O-LevelBiologyTransport in Humans5090/11 · Oct/Nov 2024 · Q161 Mark
When people travel in an aircraft and sit still in their seats for long periods of time, their lower legs may swell up. Which statement explains why this may happen?
AFewer leg muscle contractions occur to push blood along the veins.
BThe rate of the heartbeat is reduced as no exercise is happening.
CThere is little or no arterial blood pressure to force the blood upwards.
DValves in the veins do not fill up with blood to prevent its backflow.
✓ Correct answer
A: Fewer leg muscle contractions occur to push blood along the veins.
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