Blood is a fluid that circulates in the internal environment of organisms. Comparing it in humans and animals, you can see some difference. Consider, for example, the difference between frog and human blood.
Blood is necessary to maintain life, and on the contrary, the body dies from its significant loss. The main function of this substance, in whatever body it is, is transport. The blood distributes oxygen from the outside in the body. She also carries the nutrients that we get with food. Blood also performs the opposite function - it picks up metabolic products and promotes their excretion.
Microscopic examination of such an important liquid gives an idea of its composition. So, in blood, two parts can be conventionally distinguished: fluid plasma and a set of elements suspended in it. Among the latter, erythrocytes are present. Mainly thanks to these special cells, gas exchange occurs. Each of them contains hemoglobin, which actively attracts oxygen to itself, and on the way back - excreted substances.
It is in erythrocytes that the difference between the blood of a frog and a person is most noticeable. This is how these particles look in an animal:
And here are human red blood cells:
Let's compare the named blood cells according to several criteria:
- Form. Cells of this kind in the frog are oval. In humans, they have a compact round shape.
- The core. It is found only in particles of animal blood. The absence of this component in human erythrocytes helps to free up additional space for hemoglobin, which carries oxygen.
- Size. In reality, in an animal, these bodies are relatively large. In humans, erythrocytes are small in size. In a certain space, small particles are located in greater numbers and denser, thereby increasing the respiratory capacity of the blood.
- Surface. The outlines of the frog's erythrocytes are simple. Meanwhile, in humans, these cells have concavities. Thanks to this feature, the gas is absorbed as efficiently as possible.
Having found out what is the difference between the blood of a frog and a person, we draw a conclusion. So, our blood copes with the absorption and transport of oxygen much better. And this, along with other advantages (a four-chambered heart, separation of the contents of arteries and veins, etc.), explains the warm-bloodedness of mammals, to which humans belong from the standpoint of biology..