Final answer:
Brain cells begin to die within five minutes of oxygen deprivation, and death may occur within ten minutes. However, in cases of cold-water drowning, survival without oxygen can be longer, possibly up to an hour for the young. Permanent cell damage or death can also happen over the course of a few hours, such as in a stroke.
Step-by-step explanation:
Cells start to die when they are deprived of oxygen because oxygen is crucial for the production of adenosine triphosphate (ATP), which is the energy currency of the cell. Brain cells are particularly vulnerable to oxygen deprivation.
Brain damage is likely to occur within five minutes without oxygen, and death is likely within ten minutes. In some exceptional cases, such as in instances of cold-water drowning, the brain may survive without oxygen for a longer period, potentially up to an hour in young individuals.
It's important to note that permanent cell damage or death could also result from oxygen deprivation over a few hours, such as during a stroke. In cases of carbon monoxide poisoning, administering oxygen can significantly reduce the half-life of carbon monoxide in the blood and speed up recovery.
Overall, oxygen is indispensable for cellular respiration, and its absence leads to critical consequences for the cells and the organism as a whole.