Start direction
What defines an exchange question before a mechanism is chosen?
Check
The substance, spaces, gradient and conditions of the question.
FOUR ORIGINAL PROMPTS
Map the
exchange route.
Recall first, then verify detailed physiology in an approved source.
Find the bottleneck
What connected steps should be considered in gas exchange?
Check
Ventilation, the exchange barrier, perfusion and transport.
Read the model
Why state assumptions?
Check
They show where a simplified mechanism applies and where a source-backed exception matters.
Use context
Why might time or activity change the explanation?
Check
They can alter demand, movement and the system’s response.