The normal vital activity of an organism is possible only under the condition of continuous supply of nutrients into it and removal of the final products of transformation. From our article you will learn how metabolic processes occur in individuals of different species.
What is metabolism
From a biology textbook, everyone remembers that the metabolic process consists of two interconnected parts. This is dissimilation and assimilation. In the first case, the decomposition of complex organic substances occurs. They are the source of energy in the body. So, during the oxidation of 1 gram of protein and carbohydrate, 17.2 kJ are released. When splitting the same amount of fat, energy is released 2 times more.
The essence of assimilation is the formation of organic substances characteristic of the body. Thus, metabolism is the process of the entry into the body of substances, their conversion with the formation of energy and the removal of decay products from it.
What substances are necessary for the life of the body
The normal vital activity of any individual is possible subject to constant food intake. In addition to organic substances, the body also needs minerals. First of all, it is water, which is the solvent of most chemical compounds and the basis for metabolic processes.
Mineral compounds are no less important. Elements included in their composition regulate many processes. For example, calcium is needed for blood coagulation, iron - for oxygen transportation. The presence of iodine is a necessary condition for the synthesis of thyroid hormones, and sodium and potassium for the functioning of nerve and muscle cells.
Vital Products: Biology
In any living organism, as a result of metabolism, organic substances are formed, which are called excrement. Most of them are removed into the environment with the help of specialized organs. This process is aimed at maintaining the constancy of the internal environment. In biology textbooks, this process is called homeostasis.
Some substances that organisms secrete are used by other species. So, the product of the vital activity of a plant cell is oxygen. This gas is the basis of the existence of all life on the planet. Some animals are coprophagous. This means that they feed on feces. Their examples are beetles - dung beetles, dipteran insect larvae, rabbits, hares and chinchillas.
Everyone knows the useful vital products of bees: honey, wax, propolis, bee bread, royal jelly. These substances have antimicrobial, immunostimulating and anti-allergenic properties.
Exchange Products Removal System
The structure of the excretory system of the body depends on the level of its organization, the method of nutrition and the characteristics of the environment. In unicellular, sponges, and intestinal, metabolic products are removed through the membrane by diffusion. But there are special structures for this. In protozoa, undigested food debris is excreted anywhere in the cell or through special formations in its membrane. For example, ciliates have a powder. Excess water and salts are removed through contractile vacuoles. Their action also regulates the level of intracellular pressure.
In invertebrates, the excretory organs are specialized tubules or tubules that open outward in pores. It can be nephridia, malpighian vessels or green glands.
Vital products are excreted from the human body by the organs of the digestive, respiratory, urinary systems, as well as through the skin. Each of them has its own specialization, but only their joint work is able to ensure the effectiveness of metabolic processes. Moreover, a violation of one organ entails a change in the mechanism of action of another. For example, with increased sweating, less urine is formed.
Water
Not all waste products are removed from the body. Some of them are necessary for the normal functioning of cells. But the body must get rid of excess of such substances.
Let's start with the water. 20% of this fluid evaporates through the skin with sweat, 15% is exhaled through the lungs. Water is also found in feces and is removed from the body through the intestines.
Most of the fluid is excreted through the kidneys with urine - up to 1.5 liters per day. This is half of the total amount of water. In the process of urine formation, two stages are distinguished: filtration and reabsorption. For a day in a person through the kidneys passes 1,500 liters of blood. As a result of filtration, 150 liters of primary urine are formed from it. It is 99% water. Secondary urine is formed by reabsorption - 1.5 liters per day. This process occurs in the tubules of the nephron. Here, from the primary urine, all the necessary substances are absorbed back into the blood - glucose, amino acids, mineral salts, vitamins. The amount of water in the secondary urine is reduced to 96%.
The skin performs a number of important functions: excretory, metabolic, thermoregulatory. Not only water, but also excess salts and urea is eliminated through the sweat glands. In this case, heat is released into the environment. This is especially intense during physical exertion or high air temperature.
Carbon dioxide
90% of carbon dioxide is removed through the lungs. At the cellular level, gas exchange is carried out by red blood cells - red blood cells. They carry oxygen from the lungs to the cells, and carbon dioxide in the opposite direction. With these substances, erythrocyte hemoglobin forms unstable compounds. Therefore, the movement of blood is a necessary condition for life.
Entering the cells, oxygen immediately enters the oxidation reaction of organic substances. As a result, carbon dioxide is formed. Due to diffusion, it enters the tissue fluid, and then into the capillaries. Here its unstable compound is formed - carbhemoglobin. Further, the blood enters the right atrium, then into the right ventricle and lungs. Here carbhemoglobin breaks down, releasing carbon dioxide, and is exhaled from the body.
Urea
Another kidney product is excreted through the kidneys. This is carbonic acid diamide, or urea. A small amount is removed with sweat. This substance is mainly formed as a result of the oxidation of amino acids. In the body, urea is synthesized from ammonia. For the body, it is a toxin.
Urea is originally formed in the liver. Then, it is transferred to the kidneys by the flow of blood, from where it is excreted. Violation of this process can lead to the deposition of salts in the joints and kidneys.
Heavy metal salts
Substances that belong to this group of waste products are excreted through the liver and intestines. Examples of heavy metals are arsenic, chromium, mercury, cadmium, copper, lead, aluminum, nickel.
The sources of their entry into the body are diverse. These are inhaled air, tobacco smoke, systematic work with paints and varnishes, water, medicines. Normally, heavy metals do not upset metabolism. The danger lies in the fact that they can accumulate in the tissues, causing a violation of all organ systems.
So, a necessary condition for the functioning of the body is to maintain the constancy of its internal environment. Therefore, the activity of physiological systems is constantly regulated by the nervous system and humoral factors. Their well-coordinated work determines the balance of metabolic processes.