Chapter 4. Cell doctrine (fundamentals of general cytology)
The basis of the structure of eukaryotic organisms is the smallest unit of living things — a cell (cellula).
A cell is an ordered structure bounded by an active membrane and consisting of biopolymers (nucleic acids, proteins, polysaccharides, lipids) and their macromolecular complexes that form the nucleus and cytoplasm, providing the maintenance and reproduction of the system as a whole.
Apart from cells, the body contains their derivatives: symplast, syncytium, intercellular substance (see Chapter 6).
The cell is an elementary structural, functional and genetic unit in the composition of plants, animals and humans. Being elementary in relation to a multicellular organism, at the same time it has a complex structure, functional organization and high degree of organic integrity and individuality. The cell is capable of self-reproduction and can potentially give rise to a whole new multicellular organism.
The general features of the structure and functioning of cells are studied by cytology, or cell biology, as it is currently named. It explores individual cellular structures, their participation in general cellular physiological processes, ways of regulating these processes, reproduction of cells and their organelles, adaptation of cells to environmental conditions, reactions to the effects of various factors. Studying cytology is of great importance for medicine, since almost all human diseases are the result of various cellular lesions or dysfunction of cells in the tissues of various organs.