Breathing

Breathing is moving air in and out of the lungs. The air going in and out is called breath. If a person cannot breathe, they will die.

Breathing helps people do two very important things:^[1][2]

1. Get oxygen into the body. Every part of the body needs oxygen to survive. The only way humans can get oxygen is to breathe it in.
2. Get carbon dioxide (CO₂) out of the body. When the body makes energy, carbon dioxide gets left over. The body needs to get rid of extra carbon dioxide, because too much of it is poisonous. The only way humans can get rid of carbon dioxide is to breathe it out.

When a person breathes in, they bring air into their lungs. Air has oxygen in it. The oxygen goes from the lungs into the person's bloodstream. When oxygen goes into the bloodstream, extra carbon dioxide comes out and goes into the lungs. This is called gas exchange: basically, oxygen and carbon dioxide are changing places. Oxygen is now in the bloodstream, which can carry that oxygen around to every part of the body. Also, carbon dioxide is now in the lungs, where it can be breathed out.^[2]

Adults breathe about 18 times a minute, which is more than 25,000 times a day. Children breathe even faster.^[1]

1. ↑ ^{1.0 1.1} Barrett, Kim E.; Barman, Susan M.; et al. (April 26, 2012). Ganong's Review of Medical Physiology (24th ed.). McGraw-Hill Education. ISBN 978-0071780032.{{cite book}}: CS1 maint: multiple names: authors list (link)
2. ↑ ^{2.0 2.1} Lechtzin, MD, MHS, Noah. "Exchanging Oxygen and Carbon Dioxide". Merck Manual. Merck & Co., Inc. Retrieved January 29, 2016.{{cite web}}: CS1 maint: multiple names: authors list (link)