Mucus occurs in both the respiratory and digestive tracts. What is its main immunological function?

physically trapping pathogens

Explanation:

Mucus is a thick slippery aqueous secretion that is secreted by the mucus membrane present in our body. The major production of mucus is by mucous gland.  

The mucus in the digestive and respiratory gland helps in trapping the pathogen which comes inside the body through food or air. Mucus also contains a large amount of IgA antibodies which is called secretory antibody.

This antibody binds to the antigen and prevent it from invading the body tissue. Therefore mucus helps in trapping the pathogens.

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