anatomical barriers. innate immune system

acid anatomical anatomy barrier barriers bile biology blood bloodbrain body brain care chemical damage defense desquamation diagram digestive disease education epithelial eyes gastric graphic health healthcare human illustration immune immunity infection infographic innate internal intestine isolated liver lungs lysozyme medical medicine nasopharynx organ pathogen peristalsis physical protect protection saliva science skin skincare spleen stomach structure surfactant system tears tract treatment vector