Hemoglobin - ferrous respiratory pigment in the blood of vertebrates and many invertebrates engaged in the transport of oxygen from the respiratory organs to the body tissues. In the blood of vertebrates and some invertebrates hemoglobin contained within red blood cells in a dissolved condition.
The hemoglobin molecule vertebrates consists of protein globin and iron rich group - heme. The composition includes four heme protoporphyrinogen rings, each of which contains the atom ferrous iron. Molecular weight of hemoglobin, 66 000 - 68 000. The physiological function of hemoglobin as a carrier of oxygen is based on its ability reversible to bind oxygen, depending on the concentration of the latter in the blood. In the presence of oxygen iron heme associates one molecule of oxygen, with hemoglobin turns into oxyhemoglobin. At interaction of hemoglobin with carbon monoxide (for example, if poisoning this gas) produced a more stable complex - carboxyhemoglobin.
Decay products of hemoglobin are numerous zhelezomargantsevye complexes. Thus there is a complete separation of heme from protein (chromoprotein); this separation flows with the conversion of iron in the trivalent form. Get zhelezorudnye called Eminem, and its compounds - kementerian.
Usually a large part of hemoglobin in red blood cells is hemoglobin A, or normal hemoglobin adult. In congenital anomalies and diseases of blood-forming machine in red blood cells appear abnormal hemoglobins. It is observed, for example, sickle cell anemia (see Anemia in children), thalassemia (see), congenital methemoglobinemia (see).
Technique of determination of hemoglobin in the blood - see the Blood.

Hemoglobin performs in the body of the role of the carrier of oxygen and participates in the transport of carbon dioxide.
Hemoglobin is a complex molecule (molecular weight 68 800). It consists of a protein globin and four heme molecules. The heme molecule that contains atoms of iron, has the ability to attach and give oxygen molecule. This valence iron, joined oxygen is not changed, i.e. the bivalent iron remains.
If you handle the hemoglobin solution of hydrochloric acid, globin cleaved heme. Engaging in connection with the hydrochloric acid, it becomes geminus (Ca34H32N4O4FeCl), forming crystals characteristic shape. Test for education hemin is to prove the presence of blood in the forensic medical research.

Fig. 5. Absorption spectra of oxyhemoglobin (top) and hemoglobin.

Part of the heme molecule consists of four pyrrole rings (two of them have the character of alkali, and two - acid). The iron atom in the subject, connects with heme protein part globina. If heme iron atom loses, and Pirogova its structure is retained, it turns out hematoporphyrin. This substance in large quantities is formed in the body when some poisoning or violations of currency and may be released through the urine.
Heme is active, or the so-called prosthetic, a group of hemoglobin, and globin - protein media heme. Hemoglobin, absorbing oxygen into oxyhemoglobin (denoted by the symbol HbO2). Oxyhemoglobin, who gave oxygen, called restored, or reduced hemoglobin (Hb). Oxyhemoglobin, hemoglobin, and some other compounds, and derivatives of hemoglobin give the characteristic absorption bands of the rays of the spectrum. So, passing a beam of light through a solution of oxyhemoglobin, you may find two characteristic dark absorption bands in the yellow-green region of the spectrum between Frauenhofer lines D and E. For the restored hemoglobin one characteristic broad absorption band in the yellow-green region of the spectrum (Fig. 5).
Oxyhemoglobin is slightly different in color from haemoglobin, so arterial blood containing the oxyhemoglobin, has bright red color, while the more vivid, full happened its saturation by oxygen. Venous blood, containing a large number of recovered hemoglobin, is dark-cherry colour.
Much greater absorption of light rays with a wavelength of 620-680 MMK hemoglobin in comparison with oxyhemoglobin formed the basis of a technique of measuring the oxygen saturation of blood - oksiginatsii. With this method, the ear or the cell with blood Shine a small electric lamp and is determined using solar cells intensity luminous flux specified length of waves passing through the fabric of the ear or a cell with blood. According to the testimony of solar cells determine the degree of saturation of hemoglobin oxygen.
The blood of adults contains on average 14-15% of hemoglobin (men and 13.5-16%, in women of 12.5-14.5%). The total content of hemoglobin is approximately 700,
In the embryonic period in human blood are different types of hemoglobin, characterized by the ability to attach oxygen and some other chemical properties. For identifying and separating different types of hemoglobin use the methods of measurement of optical density of solutions of hemoglobin before and after denaturation his caustic alkali. Different types of hemoglobin conventionally denoted НbА, HbF, НbР. Hemoglobin NIR occurs only in the first 7-12 weeks of fetal development of the embryo. On the 9th week appears in the blood of the fetus hemoglobin HbF and hemoglobin adults НbА. Essentially important is the fact that fetal hemoglobin HbF has a higher affinity for oxygen and can be satisfied by 60% with the high voltage of oxygen, when the hemoglobin mother is saturated only 30%. Different species of vertebrates there are differences in the structure of hemoglobin. Heme different types of hemoglobin in this same glubiny also differ in their amino acid composition.

