How is air breathed in to the lungs so that oxygen reaches the gas exchange surfaces?

The diaphragm contacts and moves down. The intercostal muscles between the ribs contract. This causes the ribcage and the sternum to move up and out. The thorax increases in width from back to front. This results in the pressure within the thorcic cavity decreasing. As there is a lower pressure within the thorax and an increased area within the thoracic cavity the lungs expand. The lungs expanding leads to air from the external environment being brought into the lungs, down a pressure gradient, through the bronchi, broncioles and to the alveoli. It's in the alveoli that gas exchange occurs and oxygen from the air moves into the capillaries.

MS
Answered by Medi S. Biology tutor

3458 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

By what process do proteins leave a cell?


Give 2 features of DNA and explain how each one is important is semi-conservative replication?


What are the innate and adaptive immune systems and how do their roles overlap?


What happens during mitosis?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning