How does the nasal cavity filter incoming air?

The nasal cavity filters incoming air through a process involving mucus, cilia, and the turbinates.

The nasal cavity is a complex structure that plays a crucial role in the respiratory system. It is primarily responsible for filtering, warming, and humidifying the air we breathe in before it reaches the lungs. This is achieved through a combination of physical structures and biological mechanisms.

The first line of defence in the nasal cavity is the nostril hairs, which trap larger particles such as dust and pollen. As the air travels further into the nasal cavity, it encounters the turbinates. These are bony structures covered in a soft tissue, which increase the surface area of the nasal cavity and create turbulence in the airflow. This turbulence allows for more effective warming and humidifying of the air, and also causes more particles to come into contact with the mucus-covered walls of the nasal cavity.

The mucus in the nasal cavity is a sticky substance that traps smaller particles that have been missed by the nostril hairs. This includes bacteria, viruses, and other potentially harmful microorganisms. The mucus also helps to humidify the air and contains enzymes that can neutralise some toxins.

The cilia are tiny hair-like structures that line the nasal cavity. They constantly beat in a coordinated manner, moving the mucus and trapped particles towards the throat. From here, the mucus is either swallowed into the stomach, where the acidic environment can kill many pathogens, or it is expelled from the body through coughing or sneezing.

In summary, the nasal cavity filters incoming air through a combination of physical structures and biological mechanisms. These include the nostril hairs, turbinates, mucus, and cilia, which work together to trap particles, humidify and warm the air, and move potentially harmful substances out of the body.