Particulates Aerosol Clearance in Our LUNGS and its LIMITATION

The in built ‘air cleaning device’ of our body tackles introducing of particulate aerosol into there stages.

The first segment will be via irritant receptors at nose and bifurcation of large bronchi. At this stage the aerosols entry will trigger reflex of sneezing and coughing. The constriction of the bronchi will also limit further penetration.

The next stage will be Mucociliary Escalator referring to passage which runs from runs from nasal passage to trachebronchial tree. Aerosols transported along these route will be trapped by mucuous lining the airway.  The mucus is produced by specialized cells called goblet cells and is constantly being moved upward toward the throat by tiny hair-like structures called cilia. The cilia move the mucus along the respiratory tract and eventually push it up to the pharynx, where it can be swallowed or coughed up and expelled.

The final stage will be in the deep lung. There are no cilia in the alveoli and particles may be retained for a long period (months or even years). Although there are no cilia in the alveoli there are phagocytes (a range of different white blood cells that engulf and digest the deposited particles) which travel throughout the alveoli. One important type of phagocytic cells in humans are macrophage cells. Having taken up the particle the phagocyte or macrophage transports it from the alveoli either to the mucociliary escalator or via the lymphatic system.

Macrophages are specialized immune cells that play an important role in protecting the lungs from infection and inflammation. They help to clear out debris, bacteria, and other foreign particles that enter the lungs in the region of alveoli.

However, the macrophages have its limitation to certain type of particulate aerosols. One good example will be crystalline silica.

Silica particles are very small and have a large surface area relative to their size. They also have a very high affinity for water, which causes them to stick together and form agglomerates or clusters. These agglomerates are too large for macrophages to engulf and are not effectively cleared from the lungs.

However, the macrophages have its limitation to certain type of particulate aerosols. One good example will be crystalline silica.

Silica particles are very small and have a large surface area relative to their size. They also have a very high affinity for water, which causes them to stick together and form agglomerates or clusters. These agglomerates are too large for macrophages to engulf and are not effectively cleared from the lungs.

Silica particles are very small and have a large surface area relative to their size. They also have a very high affinity for water, which causes them to stick together and form agglomerates or clusters. These agglomerates are too large for macrophages to engulf and are not effectively cleared from the lungs. Other type of aerosols are asbestos fibre, carbon nanotubes, diesel combustion aerosols, metal fumes and ultra fine particulates.