How do we breathe?
Breathing consists of two phases: breathing in (inhalation) and breathing out (exhalation). Breathing involves the movement of air into and out of the chest, and is also called ventilation. The term respiration relates to the exchange of gases in the lungs that happens when you breathe.
The respiratory system works so that you breathe in and out comfortably at rest where the least effort is required to move air – and you’re probably not conscious of your breathing. When you exercise, you need to move more air. To do this you can take bigger breaths or breathe more quickly – usually both.
What happens when we breathe in and out?
Although breathing is usually automatic, you can control it if you want to, such as when you talk or sing, for example.
Have you ever thought about what is happening in your body when you breathe in and out? Once you focus on your breathing, you might be able to feel the following things happening.
When we breathe in:
- The diaphragm and the muscles just under our ribcage contract. The diaphragm moves downward, increasing the volume of the chest cavity, and the muscles pull the ribs up and outward, expanding the rib cage and further increasing chest volume
- This increase of volume in the chest lowers the air pressure in the lungs compared to air outside the body
- As air always flows from a region of high pressure to an area of lower pressure, it then enters the body’s airway (nostrils, throat, larynx and trachea) and then into the lungs
When we breathe out:
- The diaphragm and muscles under the ribcage relax, restoring the chest cavity to its original (smaller) volume
- This pushes air out from the lungs into the atmosphere as exhaled breath
How does your body control breathing?
Our body needs oxygen to function. Your brain continuously receives signals from your body telling it how much oxygen is in your blood. When you start vigorous exercise, your brain signals to the muscles involved in breathing to speed up your breathing rate so your muscles get enough oxygen. Through working harder, your lungs also prevent undue build-up of carbon dioxide in your bloodstream, taking it out of your body in your breath.
This control is automatic, involuntary and continuous, so you don’t have to think about it.
What function does the nose have in breathing?
Your nose helps trap and filter impurities in the air you inhale before it reaches the lungs.
Let’s look at what those impurities are in more detail: