BIOL 101 Lecture Notes - Lecture 7: External Intercostal Muscles, Bronchiole, Bronchus
Document Summary
The lungs: most mammalian lungs have the same basic structure. Diaphragm which allow the animal to inspire and expire. Inspiration (inhaling) and expiration (exhaling) are the processes by which the lungs take air from the environment, and put waste gases back into the environment. The processes are controlled by the diaphragm and the intercostal muscles (which run between the ribs): during inspiration, the diaphragm contracts and pushes down the digestive organs beneath it. The external intercostal muscles also contract, pushing the ribs up and out. This increases the volume of the lungs, so that they have a lower air pressure than outside the body, causing air to rush in: during expiration, the diaphragm relaxes and is pushed up by the displaced digestive organs. The external intercostal muscles relax, allowing the ribs to fall. This decreases the volume of the ribs which means that they have a higher air pressure than the outside, causing air to rush out.
