Biology: tissue is a group of cells that are similar in structure and function

According to biology, tissue is a special structure that ensures the functioning of any organism as a whole. What features of the structure need to have to perform such an important function?

What is tissue: biology will answer

According to the definition of the concept, tissue is a group of cells that are similar in structure and function. Not all living organisms are formed by similar structures. Thus, viruses are non-cellular forms of life, and all bacteria are unicellular.

Groups of specialized cells allow all physiological processes to be performed more efficiently. That is why highly organized living objects consist of organs. This fact is proved by biology. Cloth is just a structure consisting of cells and forming organs.

Fabrics of plants

What does the fabric consist of? Plant biology shows that not only from cells. Between them there is an intercellular substance serving as a link. Plant tissues are practically devoid of it.

They are represented by the following types:

1. Covering:

- skin - a living tissue with special structures - stomata, serving for gas exchange;

- cork is a dead tissue in which the metabolism is carried out with lenticles.

2. Basic - stores nutrients, carries out the process of photosynthesis, forms the basis of organs.

3. Mechanical - performs a supporting function.

4. Conductive - provides the ascending (water from the root) and descending (organic substances from the leaves) current substances.

5. Educational - in the process of division, restores the cells of any affected tissue, carrying out regeneration.

Animal Fabrics

A distinctive feature of this group of cells is the presence of a large amount of intercellular substance.

In animals, the following tissues are classified:

1. Epithelial - performs a protective function. It also forms glands and metabolizes. What is the formation of epithelial tissue? Its biology is simple: small, tightly fitting cells of various shapes.

2. Connective - consists of large cells and a large amount of intercellular substance. It is the basis of the whole organism. Her varieties are blood, bone, cartilaginous and fatty tissue.

3. Muscular - represented by separate fibers, capable of contraction - myofibrils. Thanks to them, it is possible to move the body in space and the movement of individual organs.

4. Nervous - connects the body with the environment, causes the presence of conditioned and congenital reflexes. It includes cells called neurons, and their processes are axons and dendrites. It is through them that information is transmitted from receptors of sensory systems to the brain, and from there to the working organs.

Interrelation of structure and functions

But most importantly, as science claims biology, tissue is a group of cells whose functions are conditioned by their structure.

For example, small, closely spaced epithelial cells, practically devoid of intercellular substance, look like a shield. With such features of the structure, the function is obvious - protection. The connective tissue is completely different. Because it creates the basis of all organs, there must be a lot of it. This explains the presence of large cells and a large amount of intercellular substance. Especially a lot of it in the blood. This substance is known by everyone as plasma. In it are the uniform elements. Erythrocytes - red blood cells - transport oxygen from the lungs to the organs and carbon dioxide in the opposite direction. Platelets - blood platelets, provide blood clotting. Leukocytes are colorless cells. They form the immune system, helping the body to withstand infectious diseases.

Fabrics and evolution

What is tissue, biology did not recognize immediately. After all, only with the invention of a light microscope, an amazing microscopic image of cells, and with it of tissues, was discovered to man.

Lower plants, which include algae, have no tissues. And even their multicellular representatives consisted of separate, unspecialized cells, not functionally interconnected. Further, with a change in climatic conditions, the first plant-born on land appeared on Earth. According to biology, tissue is a necessary condition for their survival in new conditions. At mosses and plauns first appeared the mechanical tissues necessary for their spatial arrangement. And after - and conducting. Such development led to the formation of real organs: root and shoot.

The most primitive multicellular animals also do not have real tissues. It is a representative of the type of the intestinal freshwater hydra. Its body is formed by specialized cells: epithelial, muscular, sexual, dermal, muscular, glandular, etc. But they do not form clumps, but are scattered throughout the body.

Thus, the appearance of tissues was the beginning of the complication of the structure of living organisms, which makes it possible to better adapt to any conditions.