In the body constantly synthesis and breakdown of hemoglobin associated with the formation and destruction of red blood cells. The synthesis of hemoglobin committed erythroblastic red bone marrow. At destruction of red blood cells, which occurs in the reticulo-endothelial system, mainly in the liver and spleen, from red blood cells goes hemoglobin. In the result of detachment from haem iron and subsequent oxidation forms of hemoglobin pigment bilirubin, which is then excreted with jelchew in intestine, where it turns into stercobilin and urobilin that are excreted in the feces and urine. For the day is destroyed and transformed into bile pigments about 8 grams of hemoglobin, i.e. slightly more than 1 %.
In humans and animals can be formed and other compounds of hemoglobin, the spectral analysis being discovered characteristic absorption spectra. Among these compounds hemoglobin are methemoglobin and carboxyhemoglobin. These substances are formed as a result of some poisoning.
Methemoglobin (MetHb) is a strong connection hemoglobin oxygen; in the formation of methemoglobin change the valence iron: bivalent iron, which is part of the hemoglobin molecule, turning into trivalent. In case of accumulation in the blood of large quantities of methemoglobin the delivery of oxygen to tissues becomes impossible and death by suffocation.
Methemoglobin different from hemoglobin brown color and the presence of the absorption bands in the red part of the spectrum. Methemoglobin is formed under the action of strong oxidizing agents: ferricyanide (red blood salt), potassium permanganate, amyl - and propylnitrate, aniline, bertoletti salt, fenatsetina.
The carboxyhemoglobin (HbСО) is a compound hemoglobin iron with carbon monoxide (CO) - carbon monoxide. This connection about 150-300 times stronger than the connection of hemoglobin oxygen. Therefore, the impurity even 0.1% of the carbon monoxide in the air we breathe leads to the fact that 80% of hemoglobin are linked to carbon monoxide and not add oxygen, which is dangerous for life.
Weak carbon monoxide poisoning is a reversible process. When breathing the fresh air WITH gradually looses one of carboxyhemoglobin and outstanding.
Inhalation of pure oxygen increases the rate of splitting of carboxyhemoglobin in 20 times. In severe cases of poisoning need artificial breathing gas mixture with 95% of the content of O2 and 5% CO2, and a blood transfusion.
Myoglobin. In skeletal and cardiac muscle is the muscle hemoglobin called myoglobin. It enzymes - hem - identical to the same group of hemoglobin, a protein part - globin - has a lower molecular weight of the protein hemoglobin.
Myoglobin person is able to link up to 14% of the total number of oxygen in the body. This property plays an important role in supplying oxygen to the working muscles. If if muscles blood capillaries it is compressed and blood flow in some areas muscles stops, yet due to the presence of oxygen, associated with myoglobin, for some time saved supply muscle fibers oxygen.