Advanced Patient Assessment Practice Exam

Which type of white blood cell is most prevalent in the circulating blood?

1. Eosinophil

2. Monocyte

3. Neutrophil

4. Lymphocyte

The correct answer is: Neutrophil

Neutrophils are the most prevalent type of white blood cell found in circulating blood, typically accounting for about 50-70% of the total white blood cell count. They play a critical role in the immune response, particularly in the defense against bacterial infections. Neutrophils are part of the innate immune system and are among the first responders to sites of infection or inflammation. Their high prevalence ensures a swift response to pathogens, as they can quickly migrate to the affected area, where they engulf and destroy bacteria through a process called phagocytosis. Other types of white blood cells, such as eosinophils, monocytes, and lymphocytes, play important roles in various aspects of immunity and inflammation but occur in lower percentages in the blood. Eosinophils are primarily involved in battling parasitic infections and allergic reactions, while monocytes develop into macrophages that help in long-term immune responses. Lymphocytes, which include T cells and B cells, are crucial for adaptive immunity and memory responses but generally constitute a smaller fraction compared to neutrophils in circulation. This hierarchical structure of white blood cell types is essential for orchestrating effective immune responses to diverse threats.