prevent kidney and blood pressure problems.
10. To avoid alcoholic spirits (gin, brandy, etc..) As they are very toxic to the liver.
11. In case of the diarrhea, to drink plenty of fluids (in order to prevent dehydration), eat rice and boiled carrot, boiled fish and boiled apple or yogurt. Avoid raw foods and the ones that are rich in fiber.
12. In case of the constipation is recommended to ingest a lot of vegetables, prunes and wheat bread and drink lots of water so that the vegetable fiber can be absorbed and increase the volume.
Biology
topics Index