Final answer:
During an infection, white blood cells called phagocytes engulf pathogens through phagocytosis to form a phagosome, which fuses with a lysosome to create a phagolysosome where the pathogen is killed and digested. The remnants are then excreted, clearing the infection.
Step-by-step explanation:
White Blood Cells and Phagocytosis
When pathogens enter the body, an inflammatory response is triggered, and white blood cells, specifically phagocytes like macrophages and neutrophils, travel to the infected tissue. The purpose of this process, known as phagocytosis, is for the phagocytes to engulf the pathogen, forming a phagosome. This phagosome then fuses with a lysosome to create a phagolysosome, where hydrolytic enzymes and acids from the lysosome kill and digest the pathogen. Finally, the remains of the pathogen are excreted from the cell through exocytosis, effectively clearing the infection from the body.
During an infection, the extravasation of white blood cells allows them to leave the bloodstream through transendothelial migration and move towards the site of infection using amoeboid locomotion. The destruction of pathogens by phagocytes is a key aspect of the innate immune system's rapid response to prevent the spread of infection and aid in the recovery of the tissue affected by the invading organisms. It is important to note that while many pathogens are successfully destroyed by this process, some, such as Mycobacterium tuberculosis, have developed mechanisms to resist digestion and survive within phagocytes.