MCOLES State Licensing Practice Exam

How long can cardiac and brain cells survive without oxygen?

1. 2-4 seconds

2. 4-6 seconds

3. 6-8 seconds

4. 10-12 seconds

The correct answer is: 4-6 seconds

Cardiac and brain cells are particularly sensitive to the absence of oxygen because they require a continuous supply to meet their high metabolic demands. The correct answer indicates that these cells can only survive for a very short time without the delivery of oxygen, specifically around 4 to 6 seconds, before irreversible damage begins to occur. The brain, for example, starts to sustain damage within just a few minutes of oxygen deprivation, but the immediate survival threshold is extremely limited. Cardiac cells are also deeply affected by a lack of oxygen, resulting in the potential for heart tissue damage or death if blood flow isn't restored quickly. Understanding the precise timeframe is critical for emergency responders and medical personnel, as it highlights the urgency of restoring oxygen supply during a medical crisis involving cardiac or cerebral function.