Most inspired particles such as dust fail to reach the lungs because of the
A abundant blood supply to nasal mucosa.
B ciliated mucous lining in the nose.
C porous structure of turbinate bones.
D action of the epiglottis.
The correct answer and explanation is:
The correct answer is B: ciliated mucous lining in the nose.
The nasal cavity plays an essential role in filtering, warming, and humidifying the air we breathe. The ciliated mucous lining in the nose is a primary defense mechanism that helps prevent inhalation of harmful particles, such as dust, bacteria, and other environmental contaminants. This lining is composed of mucus-producing cells and cilia, which are tiny hair-like structures that move in a coordinated fashion to trap and remove foreign particles from the respiratory system.
When dust or other particles enter the nasal passages, the sticky mucus in the lining traps them. The cilia then move in a sweeping motion to push the mucus, along with the trapped particles, toward the back of the throat, where it can be swallowed or expelled through coughing. This process is known as mucociliary clearance and is an essential defense against respiratory infections and irritants.
Option A, abundant blood supply to the nasal mucosa, also contributes to the warming and humidifying of the air but is not directly responsible for trapping particles. While the blood supply helps keep the nasal passages moist and supports the immune response, it does not actively filter or remove particles from the air.
Option C, the porous structure of turbinate bones, also plays a role in increasing the surface area of the nasal passages to enhance the warming and humidifying of the air, but it does not directly prevent dust particles from reaching the lungs.
Option D, the action of the epiglottis, is unrelated to the filtering of particles in the nose. The epiglottis functions to prevent food and liquid from entering the trachea and lungs during swallowing, but it does not play a role in filtering airborne particles.
Thus, the ciliated mucous lining in the nose is the primary defense against inhaled particles, ensuring that most harmful particles do not reach the lungs.