Question on pulmonary embolism. Watch

Mariah1234
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Hi. I was just wondering if anyone could answer this question for me.

A pulmonary embolism forms in the lower leg. Describe and explain how it can stop oxygen getting to your lungs.

Why is the volume of blood entering the arteries higher than the volume of blood entering the veins?

Thanks.
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Harantony
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I've written a few hints - have a go, and let me know what you think. I can help you some more if you are still struggling, but I want you to reach the answer yourself!

A pulmonary embolism forms in the lower leg. Describe and explain how it can stop oxygen getting to your lungs.

Don't forget that emboli can move around in the veins. Draw a brief map of the circulatory system and note where blood from the legs travels (leg --> heart (which chambers?) --> lungs), to see how easy it is for an embolism to reach the lung vasculature from the leg.

Now, from this, the embolus is in an artery in the lungs. If it's blocking this artery, then what does this mean for oxygen reaching the lungs? Think about the function of blood.

Why is the volume of blood entering the arteries higher than the volume of blood entering the veins?
What does an embolus do? Draw out a diagram of arteries, a capillary bed, and veins. If the embolus gets lodged in the capillary network, then what does this mean for the blood coming out in the veins on the other side?

Hope this helps!
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Mariah1234
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(Original post by Harantony)
I've written a few hints - have a go, and let me know what you think. I can help you some more if you are still struggling, but I want you to reach the answer yourself!

A pulmonary embolism forms in the lower leg. Describe and explain how it can stop oxygen getting to your lungs.

Don't forget that emboli can move around in the veins. Draw a brief map of the circulatory system and note where blood from the legs travels (leg --> heart (which chambers?) --> lungs), to see how easy it is for an embolism to reach the lung vasculature from the leg.

Now, from this, the embolus is in an artery in the lungs. If it's blocking this artery, then what does this mean for oxygen reaching the lungs? Think about the function of blood.

Why is the volume of blood entering the arteries higher than the volume of blood entering the veins?
What does an embolus do? Draw out a diagram of arteries, a capillary bed, and veins. If the embolus gets lodged in the capillary network, then what does this mean for the blood coming out in the veins on the other side?

Hope this helps!
So when the clot breaks off it travels through the bloodstream to the right side of the heart. Veins pump deoxygenated blood back to the right side of the heart. Since the right side of the heart deals with pumping blood to the lungs, the embolism will become stuck in the lungs or the veins directing to the lungs which reduces the oxygen flow to the lungs?
Is that right?
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Harantony
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(Original post by Mariah1234)
So when the clot breaks off it travels through the bloodstream to the right side of the heart. Veins pump deoxygenated blood back to the right side of the heart. Since the right side of the heart deals with pumping blood to the lungs, the embolism will become stuck in the lungs or the veins directing to the lungs which reduces the oxygen flow to the lungs?
Is that right?
Mostly right! You have the right idea.

The embolism won't get stuck in the veins which take blood to the lungs - it will get stuck in the capillaries that contain blood which needs to get oxygenated in the lungs. If the embolus is in the way, then the deoxygenated blood won't be able to get past it to the alveoli where it will be oxygenated.

Also don't forget, it's:
Veins (in systemic circulation) --> right atrium --> right ventricle --> pulmonary arteries --> capillaries --> pulmonary veins. Note how the veins come after the capillary bed where all of this is happening.
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Mariah1234
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Thank you so much! You're a lifesaver!
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Mariah1234
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Would you happen to know what factors affect capillary diameter. I think it's volume of blood and blood pressure but I'm not too sure.
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Harantony
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(Original post by Mariah1234)
Thank you so much! You're a lifesaver!
No problem!


(Original post by Mariah1234)
Would you happen to know what factors affect capillary diameter. I think it's volume of blood and blood pressure but I'm not too sure.
Those 2 do have an effect indirectly on other blood vessels via reflexes - blood volume affects blood pressure, so arterioles dilate to lower blood pressure if it's too high. Lots of things can affect diameter of vessels - for example, in the brain, if metabolic demand is higher than oxygen being delivered to it, blood vessels will dilate. This is a local response.

You'll find that things like standing up quickly will also cause vasoconstriction in some areas and vasodilation in others: this is more of a wide-spread effect than just local factors, and this is due to blood pressure falling again.

Capillaries don't really change their diameter by themselves as they're only one cell layer thick: cells pretty much have to go in single file down a capillary.

Hope this helps!
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