Respiratory epithelium is the tissue lining the mouth, nose, throat, and trachea. This lining acts as a barrier between the air coming into the body and the inner tissues of the respiratory mechanism, and it also serves to warm, clean and moisten the air in preparation for its arrival in the lungs. It is composed mainly of ciliated, goblet, and basal cells, each of which serves specific functions that support respiration. In the study of tissue types, respiratory epithelium is called ciliated pseudostratified columnar epithelium.
Epithelial tissue is one of the four types of tissue of the human body. It lines cavities and structures, and performs functions such as secretion, absorption and protection. Respiratory epithelium is epithelial tissue that is specialized to serve functions necessary in the respiratory tract. It lines the cavities of the body involved in respiration, serving as a barrier between air coming into the respiratory system and the inner tissues of the body. It also warms and cleans the air before it reaches the lungs, where oxygen from the air is absorbed into the bloodstream.
One important function of respiratory epithelium is to clean the air inhaled by the body before it reaches the lungs. The respiratory lining is covered in mucus, which serves to capture pollutants as they travel through the respiratory cavities. Once captured, pollutants are swept back toward the outside of the body by small, hair-like structures called cilia. These cilia are constantly beating in a wave-like motion that moves foreign objects up and out of the body.
Warming air from the outside world before it reaches the lungs is another important function of the lining. The respiratory epithelium that lines nasal passages is particularly blood-rich. As air passes through the nose, warmth from the blood passing through the blood vessels underneath the lining is transferred to the air. The warmed air then continues its path toward the lungs, where it will supply the blood with oxygen.
Respiratory epithelium is composed of three main cell types: ciliated, goblet, and basal. Ciliated cells produce the hair-like cilia that line the respiratory tract and serve to capture and remove pollutants from the system. Goblet cells secrete mucus, which moistens the epithelial tissue and also helps trap foreign particles moving through the respiratory tract. Basal cells are cells that will differentiate into other cell types when needed.
In the study of tissue types, respiratory epithelium is called ciliated pseudostratified columnar epithelium. This name serves to describe the characteristics and composition of respiratory epithelium. Psuedostratified refers to the cell structure of the tissue, which appears under microscopic visualization to be tightly stacked in a column-like arrangement. Ciliated refers to the cilia that grow out of the tissue and serve the important cleaning function described above.