Final answer:
The main function of white blood cells is to defend the body against infectious agents such as bacteria, viruses, and fungi, mainly through the process of phagocytosis.
Step-by-step explanation:
Main Function of White Blood Cells.The main function of white blood cells (WBCs), or leukocytes, is to defend the body against infectious agents such as fungi, bacteria, and viruses. These cells are a crucial part of the body's immune system. There are several types of white blood cells, and each plays a specific role in the immune response. For example, phagocytes, a type of white blood cell, are responsible for engulfing and destroying pathogens through a process known as phagocytosis. They travel to areas of inflammation to carry out this process, thereby helping to protect the body from infection and to clean up dead cells and other debris. While red blood cells primarily transport oxygen and nutrients, white blood cells are focused on the body's defense mechanisms. Unlike red blood cells, which have the protein hemoglobin for carrying oxygen, white blood cells circulate in the blood to detect and respond to foreign invaders. Furthermore, platelets play a different role; they are involved in forming clots to seal broken blood vessels and stop bleeding.