What happens to your chest volume when you breathe out?

When you breathe out, your chest volume decreases. This happens in a series of steps:

1. The diaphragm, a dome-shaped muscle at the bottom of your chest, relaxes and moves upward into the chest cavity.

2. The intercostal muscles between your ribs also relax, causing your rib cage to contract inward and downward.

3. These movements increase the pressure inside your chest cavity relative to the outside air.

4. Because air moves from areas of high pressure to areas of low pressure, this forces air out of your lungs and out of your body.

5. As a result, the volume of your chest and lungs decreases, making your chest appear smaller.

When you breathe out, also known as exhalation, the volume of your chest decreases. Here's a step-by-step explanation:

1. The process begins when you decide to exhale and your brain sends a signal to the muscles involved in breathing.

2. The diaphragm, which is the primary muscle used for breathing, relaxes and moves upwards into the chest cavity.

3. The intercostal muscles, which are the muscles between your ribs, also relax, causing your rib cage to contract inward and downward.

4. These movements decrease the space in your chest cavity, which in turn decreases the volume of your chest.

5. As the volume of your chest decreases, the pressure inside your chest increases.

6. This increased pressure pushes air out of your lungs, and you exhale.

7. Once the air is expelled, the process can start again with inhalation, where the chest volume increases as the diaphragm contracts and moves downward, and the intercostal muscles contract, moving the rib cage outward and upward.