Within the urinary system, the acid in the urine keeps most areas sterile; the outer region of the urethra, however harbors normal biota such as nonhemolytic streptococci, staphylococci, corynebacteria, and lactobacteria. Urinary system defenses include; mucous secretions that keeps things from attaching to the walls of the urinary tract but instead stick to it, Flushing action of urine, Desquamation of the epithelial cells, Acidity of the urine, antibacterial proteins in the urine which are lysozyme, and lactoferrin, and also the secretory IgA specific for previously encountered organisms.