that organism ??? ??? ??? pathogen a microorganism that causes a disease in humans ??? ??? ??? Peyer's patches located on the walls of the ileum; work with the immune system to protect against the entry of pathogens through the digestive system ??? ??? ??? phagocyte a large white blood cell that can destroy substances such as cell debris, dust, pollen, and pathogens by the process of phagocytosis