Blood is a biological fluid thatprovides organs and tissues with nutrients and oxygen. Together with the lymph it forms a system of circulating fluids in the body. Performs a number of vital functions: nutritional, excretory, protective, respiratory, mechanical, regulatory, thermoregulatory.
The composition of human blood with age significantlychanges. It should be said that children have a very intensive metabolism, so in their body it is much more than 1 kg of body weight in comparison with adults. On average, an adult has about five to six liters of this biological fluid.
The composition of the blood includes plasma (liquid part) anduniform elements (erythrocytes, leukocytes, platelets). The color of red blood cells depends on its color. Plasma, devoid of protein (fibrinogen), is called serum. This biological fluid has a slightly alkaline reaction.
Biochemical composition of blood - buffer systems. The main blood buffers are bicarbonate (7% of the total mass), phosphate (1%), protein (10%), hemoglobin and oxyhemoglobin (up to 81%), and acid (about 1%) system. The plasma is dominated by hydrocarbonate, phosphate, protein and acid, in erythrocytes - bicarbonate, phosphate, in hemoglobin - oxyhemoglobin and acid. The composition of the acidic buffer system is represented by organic acids (acetate, lactate, pyruvic, etc.) and their salts with strong bases. The most important are bicarbonate and hemoglobin buffer systems.
Chemical composition of blood. Blood is characterized by a constant chemical composition. Plasma is 55-60% of the total volume of blood and 90% consists of water. The dry residue is organic (9%) and mineral (1%) substances. The main organic substances are proteins, most of which are synthesized in the liver.
Protein composition of blood. The total protein content in mammalian blood ranges from 6 to 8%. About one hundred protein components of plasma are known. Conditionally they can be divided into three fractions: albumins, globulins and fibrinogen. Plasma proteins that remained after removal of fibrinogen are called serum blood proteins.
Albumins are involved in transportationmany nutritional and biologically active substances (carbohydrates, fatty acids, vitamins, inorganic ions, bilirubin). Participate in the regulation of water-mineral metabolism. Serum globulins are divided into three fractions of alpha, beta and gamma globulins. Globulins transport fatty acids, steroid hormones, fat-soluble vitamins, are immune bodies.
Carbohydrate blood composition. The plasma contains monos (glucose, fructose), glycogen, glucosamine, monophasic phosphates and other products of intermediate carbohydrate metabolism. Most of the carbohydrates are glucose. Glucose and other monoenzymes in the blood plasma are in free and protein-bound states. The content of bound glucose reaches 40-50% of the total carbohydrate content. Intermediate carbohydrate metabolites produce lactate acid, the content of which sharply increases after heavy physical exertion.
The concentration of glucose can vary with many pathological conditions. The phenomenon of hyperglycemia is characteristic of diabetes mellitus, hyperthyroidism, shock, anesthesia, fever.
Lipid composition of blood. Plasma contains up to 0.7% and more lipids. Lipids are in free and protein-bound states. The concentration of lipids in the plasma varies with pathology. So, with tuberculosis it can reach 3-10%.
Gas composition of blood. This biofluid contains oxygen (oxygen), carbon dioxide and nitrogen in free and bound states. For example, about 99.5-99.7% of oxygen is associated with hemoglobin, and 03-0.5% is in a free state.</ p>