Inhalation Mechanics
Breathing begins when the diaphragm contracts and moves downward while external intercostal muscles lift the rib cage. These actions increase the chest cavity volume, creating negative pressure that draws air into the lungs. Air moves through the airways - nose or mouth, pharynx, larynx, trachea, and bronchi - before reaching tiny air sacs called alveoli. This branching network efficiently distributes air throughout the lungs.
Gas Exchange
In the alveoli, oxygen from inhaled air passes through thin capillary walls into the bloodstream, while carbon dioxide moves from blood into the air spaces. This exchange occurs through diffusion, with gases moving from areas of high concentration to low concentration. The large surface area of approximately 70 square meters created by millions of alveoli enables efficient gas exchange.
Exhalation Process
Exhalation occurs when the diaphragm and intercostal muscles relax, reducing chest cavity volume and creating positive pressure that pushes air out. The elastic properties of lung tissue assist this process by naturally returning to a smaller size. The breathing rate adjusts automatically based on body needs, increasing during exercise or stress and decreasing during rest.Shutdown123