Why does the brain need oxygen?

Most people who have studied firs aid know that, if breathing stops, it’s essential to restart it quickly. Frequently, when somebody is saved from suffocation, for example, breathing restarts but not soon enough. The victim survives and suffers irreparable brain damage. Of all the body’s organs, the brain cannot normally survive for more than four or five minutes without oxygen carried to it by the blood.

Other organs are not so delicate. Today, in what has become quite a commonplace operation, micro-surgeons reattach fingers, hands and complete limbs that have been served – usually it is wrapped in plastic and packed in ice to ensure this – it will eventually recover its functions.

The brain, however, consists of millions of cells, which are constantly active, while we are awake and asleep. The average blood cell as 350 million haemoglobin molecules, each holding four molecules of oxygen. The oxygen helps to provide energy for the chemical reactions of all living cells. IF the ever-active brain cells are starved of oxygen, they perish. Because the brain cells are closely linked and interact, when some cells die others and are doomed.

Until quite recently, doctors believed that oxygen starvation for just a few minutes would inevitably cause irreparable damage to the brain. A succession of freak survivals, cases in which swimmers were saved from drowning after being apparently dead for half an hour or more, made them revise their theories.

Nearly all these survivals were in cold water. Neurosurgeons know that cold stimulates a reflex action which slows the body’s metabolism. In some operations, the body temperature is deliberately reduced for this reason.  the swimmers’ case, cold water on their faces triggered the mammalian reflex, as it is known. Their metabolism slowed down, so that the brain and other vital organs needed less oxygen.

As specialist have observed, the brain begins to idle. When this happens, areas of the body such as the limbs give up their oxygen supply so that it can go where it is most wanted. Lifesavers and others should take note that, once the victim’s face is out of the water, the mammalian reflex stops. That is why it is essential to start resuscitation immediately.