Smoking impairs the ciliated cells of the middle portion of the respiratory tract. Many analgesic drugs (painkillers) impair peristalsis (the churning motion of the digestive tract). The result of either of these activities leads to an increased risk of infection in their respective areas. Why?

Explanation:

The impairment of ciliated cells due to smoking causes an adverse effect on the respiratory track. This action reduces the efficiency and performance of the said track,thereby exposing it to infections and diseases. Little infection which the respiratory track would have been able to resist will become chronic due to the weakening of the ciliate cell.

Same applies to the digestive system the intake of painkillers do impair peristalsis.While peristalsis is the contraction and relacation of the stomach muscles during digestion . The intake of pain killer weaken this action and reduces the efficiency of the stomach wall, there by making it vulnerable to infections which are not an issue before.

experiments.

surveys.

questionnaires.

interviews.

case studies.

participant and non-participant observation.

observational trials.

studies using the delphi method.

the first one is d and the second a