BRAINCAKEInhalation
Inhalation (inspiration) is an active process: it needs muscle contraction, and therefore energy from ATP.
During inhalation:
• the external intercostal muscles contract and the internal intercostal muscles relax
• this pulls the ribcage upwards and outwards
• the diaphragm contracts and flattens, moving downwards from its relaxed dome shape
• both movements increase the volume of the thoracic cavity
• the pressure inside the thorax and lungs therefore falls below atmospheric pressure
• air flows into the lungs down this pressure gradient, through the nose or mouth, trachea, bronchi and bronchioles to the alveoli
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More in Gas Exchange
- The Human Gas Exchange System
- Gas Exchange in the Alveoli
- Adaptations of the Human Gas Exchange System
- Breathing
- Exhalation
- Protecting the Lungs
- Gas Exchange in Insects
- The Tracheal System
All 23 lessons in Gas Exchange · All Edexcel AS-level Biology topics