Correct Option
The correct option isTo filter out dust and particulate matter.
Explanation
The human respiratory system is equipped with natural defense mechanisms in the upper respiratory tract (specifically the nasal cavity) to condition inhaled air before it reaches the delicate tissues of the lungs. This conditioning involves filtration, warming, and humidification.
Option Analysis:
- To regulate the temperature of inhaled air. is Incorrect: The regulation of temperature (warming of inhaled air) is primarily performed by the extensive network of blood capillaries (vascular tissue) located in the nasal conchae or turbinates. While mucus aids in humidification, the fine hairs do not play a significant role in temperature regulation.
- To filter out dust and particulate matter. is Correct: The primary physiological function of the fine hairs (vibrissae) located at the entrance of the nasal cavity is to act as a coarse filter. They trap larger dust particles and foreign debris. The mucus lining the cavity traps smaller particulate matter, pollen, and microbes, preventing these impurities from entering the lower respiratory tract.
- To facilitate the diffusion of oxygen. is Incorrect: The diffusion of oxygen and carbon dioxide occurs across the respiratory membrane in the alveoli of the lungs. The nasal cavity serves as a conducting passage, not a site for gaseous exchange.
- To detect olfactory signals. is Incorrect: While the nasal cavity contains the olfactory epithelium responsible for detecting smell, this function is localized to a specific region of sensory cells. It is not the primary function of the general hair and mucus lining found throughout the nasal passage.
Key Takeaway:
The fine hairs (vibrissae) and mucus in the nasal cavity constitute the body's first line of defense against air pollution, functioning primarily to filter out dust and particulate matter from inhaled air.