Abstract
Hemoglobin is not merely a protein that carries oxygen from the lungs to the tissues, but a “smart” carrier that adapts to the needs of the body. This article examines and analyzes its two main mechanisms. The first is cooperativity: the hemoglobin tetramer shifts between the T and R conformational states, and the binding of one O₂ molecule facilitates the binding of subsequent O₂ molecules. The resulting sigmoid dissociation curve ensures full saturation of the blood in the lungs and efficient release of oxygen in the tissues. The second is the Bohr effect: H⁺ ions and CO₂ reduce the affinity of hemoglobin for O₂ and enhance O₂ delivery to metabolically active tissues. The article also discusses the clinical significance of these mechanisms, including adaptation to high altitude, acidosis and alkalosis, and the transfusion of stored blood.