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Connective tissue
Last reviewed: 20.11.2021
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Connective tissue (textus connectivus) is a large group of tissues, including the connective tissue itself (loose and dense fibrous), tissues with special properties (reticular, fatty), liquid (blood) and skeletal (bone and cartilaginous). These tissues perform many functions: supporting, mechanical (connective tissue proper, cartilage, bone), trophic (nutrient), protective (phagocytosis and transport of immunocompetent cells and antibodies). Connective tissues are formed from numerous cells and intercellular substance consisting of proteoglycans and glycoproteins (adhesive proteins), as well as various fibers (collagen, elastic, reticular).
All kinds of connective tissue are derived from the mesenchyme, which, in turn, is formed from the mesoderm
Cells of connective tissue
Fibroblasts are the main cells of connective tissue. They are spindle-shaped, from the surface of the fibroblasts thin short and long processes depart. The amount of fibroblasts in different types of connective tissue is different, especially many in loose fibrous connective tissue. Fibroblasts have an oval core filled with small chromatin blocks, a distinct nucleolus and a basophilic cytoplasm containing many free and attached ribosomes.
Fibrous connective tissue
Fibrous connective tissues include loose and dense fibrous connective tissues. Dense fibrous connective tissue, in turn, has two varieties - unformed and decorated dense connective tissue.
[7], [8], [9], [10], [11], [12]
Fabrics with special properties
To connective tissues with special properties are fat, reticular and mucous. They are located only in certain organs and parts of the body and are characterized by special features of the structure and peculiar functions.
Fabrics with special properties
Blood
Blood is a kind of connective tissue. Its intercellular substance is liquid - this is blood plasma. In the blood plasma there are ("floating") its cellular elements: erythrocytes, leukocytes, as well as platelets (blood plates). In a person with a body weight of 70 kg, an average of 5.0-5.5 liters of blood (this is 5-9% of the total body weight). The functions of blood are the transfer of oxygen and nutrients to organs and tissues and the removal of metabolic products from them.
Plasma of blood is a liquid that remains after removing from it the uniform elements - cells. It contains 90-93% water, 7-8% of various protein substances (albumins, globulins, lipoproteins, fibrinogen), 0.9% salts, 0.1% glucose. In the blood plasma there are also enzymes, hormones, vitamins and other substances necessary for the body. Proteins of plasma participate in the process of blood coagulation, ensure the constancy of its reaction (pH 7.36), pressure in the vessels, viscosity of the blood, prevent the accumulation of red blood cells. The blood plasma contains immunoglobulins (antibodies) that participate in the protective reactions of the body.
The blood glucose in a healthy person is 80-120 mg% (4.44-6.66 mmol / l). A sharp decrease in the amount of glucose (up to 2.22 mmol / L) leads to a sharp increase in the excitability of brain cells. A further decrease in the glucose level in the blood leads to a violation of breathing, circulation, consciousness and can be fatal to humans.