So here we have an example problem that asks, which type of capillary would you not expect to find in a tissue where relatively large molecules need to be exchanged between the blood and surrounding tissues, and smaller molecules need to be exchanged rapidly. And we've got these 3 potential answer options down below, which are the 3 types of capillaries that we talked about in our last lesson video. Now, of course, when we look at this problem, it is asking us about the diffusion of relatively large molecules, and it's also asking us about smaller molecules diffusing rapidly. And so, really, in terms of the capillary we would not expect to find in these types of tissues, we would not expect to find the capillary that are the least permeable. And recall from our last lesson video that the capillary that is the least permeable is the continuous capillary. And so we can go ahead and indicate that answer option a, continuous capillaries, is going to be the correct answer to this problem because we would not expect to find them in these areas where large molecules need to diffuse and smaller molecules need to diffuse rapidly. And so, we can go ahead and indicate a is correct because they are the least permeable.

Now looking at answer option b, it says fenestrated capillaries. The fenestrated capillaries have small fenestrations in them, which are these relatively small pores. So they may not allow for the diffusion of relatively large molecules, especially in comparison to the sinusoid capillaries. However, they would allow for the diffusion of smaller molecules to occur more rapidly, and so we would expect to find them more so than, we would expect to find the continuous ones. And so for that reason, we can eliminate answer option b.

And then, of course, answer option c says sinusoid capillaries. These are the most permeable amongst these three types of capillaries. So they would certainly allow for the diffusion of large molecules, and they would allow for smaller molecules to diffuse more rapidly. And so, for sure, we would expect to find them. And, again, we're looking for the answer where we would not expect to find them. And so, answer a, continuous capillaries, is the correct answer to this example. That concludes this example, so I'll see you all in our next video.