Many bacteria that enter the circulatory system are engulfed and destroyed by:
A. plasma.
B. platelets.
C. pinocytic red blood cells.
D. phagocytic white blood cells.
Phagocytic white blood cells engulf bacteria much like an ameba engulfs paramecium. They are involved in our second line of defense against harmful pathogens. The first line is protective barriers meant to prevent the pathogens from entering our body such as skin, tears, and mucus. If the phagocytes can't destroy all bacteria, then the third line of defense goes into action, namely our immune system, where antibodies are made to fight the invading pathogen.