Which condition would MOST likely affect the entire brain?

• A. Reduced Blood Supply To The Left Hemisphere
• B. Ruptured Cerebral Artery In The Occipital Lobe
• C. Respiratory Failure Or Cardiopulmonary Arrest
• D. Blocked Cerebral Artery In The Frontal Lobe

Answer: (C)

The main idea here is that only a systemic disruption in oxygen delivery or blood flow can affect the whole brain, while problems in a single artery or a single brain region produce deficits limited to that area’s functions. The brain is highly sensitive to oxygen deprivation and requires a continuous blood supply; when respiratory failure or cardiopulmonary arrest occurs, both circulation and oxygen delivery collapse, leading to widespread neuronal dysfunction across both hemispheres. In contrast, reduced blood flow to only one hemisphere, rupture in a specific lobe, or a blockage in an artery supplying a particular region causes focal deficits—affecting functions governed by that area—rather than the entire brain. Thus, respiratory failure or cardiopulmonary arrest would most likely impact the entire brain.