How long can the human brain typically survive without oxygenated blood?

The human brain is highly dependent on a continuous supply of oxygenated blood to function properly. Typically, brain cells begin to suffer damage within a few minutes of oxygen deprivation. The critical time frame is often cited as around 4 to 5 minutes; beyond this period, irreversible brain damage can occur due to the lack of oxygen, which is essential for cellular metabolism and survival. While there are exceptional cases where some individuals have survived longer periods due to various factors, the 4 to 5-minute timeframe is widely accepted in medical literature for the onset of severe impairment and potential irreversible damage. This threshold highlights the importance of prompt medical response in situations of cardiac arrest or other emergencies where blood flow might be compromised.