Air travels from the external environment all the way through to your alveoli, where blood meets up with it through the capillaries. Blood exchange occurs here. The process of which a person takes one breath is called the respiratory cycle.
First, air enters your body either through your nose or your mouth, where it is then held in your nasal cavity/oral cavity. Once inside the nasal cavity, the air passes through the nasal conchae. As it travels, the air makes rapid swirls of movement in order to cause small particles in the air to stick to mucus. It is also humidified, filtered, and warmed.
The pharynx is a pathway in which both air and food travel, henceforth it is an important passage for the digestive and respiratory tracts. The pharynx is divided into three different parts-- the nasopharynx, the oropharynx, and the laryngopharynx. The nasopharynx is located at the back of the nasal cavity, and it is the uppermost part of the pharynx. In between the nasopharynx and the laryngopharynx is the oropharynx, which extends between the soft palate and the base of the tongue. The laryngopharynx is the extension of tissue between the hyoid and the entrance to the esophagus. It is the lowermost part of the pharynx and is the main entrance to the digestive tract.
After the air has passed through the pharynx, it then proceeds through to the larynx where it comes into contact with the glottis, a narrow opening that leads into the trachea. The larynx is also known as your voice box, from which sound is produced. Many structures within your larynx include the epiglottis (above the glottis), vocal cords,
Air travels through the trachea before it reaches the lungs. The trachea can also be referred to as the windpipe. It attaches to the cartilage located in your throat, from where it then travels downward before it breaks off into two primary bronchi.
There are two primary bronchi that branch off from the trachea. These structures are referred to as the right and left primary bronchi. Their layout is very similar to that of the trachea, with C-shaped rings encircling them to give them their structure, as well as cartilage to make it more easily moveable. The primary bronchi branch off into what is known as the bronchial tree, where air passes through the secondary bronchi which enters the lobes within the lungs. These bronchi are even more flexible than the primary. After air passes through the secondary bronchi, it then reaches the tertiary bronchi, which are even smaller pathways.
Bronchioles are the finest conducting pathways within the respiratory system. These bronchioles are the last passageway for air before it reaches the alveoli, where it then is combined with blood that is first pumped back to the heart, and then circulated throughout the rest of the body.
The alveoli are the areas within the lungs where the oxygen is transferred into the blood in exchange for carbon dioxide. In other words, this is where the gas exchange takes place. The air travels through the alveolar ducts into the alveolar sac where it is met with capillary networks. Air is diffused into the blood through a complicated series of chemical reactions. This is how fresh air replaces the air that has already been used. People with pneumoconiosis have trouble breathing due to coal dust building up in the alveoli, which clogs the alveolar sacs. This makes it harder to breath because blood cannot get a sufficient concentration of oxygen to receive nutrients.