Barcrofta Phenomenon

The Barcroft phenomenon is a physiological phenomenon consisting of an increase in the content of red blood cells and hemoglobin in the blood under conditions of hypoxia (oxygen starvation). This is a compensatory reaction of the body aimed at improving the delivery of oxygen to tissues when there is a lack of oxygen.

The phenomenon was first described by British physiologist Joseph Barcroft in 1925. He found that people and animals at high altitudes in mountains with reduced partial pressure of oxygen experienced a significant increase in the number of red blood cells and hemoglobin compared to being at sea level.

The mechanism of the Barcroft phenomenon is that under conditions of hypoxia, the kidneys begin to produce more erythropoietin, a hormone that stimulates hematopoiesis in the red bone marrow. This leads to increased maturation of red blood cells, increasing their number. There is also an increase in the hemoglobin content in each red blood cell.

Thus, the Barcroft phenomenon is an important adaptive mechanism that allows the body to maintain oxygen delivery to tissues under unfavorable conditions of oxygen deficiency. It is of great importance for survival at high altitudes and in some diseases accompanied by hypoxia.