Really tough circulatory system question

[donkeykong1]

Which of the following is most likely the origin of a PULMONARY EMBOLUS that blocks the PULMONARY ARTERY?

a-veins of lower leg
b-left side of heart
c-aorta
d-pulmonary veins

I do not understand the answer explanation at all. Although I had previous knowledge of embolus formation in physiology class.


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ANSWER IS A!-NOT SURE WHY?

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[ilovemcat]

Which of the following is most likely the origin of a PULMONARY EMBOLUS that blocks the PULMONARY ARTERY?

a-veins of lower leg
b-left side of heart
c-aorta
d-pulmonary veins

I do not understand the answer explanation at all. Although I had previous knowledge of embolus formation in physiology class.


---------------------
ANSWER IS A!-NOT SURE WHY?

Was this a passage based question? A Pulmonary Embolism originates from the lower legs and results from poor blood circulation (ie. Plane Flight where you're sitting down for several hours with little to no movement). This isn't common knowledge so something like this wouldn't be included as a discrete.

 

[tartrate]

True, it might not be common knowledge, but regardless, you can reason the answer out.

Which of the following is most likely the origin of a PULMONARY EMBOLUS that blocks the PULMONARY ARTERY?

a-veins of lower leg
b-left side of heart
c-aorta
d-pulmonary veins

So we have a clot in the pulmonary artery...it would make sense to track the path of the clot backwards, since the shorter path would be much likelier than a longer path. Tracing the clot backwards, the earliest point reached of the answer choices is A. Choices B, C, and D all start at roughly the same point, and would have had to travel throughout the entire body in a full circle to get back to the pulmonary artery, which is less likely. Especially if you consider it somehow slipping through tiny systemic capillaries that are in this circuit. If the clot started in the veins, then it has already bypassed the capillary system, and would not have this problem until it reaches the lungs.

 

[LaurenMCAT]

Which of the following is most likely the origin of a PULMONARY EMBOLUS that blocks the PULMONARY ARTERY?

ANSWER IS A!-NOT SURE WHY?

I like tartrate's explanation

The lower leg veins dump into larger and larger structures...the pulmonary arteries are the first narrowing we come to.

 

[ilovemcat]

True, it might not be common knowledge, but regardless, you can reason the answer out.

Which of the following is most likely the origin of a PULMONARY EMBOLUS that blocks the PULMONARY ARTERY?

a-veins of lower leg
b-left side of heart
c-aorta
d-pulmonary veins

So we have a clot in the pulmonary artery...it would make sense to track the path of the clot backwards, since the shorter path would be much likelier than a longer path. Tracing the clot backwards, the earliest point reached of the answer choices is A. Choices B, C, and D all start at roughly the same point, and would have had to travel throughout the entire body in a full circle to get back to the pulmonary artery, which is less likely. Especially if you consider it somehow slipping through tiny systemic capillaries that are in this circuit. If the clot started in the veins, then it has already bypassed the capillary system, and would not have this problem until it reaches the lungs.

Clever

 

[donkeykong1]

thanks tartrate thats a great explanation. Although it was passage based, the answer had to be from common knowledge since it wasn't said straight out in the passage. Needless to say, I kind of got burned on that one passage.

 

[Bacchus]

Pulmonary embolism can be a manifestation of deep vein thrombosis. An embolus is due to some circulating body in the blood causing a clot that isn't at the original location of formation.

 

[agill786]

thanks for the explanation! BTW, what exam was this passage in?

 

[donkeykong1]

thanks for the explanation! BTW, what exam was this passage in?

its a question on one of the kaplan topical exams.

 

[PD187540]

Pulmonary emboli usually originate in the veins of the lower legs. As a Pathology Assistant major, I was taught that in the program. Thank god for a pathology class, huh?

It amazes me how some MCAT questions require almost no work if you've had detailed courses. I don't believe the claim that only your general science pre-reqs are required to do well on the MCAT. Sure, you'll probably do well, but you'll work much harder. I'd say it's in everyone's best interest to take a few specialized courses.

 

[Rabolisk]

It amazes me how some MCAT questions require almost no work if you've had detailed courses. I don't believe the claim that only your general science pre-reqs are required to do well on the MCAT. Sure, you'll probably do well, but you'll work much harder. I'd say it's in everyone's best interest to take a few specialized courses.

​

Those seem to be contradictions, at least a little.

 

[StudyShy]

This is specific knowledge that someone would learn in a pathophysiology class, however by understanding the passage that blood takes through the circulatory system, the answer can be reasoned out. Blood that comes from the lower legs reaches the pulmonary artery before (b) the left side of the heart, (c) aorta, and (d) the pulmonary veins. Therefore, the embolus most likely originates from the the legs since otherwise the embolus would have to have traveled through b, c, d, and the lower legs before it blocks the pulmonary artery which would be unlikely.

 

[Hamiltonian]

This is specific knowledge that someone would learn in a pathophysiology class, however by understanding the passage that blood takes through the circulatory system, the answer can be reasoned out. Blood that comes from the lower legs reaches the pulmonary artery before (b) the left side of the heart, (c) aorta, and (d) the pulmonary veins. Therefore, the embolus most likely originates from the the legs since otherwise the embolus would have to have traveled through b, c, d, and the lower legs before it blocks the pulmonary artery which would be unlikely.

explanation

 

[Wakesc]

I came up with a quick answer by just looking at where the blood was traveling and if it was oxygenated. I'm not sure if it was a correct way but I got the same answer. I reasoned that since the pulmonary artery carries deoxygenated blood to the lungs that where the embolism came from must have just dumped O2. The left side of the heart, aorta and pulmonary veins all carry oxygenated blood so that left A. Not sure if thats perfect reasoning.

 

[pbg4user]

.

 

[shffl]

Like everyone said, this problem is really easy even if you don't know what air embolism is. In accord to most bio passages, you can sort out the answers (most of the time) in a logical fashion.

 

[StudyShy]

" This is specific knowledge that someone would learn in a pathophysiology class,"

I disagree. I covered this in both an EMT and an anatomy class. It seems to be a pretty popular question.

But the average pre-med does not go to EMT school and may not take an anatomy class since these aren't requirements for med school. Of course, you would learn about PE's in medic school.

 

[Bacchus]

But the average pre-med does not go to EMT school and may not take an anatomy class since these aren't requirements for med school. Of course, you would learn about PE's in medic school.

The average premed should know that sitting a long time on an airplane/in a bus/on a train will cause clots though that can travel to your lung. Its the latest health craze besides vitamin D.

 

[Doodl3s]

this is NOT a specific knowledge question. i got this by reasoning about the four chambers of the heart and how it would get there.

Also, to be honest, I think this question was DEFINITELY meant to be a little bit of a trick, because everybody knows how people mess up that pulmonary artery goes TO the lungs with DEoxygenated blood, even though arteries usually go away from things with oxygenated blood... i had to think about which was the pulmonary artery on this question lol

remember, artery AWAY from HEART, and that the left side pumps to body, meaning it must be oxygenated by then.