Nutrients: Classification of nutrients, Substances that provide energy, Nutrients and plants
Nutrient
A nutrient or nutrient is a chemical from outside the cell and that it needs to perform its vital functions. This is taken by the cell and converted into a cellular component through a process called anabolism biosynthetic metabolic or is degraded to obtain energy and other molecules.
The nutrient is any element or compound necessary for the metabolism of a living being. That is, the nutrients are some of the substances contained in foods that are actively involved in metabolic reactions to maintain body functions.
From the standpoint of botany and ecology, basic nutrients are oxygen, water and minerals necessary for plant life, which through photosynthesis incorporate living matter, thus forming the basis of the chain Food, once these plants will be fed to animals.
Living things are not photosynthetic capacity, such as animals, fungi and many protoctists, feed on plants and other animals, either living or decaying. For these beings, nutrients are organic and inorganic compounds in foods and, according to their chemical nature, are classified into the following types of substances:
- Protein.
- Carbohydrates.
- Lipids.
- Vitamins.
- Mineral salts.
- Water
Special mention must be made with the fiber, since it is not strictly a nutrient. Certainly part of some foods (vegetables), develops physiological functions of interest (contributes to bowel motility may regulate plasma lipoprotein levels or modifies the postprandial blood glucose), but their constituents are not actively involved in metabolic processes necessary for the body .
Classification of nutrients
Depending on the importance
In terms of participation in metabolic reactions of the organism as a whole, the nutrients can be:
- Nutrients Nonessential which are not vital to the body and that, under certain conditions, are synthesized via precursor molecules (usually essential nutrients). Therefore, the body does not need regular intake of such a condition to obtain the precursors of their environment. These are produced by the body's metabolism.
- Essential nutrients: those that are vital to the agency as you can not synthesize. That is, are substances that are so indispensable to obtain the environment. For humans, these include essential fatty acids, essential amino acids, some vitamins and certain minerals. Oxygen and water are also essential for human survival, but usually not considered as nutrients when consumed in isolation.
Humans can get energy from a variety of fats, carbohydrates, proteins and ethanol and other compounds can be synthesized (eg, certain amino acids) from essential nutrients.
The nutrients have a significant role on health, whether beneficial or toxic. For example, sodium is a nutrient that is involved in water balance processes when provided in adequate amounts. But his excessive intake in the diet can promote hypertension.
According to its mass
Depending on the quantity necessary for cells and organisms are classified as:
- Macronutrients are required in large quantities daily (usually in the order of grams). These nutrients are involved as substrates in metabolic processes for energy. Include proteins, carbohydrates and fats. They are the basis of any diet.
- Micronutrients are needed in small quantities (usually in amounts less than milligrams). These nutrients are involved in regulating metabolism and energy processes, but not as substrates. Are vitamins and minerals.
According to its function
Although a single nutrient can perform several functions can be classified into:
- Energy: those that serve as metabolic substrate for energy, so that the body can perform the necessary functions. For example, fats, carbohydrates and proteins.
- Plastic or structural: those that form the structure of the organism. Also allow for growth. For example, proteins, carbohydrates, certain lipids (cholesterol) and some mineral elements (calcium, phosphorus, etc.)..
- Regulators: the chemical reactions that control the regulators metabolismo.Son nutrients vitamins and some minerals (sodium, potassium ...).
Substances that provide energy
- Carbohydrates are compounds composed of monosaccharides. Carbohydrates are classified by the number of sugar units: monosaccharides (such as glucose and fructose), disaccharides (such as sucrose and lactose), oligosaccharides and polysaccharides (such as starch, glycogen and cellulose).
- Proteins are organic compounds consisting of amino acids joined by peptide bonds. The body can not manufacture some amino acids (called essential amino acids). The diet must supply these amino acids. In nutrition, proteins are degraded by protease to free amino acids during digestion.
- Fat is a molecule of glycerol with three fatty acids attached. Fatty acids are long unbranched linear hydrocarbon chain, connected by single bonds alone (saturated fatty acids) or double and single bonds (unsaturated fatty acids).
Fats are necessary to maintain the proper functioning of cell membranes to isolate the viscera against shock, maintaining body temperature stable and to maintain healthy hair and skin. The body does not manufacture certain fatty acids (called essential fatty acids) and the diet should supply them.
Fat has an energy content of 9 kcal / g (37.7 kJ / g), protein and carbohydrates have 4 kcal / g (16.7 kJ / g). Ethanol has the energy content of 7 kcal / g (29.3 kJ / g).
Nutrients and plants
The chemical elements consumed in greater quantities by plants are carbon, hydrogen and oxygen. This is present in the environment in the form of water and carbon dioxide, energy is provided by sunlight. Nitrogen, phosphorus, potassium and sulfur are also needed in relatively large quantities. Together, these are the elemental macronutrients for plants.
Usually these are obtained from inorganic sources (eg carbon dioxide, water, nitrate, phosphate and sulfate) or organic compounds (eg carbohydrates, lipids and proteins), although the diatomic molecules of nitrogen and oxygen are often used. Other chemicals are also required to carry out various processes and build structures.
An oversupply of nutrients to plants in the environment can cause excessive plant growth and algae. This process is called eutrophication may cause a balance in population numbers and other nutrients that may be harmful to certain species. For example, an algae bloom can deplete the oxygen available for fish respiration. Causes include water pollution from sewage from farms (containing an excess of fertilizer). Nitrogen and phosphorus are usually the limiting factor in growth and therefore most likely to trigger eutrophication when introduced artificially.
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