Which type of blood cell is primarily responsible for immune defense and phagocytosis?

Leukocytes, also known as white blood cells, are the primary type of blood cell involved in immune defense and phagocytosis. They play a crucial role in the body's immune system by identifying and eliminating pathogens like bacteria, viruses, and other foreign substances. The leukocyte population includes various types of cells, such as neutrophils, monocytes, and lymphocytes, each of which has specific functions related to immune responses.

Phagocytosis, the process by which certain leukocytes engulf and digest cellular debris and pathogens, is primarily conducted by cells such as neutrophils and monocytes. These cells are adept at recognizing harmful invaders and initiating an immune response, helping to protect the body from infections and diseases.

In contrast, erythrocytes, or red blood cells, are primarily responsible for transporting oxygen from the lungs to tissues and returning carbon dioxide from the tissues to the lungs. Thrombocytes, or platelets, are involved in blood clotting and do not play a direct role in immune defense. Plasma cells, a type of B lymphocyte, are responsible for producing antibodies, but they are not directly involved in the phagocytosis process. Thus, leukocytes are the specific blood cells that execute immune defense functions