What is the selection, and what is its significance in the life of organisms

All living organisms, inhabitants of the Earth, are open biological systems. To maintain their life requires the flow of food, oxygen and water from the environment and the removal of metabolic products. It is clear that such a separation of slags is mandatory for maintaining the homeostasis of a living organism. What is the result of the absence of this principle? Death follows due to the poisoning of cells with their own metabolites.

Evolution has contributed to the emergence of organs that perform the function of removing toxins. Today they are in all representatives of wildlife, from the simplest to the human. In this article we will find out what is the selection, and also study its features, characteristic for the main groups of organisms.

general information

Organisms, consisting of only one cell, have a perfect system of self-regulation and excretion of slags formed as a result of dissimilation. For example, amoeba vulgaris and euglena green remove toxins and excess water through the cell membrane and contractile vacuole. Let us clarify that such a selection of metabolites of protozoa is an adaptation to the structure of the body and the aquatic habitat. Multicellular organisms complicate the process of slag removal. In the flat, round, annelike worms and molluscs appear tubules - proto-or metanefridii.

Crayfish are characterized by green glands, and insects develop malpighian vessels and fatty body. The appearance of the chord and internal skeleton dramatically changes the process of isolation. The biology of vertebrate animals reveals the formation of complex organs - twin kidneys. Let's consider their structure and functions further.

Evolution of excretory system

Fish have ribbon-like trunk kidneys lying on either side of the spine and filtering blood. In amphibians, compact excretory organs are located in the region of the sacral vertebra. Of these, the ureteral urine passes into the cloaca. The appearance of pelvic kidneys in reptiles, birds, mammals and humans is an important aromorphosis.

Renal nephrons carry out two complex physicochemical processes: blood filtration and reabsorption of primary urine. As a result, the blood is completely cleared of toxins, which provides a physiologically normal level of homeostasis.

Finally

In this article, we examined what a selection is. Now you know the features of this process in different groups of living organisms.