What will happen if respiration and heartbeat are not reestablished after clinical death?

The correct answer identifies the concept of brain death, which is defined as the irreversible cessation of all brain activity, including in the brainstem. When respiration and heartbeat are not reestablished after clinical death, the lack of oxygen-rich blood flow leads to rapid brain cell death due to hypoxia. Within a short period, typically a few minutes, vital functions regulated by the brain, such as respiration and homeostasis, cease to function.

Brain death is distinct from other types of death because it specifically refers to the loss of brain function, despite the possibility that other physiological functions may continue for a time with mechanical support or artificial means, such as a ventilator. This highlights the critical relationship between brain function and the overall definition of death in medical and ethical contexts.

In contrast, biological death encompasses a broader category wherein all cellular processes stop due to irreversible damage; somatic death refers to the cessation of all bodily functions and is often used in a more general sense; postmortem cellular death describes cellular breakdown after somatic death without necessarily focusing on brain function.