When you inhale, the diaphragm and muscles between your ribs contract, creating a negative pressure - or vacuum – inside your chest cavity. The negative pressure draws the air that you breathe into your lungs.
Physiology of Breathing
By Lori Alma, About.com Guide
Updated: September 22, 2008
About.com Health's Disease and Condition content is reviewed by the Medical Review Board
Explore Cystic Fibrosis
Must Reads
About.com Special Features
8 Ways to Cut Drug Costs
Learn how to save money on medications with these recommendations. More >
Healthy Bodies, Healthy Minds
Keep yourself, and your family, happy and healthy this fall with these tips. More >
Also from About.com:
©2009 About.com, a part of The New York Times Company.
All rights reserved.