The Gaseous Exchange System

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  • Created by: tiacoles
  • Created on: 15-02-16 21:29

Gas Exchange in Mammals

  • In mammals, the lungs are gas exchange organs.
  • They help to get oxygen into the blood (for respiration) and to get rid of carbon dioxide (made by respiring cells) from the boyd. 

Structure of the gaseous exchange system

  • As you breathe in, air enters the trachea (windpipe) 
  • The trachea splits into two bronchi - one bronchus leading to each lung. 
  • Each bronchus then branches off into smaller tubes called bronchioles.
  • The bronchioles end in small 'air sacs' called alveoli. 
  • This is where gases are exchanged.
  • The ribcage, intercostal muscles and diaphragm all work together to move air in and out. 


  • These form the gas exchange surface.
  • Alveoli are arranged in bunches at the end of the bronchioles. 
  • They are surrounded by a network of capillaries, giving eah alveolus its own blood supply.

Alveoli Structure

  • Each alveolus is made from a single layer of thin, flat cells


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