GCSE Biology - Respiratory System
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The Respiratory System
This section is all about how the human body breathes and processes the air taken in by the lungs. This vital bodily function supports life by delivering oxygen to the blood. Unlike some of the other body’s systems, survival without a functional respiratory system is impossible.
The Passage of Air
1. As we breathe in air through our nose or mouth it enters our windpipe, or trachea.
2. The air then splits down two tubes, known as the bronchi, on its way to the lungs.
3. Bronchioles are the final stop before delivery to the alveoli within the lungs. These are very small tubes branching off from the bronchi.
4. Air is delivered to tiny bags inside the lungs called alveoli (alveolus is singular), where the lungs gas exchange function takes place.
Gas Exchange
Each of the alveolus are wrapped in capillaries (tiny blood vessels). Carbon dioxide is transferred from these capillaries and into the alveoli as oxygen passes through the walls of the alveoli into these capillaries to oxygenate the blood.
Red blood cells in the blood contain haemoglobin. The newly-introduced oxygen then bonds with this to form oxyhaemoglobin, which is carried to the various parts of the body that need it.
