Contrary to popular belief, human death is more of a process than a singular event. We often ascribe the cause of death to a condition or illness or trauma, but in reality, the final cause of every human death is a condition called cerebral hypoxia or cerebral ischemia. To put it simply, all human death has been the direct result of oxygen deprivation to the brain cells.
Cerebral hypoxia is rarely mentioned as a cause of human death, outside of specific traumas such as drowning or suffocation. When doctors speak of causes of human death, they often refer to the conditions which led to the deprivation of oxygen. The causes of death are often listed in a specific order of events. A cancer patient's cause of death may be listed as cerebral hypoxia, caused by pulmonary edema, caused by pervasive lung cancer. It may be acceptable to say a patient's death was caused by cancer or heart disease or severe trauma, but the real death is caused by complications of those conditions.
The function of the body's circulatory and respiratory system is to deliver a fresh supply of oxygen and nutrients to all of the cells, but the brain is an especially needy organ. The brain requires nearly a full 25% of the body's blood supply to function normally. When a disease compromises the blood's ability to deliver oxygen, the body begins to prioritize which organs receive the remaining healthy cells. As a disease progresses, the brain is often the last major organ besides the heart to feel the effects of the compromised blood cells.
Even a human death caused by sudden trauma is ultimately a case of cerebral hypoxia. The loss of blood caused by a bullet or knife wound reduces the amount of oxygen reaching the brain. If this proper balance is not restored, the heart and lungs may fail and the brain will literally begin to suffocate. After several minutes of total oxygen deprivation, the brain may not be able to recover any meaningful function. The autonomic system controlling the heart and lungs fails next, leading to the ultimate cause of all human death – oxygen deprivation of the brain cells.