Edexcel IGCSE Biology · Spec 2.46-2.48
Breathing and the Lungs
The breathing system, how we breathe in and out, and how the alveoli are adapted for gas exchange.
Biology revision video
Breathing and the Lungs
Prefer to watch on YouTube? Open this video on YouTube.
Spec 2.46-2.48
What you need to know
- Name the parts of the breathing system
- Describe how we breathe in and out
- Explain how alveoli are adapted for gas exchange
Active recall
Quick check
Answer each question before opening the answer.
Describe what happens during inhalation.
The diaphragm contracts and flattens, external intercostal muscles contract pulling ribs up and out, chest volume increases and pressure falls, so air moves in.
Give three adaptations of alveoli for gas exchange.
Any three of: large surface area, thin (one-cell) walls, moist surface, good blood supply maintaining a steep concentration gradient.
Biology video companion
Keep your notes and exam practice together
The free Biology workbook follows every video in specification order.