So here we have an example problem that says, the drawing shows a gas and nutrient exchange in a capillary. The missing label indicates the cells of the capillary wall. Fill in the missing label with the correct tissue type and explain how you knew the correct label. And so, notice over here we have the diagram or the drawing showing a gas and nutrient exchange in the capillary. And notice down below what we have is that missing interactive blank that we need to fill in for this problem.

That again is indicating the cells of the capillary wall. And so you can see that we have these arrows pointing from the interactive blank to the cells of the capillary wall. And so our job is to, again, identify the correct tissue type of the cells that are forming that capillary wall and then to fill in that tissue type here in this blank. And so before we do that, let's first orient you on this entire diagram. And so again, it is showing you a capillary here going through the middle of this tissue.

And so, you can see the body cells or the tissue cells surrounding the capillary here. And so, what you'll notice is that the blood within the capillary is coming from the heart. And the blood that comes from the heart is going to contain nutrients and be filled with oxygen. And so notice that the oxygen gas from the blood is going to diffuse into the surrounding tissues because those tissues need the oxygen in order to generate energy to drive their cellular processes. And also notice that food substances, such as the sugar glucose for example, can diffuse from the blood and into the surrounding tissue.

Because again, the surrounding tissues are going to need the nutrients like glucose in order to drive their cellular processes. And then notice that the actively working tissues are going to generate the waste product, carbon dioxide gas, which can diffuse from the tissues and into the blood, where the blood can transport the carbon dioxide gas to our lungs, and we can exhale that carbon dioxide waste product into the surrounding environment. And so what you'll notice is that in this capillary, there's quite a lot of diffusion and exchange occurring between the blood and the surrounding tissues. Again, we have oxygen gas diffusing from the blood into the tissues. We have food substance diffusing from the blood into the tissues.

And we have carbon dioxide gas diffusing from the tissues into the lung. And so because we have so much diffusion occurring between the tissues and the blood, this means that the cells that are forming the capillary wall are going to need to be really thin tissue. And so that is going to allow for rapid diffusion and rapid exchange between the blood and the surrounding tissue. And so recall from our previous lesson videos that the thinnest epithelial tissue is going to be simple squamous epithelial tissue. Because it consists of just one single layer of these squished or flat cells.

And so, that is going to be the correct tissue type that forms the capillary wall. And so that means that the interactive blank here for this problem is going to be simple squamous epithelia. And so that here concludes this example problem, and we'll be able to get some practice applying these concepts moving forward. So, I'll see you all in our next video.