Biology / Unit 13 Bio 3187 short lesson, about 20 seconds
Single versus Double Circulation
Captions available
The idea
Single circulation routes blood through the heart once per circuit, as in fish; double circulation routes it through the heart twice, once toward lungs, once toward body.
In practice
A fish's single circuit runs heart to gills to body and back once.
Where people slip
Double circulation repressurizes blood between lung and body circuits; single circulation cannot repressurize between gill and body delivery.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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