Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What is the primary role of leukocytes in the immune response?

1. Transporting oxygen in blood

2. Producing hormones

3. Defending against pathogens

4. Regulating blood pressure

The correct answer is: Defending against pathogens

Leukocytes, also known as white blood cells, play a crucial role in the immune response by defending the body against pathogens such as bacteria, viruses, and parasites. They are an essential component of the immune system, as they identify and neutralize foreign invaders, helping to prevent infections and maintain overall health. When an infection occurs, leukocytes are activated and migrate to the site of infection. They can recognize pathogens through specific receptors and respond in various ways, including directly attacking the invaders, producing antibodies, or signaling other components of the immune system to take action. Different types of leukocytes, such as neutrophils, lymphocytes, and monocytes, each have specialized functions in targeting and eliminating threats. In contrast, transporting oxygen in blood is the primary function of red blood cells, while producing hormones is a role associated with endocrine glands rather than leukocytes. Regulating blood pressure typically involves cardiovascular systems and specific components like endothelial cells and smooth muscle, not leukocytes. Thus, the central function of leukocytes is firmly anchored in the immune response, making them vital for protecting the body from disease.