The interior of the nose is lined with mucous membrane, and most of the membrane is covered with minute hairlike projections called cilia. Moving in waves these cilia sweep out from the nasal passages the nasal mucus, which may contain pollen, dust, and bacteria from the air.he specialized structure of the head that serves both as the organ of smell and as the first segment of the respiratory apparatus. Air breathed in through the nose is warmed, humidified and filtered by the richly vascular mucous membrane.