Which type of agent prevents the body from using oxygen?

Cyanide compounds are classified as agents that prevent the body from effectively using oxygen. They work by inhibiting an essential enzyme called cytochrome c oxidase in the electron transport chain, which is crucial for cellular respiration. This disruption impairs the cells' ability to utilize oxygen, even if it is present in the bloodstream. As a result, despite adequate oxygen levels, the body experiences a state of hypoxia, leading to potentially fatal consequences if exposure is significant.

In contrast, choking agents primarily impact the respiratory system by causing mechanical irritation or fluid buildup in the lungs, leading to suffocation rather than interfering with oxygen utilization at the cellular level. Blister agents mainly cause skin blisters and damage to mucous membranes, not directly affecting oxygen usage in the body. Nerve agents impair nerve function and can disrupt bodily processes, but their primary effect is not the prevention of oxygen use; instead, they interfere with neurotransmission and muscle control.