What term describes the process by which phagocytes engulf and destroy foreign substances?

Phagocytosis is the process by which phagocytes, a type of immune cell, engulf and digest foreign substances, such as bacteria or dead cells. During this process, the phagocyte extends its membrane around the target and internalizes it, forming a vesicle known as a phagosome. This vesicle then typically fuses with a lysosome, where enzymes break down the engulfed material. This is a crucial mechanism in the immune response, as it helps to eliminate pathogens and debris, maintaining the body's defense against infections.

Endocytosis refers to the general process of cells taking in material from the external environment but encompasses various forms, including pinocytosis and receptor-mediated endocytosis, not specifically targeting the engulfment of larger particles like phagocytosis does.

Exocytosis is the opposite process, where materials are expelled from a cell, usually involving the fusion of vesicles with the cell membrane to release contents outside.

Cellular respiration is a metabolic process that converts biochemical energy from nutrients into ATP and does not involve the engulfment of foreign substances.

Thus, the term that most accurately describes the specific action of phagocytes is phagocytosis.