How does the diaphragm pull air into and out of lungs?

The diaphragm, a dome-shaped muscle located just below the lungs, plays a crucial role in the process of breathing by rhythmically contracting and relaxing. Here's how it works:

Inspiration (Breathing In):

1. Contraction of the Diaphragm: When you inhale, the diaphragm contracts and flattens, moving downwards towards the abdomen. This action increases the volume of the thoracic cavity (the chest cavity).

2. Enlarged Thoracic Cavity: As the diaphragm contracts and the thoracic cavity expands, it creates a lower air pressure within the lungs compared to the atmospheric pressure outside.

3. Air Rushes In: This pressure difference causes air to rush into the lungs through the nose or mouth, filling the expanded lungs with oxygen.

Expiration (Breathing Out):

1. Relaxation of the Diaphragm: After inhalation, the diaphragm relaxes and moves back to its original dome shape. This reduces the volume of the thoracic cavity.

2. Increased Air Pressure: As the thoracic cavity decreases in size, the air pressure inside the lungs becomes higher than the atmospheric pressure outside.

3. Air is Expelled: The increased air pressure forces the air out of the lungs through the nose or mouth, expelling carbon dioxide, a waste product of cellular respiration.

This cycle of diaphragmatic contraction and relaxation continues throughout our lives, facilitating the exchange of oxygen and carbon dioxide between the lungs and the bloodstream. The diaphragm works in coordination with other respiratory muscles, such as the intercostal muscles between the ribs, to ensure efficient breathing.