Gas Exchange Structure

The respiratory system is a vital factor of gas exchange due to its structures. The structure provides an efficiency to the process. Gas exchange requires an efficient system because it is a process through which blood circulates around the body, collects oxygen, delivers the oxygen to the organs that require it and releases carbon dioxide. oxygen and carbon dioxide enter and exit the body in opposite directions across a respiratory surface area that supplies enough oxygen to allow the process to occur efficiently. The process begins when gases from the atmosphere, including oxygen, enter the body through either the nasal cavity, or the oral cavity. Afterwards, the oxygen enters the pharynx, a path that connects the nasal cavity and the trachea.
As the oxygen enters the lungs, the trachea divides into two smaller tubes known as the bronchi. These further divide into smaller and smaller tubes called bronchioles. The bronchioles, at their smallest point of division, bring air to clusters of small, circular air sacks called alveoli. Though alveoli are of a small size, they are the main sites of gas exchange. This is due to the abundance of the alveoli; at average, humans have nearly 500 million alveoli, which combined, form a surface area that is 40 times the surface area of human skin. This provides sufficient surface area for gas exchange to occur. Gas exchange occurs here with the help of a dense network of capillaries surrounding the alveoli. Blood arriving in the alveoli is deoxygenated, produced during respiration, however, the blood already contained in the alveoli is oxygenated. Therefore, the oxygen enters the deoxygenated blood by diffusion. As the oxygen diffuses through the cell membrane and into the blood, each oxygen molecule merges with a haemoglobin molecule -red protein found in red blood cells that helps transport oxygen- to form
Additionally, the walls of the alveoli have a very thin layer, this shortens the time and distance of the process. Furthermore, each alveolus is ventilated and surrounded by capillaries. The capillaries ensure a good blood supply, which is essential due to the blood repeating the process of taking oxygen and delivering carbon dioxide, which ensures that the oxygen continues its flow from the alveoli into the blood. The ventilation on the other hand removes excess carbon dioxide that is not required and restores oxygen levels in the atmosphere of the alveolus. This also helps maximise the concentration gradient between the alveolar air and the blood entering and exiting through the capillaries. Pulmonary ventilation is the act of breathing comprised of two phases; inhalation and exhalation. In inhalation, air from the environment is drawn into the lungs and in exhalation internal air is drawn out of the lungs. The main mechanisms responsible for pulmonary ventilation are atmospheric pressure(Patm), alveolar pressure(Palv) and the intrapleural