Which type of cell is primarily responsible for defending the body against infections?

The type of cell primarily responsible for defending the body against infections is white blood cells. These cells, also known as leukocytes, play a crucial role in the immune system by identifying and attacking pathogens such as bacteria, viruses, and parasites.

White blood cells come in various types, including lymphocytes (which include T cells and B cells that are key in adaptive immunity) and phagocytes (which engulf and digest pathogens). When an infection occurs, white blood cells quickly mobilize to the site of infection to protect the body. They can also remember past infections, which allows for a faster and more effective response to future threats.

In contrast, red blood cells primarily function to transport oxygen throughout the body and platelets are involved in blood clotting. Nerve cells, or neurons, are responsible for transmitting signals in the nervous system and have no direct role in combating infections. This distinction highlights the specific and vital role of white blood cells in maintaining the body's health and defense mechanisms.