The respiratory system consists of the nose, pharynx, larynx, trachea, bronchi and bronchioles and the lungs.
As air passes through the nasal cavities it is warmed and humidified, so that air that reaches the lungs is warmed and moist. The Nasal airways are lined with cilia and kept moist by mucous secretions. The combination of cilia and mucous helps to filter out solid particles from the air an Warm and moisten the air, which prevents damage to the delicate tissues that form the Respiratory System. The moisture in the nose helps to heat and humidify the air, increasing the amount of water vapor the air entering the lungs contains. This helps to keep the air entering the nose from drying out the lungs and other parts of our respiratory system. When air enters the respiratory system through the mouth, much less filtering is done. It is generally better to take in air through the nose.
The pharynx is also called the throat. As we saw in the digestive system, the epiglottis closes off the trachea when we swallow. Below the epiglottis is the larynx or voice box. This contains 2 vocal cords, which vibrate when air passes by them. With our tongue and lips we convert these vibrations into speech. The area at the top of the trachea, which contains the larynx, is called the glottis. The trachea or windpipe is made of muscle and elastic fibers with rings of cartilage. The cartilage prevents the tubes of the trachea from collapsing. The trachea is divided or branched into bronchi and then into smaller bronchioles. The bronchioles branch off into alveoli. These tubes are lined with mucous-secreting cells and tiny hairs called cilia. The mucous traps bacteria, dust and viruses. The cilia beat and create an upward current. This moves the mucous up and into the oesophagus. Here it goes to the stomach. When we clear our throats we force the mucous away from our vocal cords. It is used to get rid of irritants and excess mucous from our respiratory system.
The lungs are...