Question

How do the protective mechanisms present in the respiratory tract help prevent diseases from developing?

Answer 1

By preventing the virus from reaching the lungs, where it can infect the body.

Explanation:

The trachea and bronchi are lined with a layer of mucus in order to trap pathogens and bar them from reaching the lungs. This mucus is then moved up the airway by the cilia of cells in the trachea to be coughed up or swallowed.

Here's a diagram of the cilia in the trachea:

The nasal cavity also has mucus in addition to hair to trap pathogens before they reach the lungs.

As a last line of defense, there are macrophages (white blood cells) present on the alveoli in the lungs to swallow up any pathogens that got past the mucus/hair defense.