Distinguish between breathing -in and breathing -out
Breathing in, also known as inhalation or inspiration, is the process of taking air or oxygen into the lungs. It involves the diaphragm and intercostal muscles contracting, causing the chest cavity to expand, which creates a negative pressure inside the lungs and draws air in through the nose or mouth.
Breathing out, also known as exhalation or expiration, is the process of expelling air or carbon dioxide from the lungs. It involves the diaphragm and intercostal muscles relaxing, causing the chest cavity to shrink, which creates a positive pressure inside the lungs and pushes air out through the nose or mouth.
In simple terms, breathing in is the act of taking air into the lungs, while breathing out is the act of releasing air from the lungs.