Cilia in the Respiratory Pathway
The cilia are the small hair-like structures found in the airway. They propel the mucus (fluid) that can trap the pathogens easily. This mucus layer of the respiratory pathway helps in catching the pathogens and prevents them from reaching the lungs of humans. The movement of cilia is very fast. They can beat up to a thousand times in a minute. The pathogens get trapped in the mucus and can be expelled outside in the form of a cough. The ciliary structures of the respiratory tract clear the mucus and the waste material from the upper and lower airway pathways. Cilia are organelles present on the apical surface of the epithelial cells. Each of the cilia is attached to the basal bodies that are derived from the centrioles. The cilia are formed by the bundle of the microtubules that are called axonemes. The cilia beat in a coordinated manner, referred to as a metachronous wave.
These alveolar macrophages are a kind of white blood cell found on the alveolar surface. These are also meant for the defense mechanism. These macrophages bind with the pathogens and kill them. Neutrophils are responsible for a defense mechanism; they fight with foreign particles and kill them.