Certified Transport Registered Nurse Certification Practice Exam

What is an example of a histotoxic agent that can interfere with oxygen utilization in the body?

1. Cyanide

2. Carbon monoxide

3. Alcohol

4. All of the above

The correct answer is: All of the above

Histotoxic agents are substances that impede the body's ability to utilize oxygen at the cellular level, often by interfering with the biochemical pathways involved in aerobic respiration. Cyanide is a potent histotoxic agent because it inhibits cytochrome c oxidase in the mitochondrial electron transport chain, effectively blocking the use of oxygen in cells, even when it is available. This results in the cessation of aerobic metabolism and shifts cells toward anaerobic metabolism, leading to tissue hypoxia. Carbon monoxide, while often discussed in terms of hypoxia from displacement of oxygen, acts as a histotoxic agent by binding to hemoglobin with a much higher affinity than oxygen. This binding reduces the oxygen-carrying capacity of blood and also disrupts cellular oxygen utilization due to its action at the mitochondrial level, similar to cyanide. Alcohol also acts as a histotoxic agent because it can disrupt oxidative phosphorylation in the mitochondria and affect the metabolism of various substrates. High levels of alcohol can impair the ability of cells to utilize oxygen, leading to cellular dysfunction and potentially contributing to metabolic stress. Combining these agents illustrates their common characteristic of hindering oxygen utilization in the body, making it accurate to state that all listed agents are examples of histotoxic agents affecting cellular respiration. This understanding is