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A level biology help

"As levels of activity increase, the heart can respond to the changing demand for oxygen. During the cardiac cycle there are pressure changes in the chambers of the heart. Explain how pressure differences in the heart ensure efficient pumping of the blood into the arteries."

this is a 3 marker question i had to answer but i couldn't get it right. i haven't got a mark scheme for this question so i'm unsure on how its supposed to be answered. there needs to be reference made to the cardiac cycle in the answer.
Hi,

There are a few possible points/notes you can make to get your 3 marks.

If you are able to draw a rough sketch of the pressure changes in the aorta and left ventricle during the whole of one cardiac cycle, it would defo make the concepts easier to describe/explain.

1. Mention that systole (pronounced "sis - tul - i" NOT "sis - toul") is the when the ventricles are actively contracting.
2. As the ventricles contract the pressure inside the ventricles increases.
3. When the pressure in the left ventricle exceeds the pressure in the aorta, the aortic (left semi-lunar) valve opens, and:
4. Blood is forced out from the left ventricle into the aorta.
5. (the Q mentions "as levels of activity increase" SO, I would predict there is one mark for saying that during exercise or other physical activity, the force of contraction of the heart increases = positive inotropic effect (and the heart rate increases= positive chronotropic effect = google it!), so more blood is pumped into the aorta (and into the pulmonary artery on the right side) TO HELP SUPPLY MORE OXYGEN to these active muscles AND to pick up more O2 in the lungs, respectively.

Hope this helps - I will try to upload the diagram I mention soon.

M (specialist biology tutor)

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