Human blood consists of cells and liquidpart, or serum. The liquid part is a solution containing a certain amount of micro- and macronutrients, fats, carbohydrates and proteins. Blood cells are divided into three main groups, each of which has its own features of structure and function. Let's consider each of them more carefully.
Erythrocytes, or red blood cells
Erythrocytes are fairly large cells thathave a very characteristic form of a biconcave disk. Red corpuscles do not contain a nucleus - in its place is a molecule of hemoglobin. Hemoglobin is a rather complex compound that consists of the protein part and the ferrous iron atom. Erythrocytes form in the bone marrow.
Red blood cells have many functions:
- Gas exchange is one of the main functions of blood. Direct involvement in this process is taken by hemoglobin. In small pulmonary vessels, the blood is saturated with oxygen, which combines with the iron of hemoglobin. This relationship is reversible, so oxygen remains in the tissues and cells where it is needed. Simultaneously, when one oxygen atom is lost, hemoglobin combines with carbon dioxide, which is transferred to the lungs and released into the environment.
- In addition, on the surface of red blood cells there are specific polysaccharide molecules, or antigens, that determine the Rh factor and blood group.
White blood cells, or leukocytes
Leukocytes are a fairly large group of differentcells, the main function of which is to protect the body from infections, toxins and foreign bodies. These cells have a core, can change their outlines and pass through the tissues. They form in the bone marrow. Leukocytes are divided into several separate types:
- Neutrophils are a large group of leukocytes,having the ability to phagocytosis. In their cytoplasm contains a lot of granules, filled with enzymes and biologically active substances. When bacteria or viruses enter the body, the neutrophil moves to an alien cell, captures it and destroys it.
- Eosinophils are blood cells that perform a protective function, destroying pathogens by phagocytosis. They work in the mucous membrane of the respiratory tract, intestines and urinary system.
- Basophils are a small group of small oval cells that take part in the development of the inflammatory process and anaphylactic shock.
- Macrophages are cells that actively destroy virus particles and bacterial cells, but have granular aggregations in the cytoplasm.
- Monocytes - are characterized by a specific function, since they can either develop or, on the contrary, inhibit the inflammatory process.
- Lymphocytes are leukocytes responsible for the immune response. Their peculiarity lies in the ability to form resistance to those microorganisms that have already penetrated into human blood at least once.
Blood platelets, or platelets
Platelets are small, denuclearized human blood cells of oval or round shape. After activation, protrusions form on the outer membrane of the cell, as a result of which it resembles a star.
Platelets perform a number of rather important functions. Their main purpose is the formation of the so-called blood clot. The place of injury is the first to get the platelets, which under the influence of enzymes and hormones begin to stick together, forming a thrombus. This clot closes the wound and stops the bleeding. In addition, these blood cells are responsible for the integrity and stability of the vascular walls.
It can be said that blood is a rather complex and multifunctional type of human connective tissue, designed to maintain normal life activity.