What role do white blood cells play in the body?

White blood cells are a crucial component of the immune system, serving the primary function of defending the body against infections, pathogens, and diseases. These cells, also known as leukocytes, recognize and neutralize harmful organisms such as bacteria, viruses, and fungi, as well as malignant cells. They achieve this through a variety of mechanisms, including phagocytosis, where they engulf and digest invaders, and by producing antibodies that target specific pathogens.

Each type of white blood cell plays a unique role in the immune response; for example, lymphocytes (including B cells and T cells) are vital for adaptive immunity, while neutrophils and macrophages are key players in the innate immune response. The ability of white blood cells to remember past infections and respond more effectively upon re-exposure is essential for long-term immunity.

The other options do not accurately represent the functions of white blood cells. They do not produce hormones, nor are they part of the respiratory system, and they do not regulate blood sugar levels; these roles are carried out by other cells and systems in the body. Understanding the significant role of white blood cells helps highlight their importance in maintaining health and combating diseases.