October 18, 2021
Blood (lat. Sanguis) is a red, opaque and thick liquid, with a special smell and salty taste. It flows through the body's cardiovascular system and carries nutrients and oxygen through the body. The total amount of blood in the body of an adult is 5-6 liters, which is about 8% of the total body weight. Blood consists of blood plasma, blood cells - erythrocytes, leukocytes and platelets - platelets. Blood is functionally the most important body fluid in humans. Blood is an endogenous body fluid unique to vertebrates. Lymph, another body fluid, is formed from the blood and flows into it. Blood belongs to the liquid connective tissues of mesodermal origin, which means that it has a large amount of intercellular connective substance created by the connective tissue cells themselves and immersed in it. Blood is part of the circulatory system. Blood is a fluid tissue that fills the heart and blood vessels and consists of two parts: a liquid called blood plasma and blood cells that float in the blood plasma and are made up of red blood cells (erythrocytes), white blood cells (leukocytes) and platelets (platelets). The ratio of blood plasma volume and blood cells in healthy people is constant. The volume of cellular elements is slightly smaller than the volume of plasma and it is 42 - 45%, and blood plasma 55 - 58% of the total blood volume. Blood cell volume in men is slightly higher than in women. The roles of blood are numerous. Blood serves the function of breathing, ie. for the transfer of oxygen and carbon dioxide, then for the transfer of nutrients, waste products, hormones, enzymes, vitamins, etc. Its role is also the regulation of the volume of body fluids, the regulation of acid-base balance, and the regulation of body temperature, and it also has a great protective role. Blood flows through the body in a closed system of tubes and blood vessels, which consists of arteries, veins and capillaries. In the chemical composition of the blood, the most important ingredients are: proteins (60 - 80 g / L), triglycerides (0.8 - 2.00 μmol / L), fibrinogen (2 - 4 g / L), sodium (135 - 151 μmol / L) ), cholesterol (3.5 - 6.7 μmol / L), glucose (4.2 - 6.4 μmol / L), urea (1.7 - 7.6 μmol / L), potassium (3.8 - 5.5 μmol / L), calcium (2.2 - 2.7 μmol / L) and bilirubin (4 - 20 μmol / L).