# cardiac cycle watch

1. Hey guys, I'm struggling with this question.
In one cardiac cycle, the volume of blood flowing out of the heart along the pulmonaryartery is the same as the volume of blood returning along the pulmonary vein. Explainwhy the volumes are the same although the speed of flow in the artery is greater thanin the vein.
mark scheme answer: larger/wider lumen so greater volume carried

I got the answer from the mark scheme but I still can't understand why the answer includes greater volume where the question is asking why they both got the same volume .. Can anyone explain it for me!
2. (Original post by Hiyam torkamane)
Hey guys, I'm struggling with this question.
In one cardiac cycle, the volume of blood flowing out of the heart along the pulmonaryartery is the same as the volume of blood returning along the pulmonary vein. Explainwhy the volumes are the same although the speed of flow in the artery is greater thanin the vein.
mark scheme answer: larger/wider lumen so greater volume carried

I got the answer from the mark scheme but I still can't understand why the answer includes greater volume where the question is asking why they both got the same volume .. Can anyone explain it for me!

I think they mean the pulmonary artery's lumen is smaller compared to the pulmonary vein's lumen. Since the arterial lumen is smaller, it requires a higher velocity of transport in order to move the same volume of blood as a vein.
3. (Original post by Hiyam torkamane)
Hey guys, I'm struggling with this question.
In one cardiac cycle, the volume of blood flowing out of the heart along the pulmonaryartery is the same as the volume of blood returning along the pulmonary vein. Explainwhy the volumes are the same although the speed of flow in the artery is greater thanin the vein.
mark scheme answer: larger/wider lumen so greater volume carried

I got the answer from the mark scheme but I still can't understand why the answer includes greater volume where the question is asking why they both got the same volume .. Can anyone explain it for me!
I think Zombiejon is about right but I've got a small point to add.
The 'greater volume carried' is probably referring to the idea that the lumen of the artery is narrower and at higher pressure so will be moving at greater velocity so at any given time the vein has more blood in its lumen but it is moving at a slower pace and therefore equaling the outflow of the artery.
4. (Original post by Tenrec)
I think Zombiejon is about right but I've got a small point to add.
The 'greater volume carried' is probably referring to the idea that the lumen of the artery is narrower and at higher pressure so will be moving at greater velocity so at any given time the vein has more blood in its lumen but it is moving at a slower pace and therefore equaling the outflow of the artery.
I got it now .. Thanks a lot for ur help
5. (Original post by zombiejon)

I think they mean the pulmonary artery's lumen is smaller compared to the pulmonary vein's lumen. Since the arterial lumen is smaller, it requires a higher velocity of transport in order to move the same volume of blood as a vein.
Yea I think you right, yesterday I was so confused with it but now I'm fine .. Thanks for ur help

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