RESPIRATORY PATHWAYS BECOME IRRITATED AND BRONCHIOLES CONSTRICT.

RESPIRATORY PATHWAYS BECOME INFECTED,RESULTING IN MUCUS BEING PRODUCED AND COUGHING.

ALVEOLI BREAK DOWN, WHICH MEANS IT CAN'T EXCHANGE GASES AS WELL.

INFECTION OF THE LUNGS, THAT CAUSES ALVEOLI TO COLLECT MUCUS MATERIAL.

A SPECIFIC BACTERIUM INFECTS THE LUNGS.

UNCONTROLLED CELL GROWTH IN LUNG TISSUE CAN LEAD TO A PERSISTENT COUGH.