Assertion: human body's system | /r/HasProperty | barrier
Facets:
Source sentences:
text: This system includes barriers to infection, such as skin and the mucus coating of the gut and airways; phagocytic cells that can ingest and digest foreign substances; and anti-microbrial proteins.
text: The whole system includes two kidneys, two ureters, the bladder, two sphincter muscles and the urethra.