Blood is a liquid tissue that performs essential functions. However, in different organisms, its elements differ in structure, which is reflected in their physiology. In our article, we will dwell on the features of red blood cells and compare human and frog red blood cells.
Blood cell diversity
Blood is formed by a liquid intercellular substance called plasma, and by shaped elements. These include white blood cells, red blood cells, and platelets. The first are colorless cells that do not have a constant shape and independently move in the bloodstream. They are able to recognize and digest particles alien to the body through phagocytosis, therefore they form immunity. This is the body's ability to withstand various diseases. White blood cells are very diverse, have an immunological memory and protect living organisms from the moment they are born.
Platelets also have a protective function. They provide blood coagulation. The basis of this process is the enzymatic reaction of the conversion of proteins with the formation of their insoluble form. As a result, a blood clot forms, which is called a blood clot.
Features and functions of red blood cells
Red blood cells, or red blood cells, are structures containing respiratory enzymes. Their shape and internal contents in different animals may vary. However, there are a number of 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 form 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 perform a 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 can be lilac, and in polychaete worms it can be green. The red blood cells of the frog provide its pink color, and in humans it is bright red. Combining in the lungs with oxygen, they carry it to every cell in the body, where they give it away and attach carbon dioxide. The latter enters in the opposite direction and exhales.
Red blood cells 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 red blood cells. Thanks to these substances of a protein nature, red blood cells bind and neutralize toxins, protecting the body from their pathogenic effects.
The Evolution of Red Blood Cells
Frog blood red blood cells are a prime example of an intermediate result of evolutionary transformations. For the first time, such cells appear in primary animals, which include ribbon-shaped worms, nemerthins, echinoderms, and mollusks. In their most ancient representatives, hemoglobin was located directly in the blood plasma. With the development of animals, the need for oxygen increased. As a result, the amount of hemoglobin in the blood increased, which made the blood more viscous and made breathing more difficult. The way out of this was the appearance of red blood cells. The first red blood cells were quite large structures, most of which are occupied by the nucleus. Naturally, the content of respiratory pigment with such a structure is insignificant, because it simply does not have enough space.
Subsequently, evolutionary metamorphoses developed towards a decrease in the size of red blood cells, an increase in 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 proven that hemoglobin is one of the oldest pigments. It even occurs in the cells of primitive ciliates. In the modern organic world, hemoglobin has retained 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 at the same time in a bound state can only be a certain amount of gas. This indicator is called oxygen capacity. It depends on a number of factors. First of all, this is the amount of hemoglobin. Frog erythrocytes in this regard are significantly inferior to red human blood cells. They contain a small amount of respiratory pigment and their concentration is low. For comparison: amphibian hemoglobin contained in 100 ml of their blood binds an oxygen volume of 11 ml, and in humans this figure reaches 25.
Factors that increase the ability of hemoglobin to attach oxygen include an increase in body temperature, pH of the internal environment, and the concentration of intracellular organic phosphate.
The structure of red blood cells of a frog
Examining a frog erythrocyte under a microscope, it is easy to notice that these cells are eukaryotic. All of them have a large decorated core in the center. It occupies a fairly large space compared to respiratory pigments. In this regard, the amount of oxygen that they are able to carry is significantly reduced.
Comparison of human and frog red blood cells
The red blood cells of humans and amphibians have a number of significant differences. They significantly affect the performance of functions. So, human red blood cells do not have a nucleus, which significantly increases the concentration of respiratory pigments and the amount of oxygen transferred. Inside them is a special substance - hemoglobin. It consists of protein and an iron-containing part - heme. Frog red blood cells also contain this respiratory pigment, but in much smaller quantities. The efficiency of gas exchange also increases due to the biconcave form of human red blood cells. They are quite small in size, and therefore their concentration is greater. The main similarity of human and frog red blood cells lies in the implementation of a single function - respiratory.
Red blood cell size
The structure of the frog erythrocytes 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, red blood cells of the frog are characterized by a low concentration. So, in 1 cubic mm of amphibian blood there is 0.38 million of them. For comparison, in humans this amount reaches 5 million, which increases the respiratory capacity of his blood.
Red blood cell
Examining the frog erythrocytes under a microscope, one can clearly determine their round shape. It is less beneficial than the biconcave disks of red blood cells of a person, because 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 frog erythrocyte completely repeats that of the nucleus. It contains chromatin strands containing genetic information.
Cold-blooded animals
The frog erythrocyte shape, like its internal structure, allows only a limited amount of oxygen to be transferred. 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.
This group of animals is cold-blooded. This means that their body temperature depends on the change in this indicator in the environment. This symptom 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 way enters the tissues and organs. Along with the structural features of red blood cells, this makes their gas exchange system not as perfect as in warm-blooded animals.
Warm-blooded animals
In warm-blooded organisms, body temperature is constant. These include birds and mammals, including humans. In their body, there is no mixing of venous and arterial blood. This is the result of having a complete septum between the chambers of their heart. As a result, pure arterial blood saturated with oxygen enters all tissues and organs except the lungs. Along with better thermoregulation, this contributes to an increase in gas exchange intensity.
So, in our article, we examined what features have human and frog red blood cells. Their main differences relate to the size, presence of a nucleus and the level of concentration in the blood. Frog erythrocytes are eukaryotic cells, are larger, and their concentration is low. Due to this structure, they contain less respiratory pigment, so pulmonary gas exchange in amphibians is less effective. This is offset by an additional system of skin respiration. Features of the structure of red blood cells, the circulatory system and thermoregulation mechanisms are determined by the cold-blooded nature of amphibians.
The structural features of these cells in humans are more progressive. The biconcave shape, small size and lack of a core significantly increase the amount of oxygen transported and the gas exchange rate. Human red blood cells more effectively carry out respiratory function, quickly saturating all cells of the body with oxygen and freeing from carbon dioxide.