AEMCA Practice Exam

What best describes the mechanism of action of hydrogen cyanide as a chemical asphyxiate?

1. It uplifts oxygen levels in the body

2. It interferes with cellular respiration

3. It induces hyperventilation

4. It enhances blood flow

The correct answer is: It interferes with cellular respiration

Hydrogen cyanide functions as a chemical asphyxiate primarily by interfering with cellular respiration. It achieves this by inhibiting the enzyme cytochrome c oxidase, which is critical in the electron transport chain within mitochondria. This enzyme plays a crucial role in the final steps of aerobic respiration, where it facilitates the transfer of electrons to oxygen. When hydrogen cyanide binds to cytochrome c oxidase, it effectively blocks the utilization of oxygen by the cells despite its presence in the bloodstream. As a result, the cells cannot perform oxidative phosphorylation, leading to a state of severe hypoxia, where cells are unable to generate sufficient ATP. Consequently, vital organs are affected, resulting in cellular failure and death if exposure is significant and untreated. The other options do not accurately represent the mechanism of action of hydrogen cyanide. For instance, it does not uplift oxygen levels, induce hyperventilation, or enhance blood flow; instead, it directly disrupts the fundamental processes required for cells to utilize oxygen efficiently. Understanding this precise mechanism is key to recognizing the lethal effects of hydrogen cyanide exposure in various contexts, including industrial accidents or chemical warfare.