How and why air moves into out of lungs when you inhale exhale?
Air moves into and out of the lungs during inhalation and exhalation due to changes in pressure within the thoracic cavity. The primary muscles involved in this process are the diaphragm and the intercostal muscles. Here's a detailed explanation of how and why air moves during these processes:
Inhalation (Breathing in):
1. Diaphragm Contraction: The diaphragm, a dome-shaped muscle located at the base of the lungs, contracts. This contraction increases the vertical dimension of the thoracic cavity.
2. Expansion of Thoracic Cavity: As the diaphragm contracts, it pulls the lungs downward, causing the chest cavity to expand. This expansion creates a lower pressure within the lungs compared to the atmospheric pressure outside.
3. Air Flow: The lower pressure in the lungs creates a pressure gradient, causing air to flow into the lungs through the nose or mouth. The air travels through the trachea, bronchi, and bronchioles into the alveoli, the tiny air sacs where gas exchange takes place.
Exhalation (Breathing out):
1. Diaphragm Relaxation: The diaphragm relaxes, moving upward and reducing the vertical dimension of the thoracic cavity. The intercostal muscles between the ribs also relax.
2. Elastic Recoil of Lungs: The lungs have a natural elasticity due to the presence of elastic fibers. As the diaphragm and intercostal muscles relax, the elastic recoil of the lungs causes them to recoil and decrease in volume.
3. Air Flow: The decrease in lung volume increases the pressure within the lungs, creating a pressure gradient. This gradient causes air to flow out of the lungs through the airways and out of the body via the nose or mouth.
So, the movement of air into and out of the lungs is driven by changes in pressure within the thoracic cavity. The contraction and relaxation of the diaphragm and intercostal muscles alter the volume of the thoracic cavity, creating pressure differences that cause air to flow in during inhalation and out during exhalation.