Biological Chemistry - Berezov T. T., Korovkin B. F. 1998

Nervous Tissue
Metabolic Features of Nervous Tissue
Respiration

The Brain accounts for 2—3% of body mass. At the same time, oxygen consumption by the brain at physical rest reaches 20—25% of the total oxygen consumption of the entire body, and in children under 4 years of age, the brain consumes as much as 50% of the oxygen utilized by the whole Organism.

The consumption of various substances from the Blood by the brain, including oxygen, can be assessed by the arteriovenous difference. It has been established that while passing through the brain, blood loses about 8 vol.% of oxygen. Per 100 g of brain tissue, 53—54 ml of blood is supplied per minute. Consequently, 100 g of the brain consumes 3.7 ml of oxygen per minute, and the entire brain (1500 g) consumes 55.5 ml of oxygen*.

Gas Exchange in the brain is significantly higher than that in other Tissues; in particular, it exceeds the gas exchange of Muscle tissue by almost 20 times. The intensity of Respiration varies across different Regions of the brain. For instance, the respiration rate of White matter is twice as low as that of Gray matter (though white matter contains fewer Cells). Oxygen is consumed with particularly high intensity by the Cells of the Cerebral Cortex AND Cerebellum.

Oxygen uptake by the brain is significantly reduced during anesthesia. Conversely, the intensity of brain respiration increases with heightened functional activity.