BI-2219
The breathing system
Biology · Secondary 4 · Medium · The breathing system
A graph shows how the volume of air in the lungs changes during one complete breath. At one point on the graph, lung volume starts to increase from its lowest value.
What are the diaphragm muscles doing at this point?
What are the diaphragm muscles doing at this point?
- They are relaxing and moving upwards.
- They are contracting and moving downwards.
- They are fixed and not changing length.
- They are alternating rapidly between contraction and relaxation.
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