https://hyp.is/go?url=https%3A%2F%2Fbio.libretexts.org%2FCourses%2FManchester_Community_College_(MCC)%2FRemix_of_Openstax%253AMicrobiology_by_Parker_Schneegurt_et_al%2F13%253A_Innate_Nonspecific_Host_Defenses%2F13.01%253A_1st_Line_defense-_Physical_and_Chemical_Defenses&group=world