Blood is a liquid tissue thatperforms the most important functions. However, in different organisms, its elements differ in structure, which is also reflected in their physiology. In our article we will dwell on the features of red blood cells and compare the red blood cells of a human and a frog.
Variety of blood cells
The blood is formed by a liquid extracellular substancewhich is called plasma, and shaped elements. These include white blood cells, red blood cells and platelets. The former are colorless cells that are not of permanent shape and move independently in the bloodstream. They are able to recognize and digest foreign particles for the body by phagocytosis, and therefore form an immune system. This is the body's ability to resist various diseases. Leukocytes are very diverse, have immunological memory and protect living organisms from the moment of their birth.
Platelets also perform a protective function.They provide blood clotting. The basis of this process is the enzymatic reaction of the transformation of proteins with the formation of their insoluble form. As a result, a blood clot is formed, which is called a thrombus.
Features and functions of red blood cells
Erythrocytes, or red blood cellsare structures containing respiratory enzymes. Their shape and internal content may vary in different animals. However, there are a number and common features. On average, red blood cells live up to 4 months, after which they are destroyed in the spleen and liver. The place of their formation is the red bone marrow. Red blood cells are formed from universal stem cells. Moreover, in newborns, all types of bones have hematopoietic tissue, and in adults, only in flat ones.
In animals, these cells performa number of important functions. The main one is respiratory. Its implementation is possible due to the presence of special pigments in the cytoplasm of erythrocytes. These substances also determine the color of the blood of animals. For example, in mollusks it may be purple, and in polychaete worms it may be green. Red blood cells of a frog provide its pink color, and in humans it is bright red. Connecting to the lungs with oxygen, they carry it to every cell in the body, where they give it away and add carbon dioxide. The latter comes in the opposite direction and exhales.
Erythrocytes also transport amino acids,performing a nutritional function. These cells are carriers of various enzymes that can affect the rate of chemical reactions. Antibodies are located on the surface of erythrocytes. Thanks to these proteinaceous substances, red blood cells bind and neutralize toxins, protecting the body from their harmful effects.
The Evolution of Red Blood Cells
Эритроциты крови лягушки являются ярким примером intermediate result of evolutionary transformations. For the first time, such cells appear in primordial animals, which include ribbon-like nemertine worms, echinoderms and clams. In their most ancient representatives, hemoglobin was located directly in the blood plasma. With the development of animal demand for oxygen increased. As a result, the amount of hemoglobin in the blood increased, making the blood more viscous, and difficult breathing. The way out of this was the emergence of red blood cells. The first red blood cells were rather large structures, most of which are occupied by the nucleus. Naturally, the content of the respiratory pigment in this structure is insignificant, because it simply does not have enough space.
В дальнейшем эволюционные метаморфозы развивались in the direction of reducing the size of red blood cells, increasing the concentration and disappearance of the nucleus in them. At the moment, the biconcave form of red blood cells is the most effective. Scientists have shown that hemoglobin is one of the most ancient pigments. It even occurs in cells of primitive ciliates. In the modern organic world, hemoglobin left behind a dominant position along with the existence of other respiratory pigments, since it carries the greatest amount of oxygen.
Blood Oxygen Capacity
In arterial blood simultaneously boundcondition can be only a certain amount of gases. This indicator is called the oxygen capacity. It depends on a number of factors. First of all, this is the amount of hemoglobin. Red blood cells of the frog in this regard are significantly inferior to the red blood cells of humans. They contain a small amount of respiratory pigment and their concentration is low. For comparison: amphibians' hemoglobin, contained in 100 ml of their blood, binds an oxygen volume of 11 ml, and in humans this figure reaches 25.
The factors that increase the ability of hemoglobin to add oxygen include an increase in body temperature, the pH of the internal environment, the concentration of intracellular organic phosphate.
The structure of the red blood cell frog
Examining a frog's red blood cells under a microscope,it is easy to see that these cells are eukaryotic. All of them have in the center a large decorated core. It occupies a fairly large space compared with respiratory pigments. In this regard, the amount of oxygen that they can carry is significantly reduced.
Comparison of human erythrocytes and frogs
Красные клетки крови человека и земноводных имеют a number of significant differences. They significantly affect the performance of functions. Thus, human erythrocytes do not have a nucleus, which significantly increases the concentration of respiratory pigments and the amount of oxygen carried. Inside them is a special substance - hemoglobin. It consists of protein and iron-containing part - heme. Frog erythrocytes also contain this respiratory pigment, but in much smaller quantities. The efficiency of gas exchange also increases due to the biconcave shape of human erythrocytes. They are rather small in size, therefore their concentration is greater. The main similarity of human erythrocytes and frogs is the implementation of a single function - the respiratory one.
Red blood cell size
The structure of the red blood cell frog is characterized by rather large sizes, which reach a diameter of up to 23 microns. In humans, this figure is much less. Its red blood cells have a size of 7-8 microns.
Concentration
Due to the large size of red blood cellsfrogs are characterized by low concentrations. So, in 1 cubic mm of amphibian blood there are 0.38 million. For comparison, this number in humans reaches 5 million, which increases the respiratory capacity of his blood.
Red blood cell form
Examining a frog's red blood cells under a microscope,You can clearly define their rounded shape. It is less beneficial than biconcave discs of red human blood cells, since it does not contribute to an increase in the respiratory surface and occupies a large volume in the bloodstream. The correct oval shape of the red blood cell of the frog completely repeats that of the nucleus. It contains chromatin threads containing genetic information.
Cold blooded animals
Форма эритроцита лягушки, как и его внутреннее structure, allows you to carry only a limited amount of oxygen. This is due to the fact that amphibians do not need as much of this gas as mammals. It is very easy to explain. In amphibians, breathing is carried out not only through the lungs, but also through the skin.
Данная группа животных является холоднокровными.This means that their body temperature depends on the change of this indicator in the environment. This feature directly depends on the structure of their circulatory system. So, between the chambers of the heart of amphibians there is no partition. Therefore, in their right atrium, venous and arterial blood mixes and in this form goes to the tissues and organs. Along with the structural features of red blood cells, this makes their gas exchange system not as perfect as that of warm-blooded animals.
Warm-blooded animals
In warm-blooded organisms, body temperatureconstant. These include birds and mammals, including humans. Their body does not mix venous and arterial blood. This is a result of having a full septum between the chambers of their heart. As a result, all arteries and organs except lungs receive pure arterial blood saturated with oxygen. Along with more perfect thermoregulation, this contributes to an increase in the intensity of gas exchange.
So, in our article we looked at whatfeatures have human erythrocytes and frogs. Their main differences relate to the size, the presence of the nucleus and the level of concentration in the blood. Red frog cells are eukaryotic cells, have larger sizes, and their concentration is low. Because of this structure, they contain a smaller amount of respiratory pigment, so the pulmonary gas exchange in amphibians is less effective. This is compensated by the additional system of skin respiration. Features of the structure of erythrocytes, circulatory system and mechanisms of thermoregulation determines the cold-bloodedness of amphibious animals.
The structural features of these cells in humans are moreprogressive. The biconcave shape, small size and absence of the core significantly increase the amount of oxygen transferred and the intensity of gas exchange. Human erythrocytes more effectively perform the respiratory function, quickly saturating all the cells of the body with oxygen and releasing from carbon dioxide.
