Normal life of an organism is possible only under the condition of continuous intake of nutrients and removal of end products of transformation. From our article you will learn how metabolic processes occur in individuals of different species.
What is metabolism
Even from a textbook on biology, everyone remembers that the metabolic process consists of two interrelated parts. This is dissimilation and assimilation. In the first case, the splitting 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 is released. When splitting the same amount of fat, energy is released 2 times more.
The essence of assimilation lies in the formation of organic substances characteristic of the body. Thus, metabolism is the process of substances entering the body, their transformation with the formation of energy and the removal of decay products from it.
What substances are necessary for lifeorganism
Normal life of any individual is possible under the condition of a constant supply of food. In addition to organic substances, the body also needs minerals. First of all, it is water, which is a solvent for most chemical compounds and the basis for metabolic processes.
Mineral compounds are no less important. The elements that make up their composition regulate many processes. For example, calcium is necessary for blood clotting, iron - for transporting oxygen. 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.
Waste products: biology
In any living organism, as a result of metabolism, organic substances are formed, which are called excrement. Most of them are removed to the external 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 of the substances that organisms secrete are used by other species. For example, oxygen is the by-product of plant cell activity. This gas is the basis for the existence of all life on the planet. Some animals are coprophages. This means that they feed on excrement. Examples are dung beetles, dipteran larvae, rabbits, hares and chinchillas.
Everyone knows the useful waste products of bees: honey, wax, propolis, perga, royal jelly. These substances have antimicrobial,immunostimulating and anti-allergic properties.
Exchange output system
The structure of the excretory system of the body depends on the level of its organization, the way of nutrition and the characteristics of the habitat. In unicellular, sponges and coelenterates, metabolic products are removed through the membrane by diffusion. But there are special structures for this. In protozoa, undigested food residues are excreted anywhere in the cell or through special formations in its membrane. For example, ciliates have powder. Excess water and s alts are removed through contractile vacuoles. Their action also regulates the level of intracellular pressure.
In invertebrates, excretory organs are specialized tubules or tubules that open outward through pores. These may be nephridia, malpighian vessels, or green glands.
From the human body, waste products are excreted 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 can ensure the efficiency of metabolic processes. In this case, the violation of one organ entails a change in the mechanism of action of another. For example, when you sweat more, you produce less urine.
Water
Not all waste products are removed from the body. Some of them are necessary for the normal functioning of cells. But from the excess of such substances, the body mustget rid of.
Let's start with water. 20% of this liquid evaporates through the skin along 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 liquid is excreted through the kidneys with urine - up to 1.5 liters per day. This is half of the total amount of water. There are two stages in the formation of urine: filtration and reabsorption. In a day, a person passes 1500 liters of blood through the kidneys. As a result of filtration, 150 liters of primary urine are formed from it. It is 99% water. By reabsorption, secondary urine is formed - 1.5 liters per day. This process takes place 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 s alts, vitamins. The amount of water in the secondary urine is reduced to 96%.
The skin performs a number of important functions: excretory, metabolic, thermoregulatory. Through the sweat glands, not only water is excreted, but also excess s alts and urea. At the same time, heat is released into the environment. This is especially intense during exercise 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 - erythrocytes. 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 bloodnecessary condition of life.
When entering the cells, oxygen immediately enters into the oxidation reactions 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, carbhemoglobin, is formed. Further, the blood flows into the right atrium, then into the right ventricle and lungs. Here, carbhemoglobin breaks down, releasing carbon dioxide, and is exhaled from the body.
Urea
One more waste product is excreted through the kidneys. It is diamide carbonic acid, 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. It is then transported by the blood stream to the kidneys, from where it is excreted. Violation of this process can lead to the deposition of s alts in the joints and kidneys.
Heavy metal s alts
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 varied. These are inhaled air, tobacco smoke, systematic work with paints and varnishes, water, medicines. Normally, heavy metals do not disrupt metabolism. The danger lies inthat they can accumulate in tissues, causing damage to 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 coordinated work determines the balance of metabolic processes.
