Final answer:
The primary function of tears and blinking in the immune system's first line of defense is pathogen elimination.
Step-by-step explanation:
The primary function of tears and blinking in the immune system's first line of defense is pathogen elimination. Regions of the body that are not protected by skin, such as the eyes, have tear production and blinking as a defense mechanism to trap and rinse away pathogens. Tears contain antibodies, such as immunoglobulin A (IgA), which help neutralize pathogens and prevent infection. Blinking also helps to keep the eyes moist and flush out any debris or pathogens that may come into contact with the eyes.