Biology- HEART & BLOOD

Hi I am studying for my biology exam tomorrow

I've got a question about the heart.

De-oxygenated blood travels to the lungs through the pulmonary artery. Then, the oxygenated blood travels back to the heart through the pulmonary vein.

I understand how the de-oxygenated blood turns into oxygenated blood however how does the oxygenated blood turn back into deoxygenated blood

Please help

Reply 1

Y2_UniMaths

This thread should be in the biology/sciences forum. A moderator should move this thread into the correct forum where hopefully you can find the correct answer :smile:

@Lemur14

Reply 2

S.G.

Tissues require oxygen for respiration. They get the oxygen from the haemoglobin in the blood. Hence the oxygen goes into the tissues. There’s no oxygen in the blood so it’s deoxygenated.

Reply 3

rb16

When the oxygenated blood comes back from the pulmonary vein, it then gets transported around the body by the aorta. When the oxygenated blood travels around the body, the oxygen from blood is used by respiring cells and hence becomes deoxygenated.

Reply 4

peeked

When the blood returns to the heart through the pulmonary vein, it is then pumped out by the left ventricle to the body through the aorta. The blood goes through arteries and capillaries to individual cells. The cells use of up and take the oxygen away from the red blood cells.

A little more detail: when the blood becomes oxygenated in the lungs, the haemoglobin in the red blood cells binds to the oxygen making oxyhaemoglobin. When the blood goes to cells be oxygen is released and the oxyhaemlglobin becomes haemoglobin again.

Reply 5

Lemur14

Volunteer Section Leader

Original post by Y11_Maths

This thread should be in the biology/sciences forum. A moderator should move this thread into the correct forum where hopefully you can find the correct answer :smile:

@Lemur14

Thanks for the tag, it looks like it's been moved there :smile:

Reply 6

Y2_UniMaths

Original post by Lemur14

Thanks for the tag, it looks like it's been moved there :smile:

Happy to help

Reply 7

WhatsOnEmma

I don't know how much detail you need, but basically haemoglobin's (in the red blood cells) affinity for oxygen (how much they want to hold onto oxygen) changes depending on the environment they're in. If there's lots of oxygen about (e.g. when the blood runs next to the lungs), it has a high affinity and so takes on oxygen (so the blood becomes oxygenated). When there's not very much oxygen (e.g. at a respiring muscle), is has a low affinity, which means it drops its oxygen so that the muscle can use it (thus the blood becomes deoxygenated).