What are the four types of hypoxia?

• A. Hypemic, Histotoxic, Hypoxic, Stagnant
• B. Hypoxic, Anemic, Carboxyhemic, Ischemic
• C. Hypoxic only
• D. All types of oxygen therapy

Answer: (A)

The question tests understanding that hypoxia can arise from four distinct mechanisms affecting how oxygen is carried to and used by tissues. Those mechanisms are: hypoxic hypoxia (insufficient oxygen reaching the blood, as at high altitude or with lung problems), hypemic hypoxia (the blood’s oxygen-carrying capacity is reduced, as in anemia or carbon monoxide poisoning), stagnant hypoxia (blood flow to tissues is too slow or blocked), and histotoxic hypoxia (cells can’t utilize oxygen due to toxins). The four terms that name these mechanisms are hypemic, histotoxic, hypoxic, and stagnant, which is why that option is the correct one.

The other choices blend or rename these mechanisms in ways that don’t align with the standard four categories (for example, using ischemic or carboxyhemic in place of one of the core types, or including something irrelevant like oxygen therapy).