19. Innate Immunity

Which physical, nonspecific host defense mechanism is associated with the respiratory tract and trachea?

Mucus-secreting membranes are found in:

a. The urinary system

b. The digestive cavity

c. The respiratory passages

d. All of the above

Indicate which statements are true. Correct all false statements by changing the underlined words.

__________ The surface cells of mucous membranes are alive.