So here we have an example problem that wants us to choose one of the 4 potential answer options down below that best fills in the blanks in the sentence. And so notice that the sentence says, if the body requires blood in skeletal muscles, blank in the digestive system will blink. And so recall from our last lesson video that if one area of the body needs blood more than another area of the body, then the body is able to redirect the blood flow toward the area of the body that needs the blood more. And so I've gone ahead and sketched out something that I think may be helpful to visualize this scenario. Notice that over here on the left, what we have is tissue number 1, and over here on the right, what we have is tissue number 2. Tissue number 1 is in a scenario where it needs more blood, whereas tissue number 2 is in the scenario where it does not really need more blood. Because tissue number 1 needs more blood, the arteries that are going toward tissue number 1 are going to dilate, and dilate means they will enlarge in order to allow more blood flow to rush towards this tissue. Whereas in tissue number 2, because it does not need more blood, it is going to have its arteries that are feeding blood to it, constrict, and that means that it will narrow down to reduce blood flow going to tissue number 2, and that will ultimately help to redirect the blood flow to tissue number 1, who needs that blood even more.
When we reread this problem here, what you'll notice is that it says that if the body requires blood in the skeletal muscles, what that's saying is that tissue number 1 must be the skeletal muscles. So we can label it as so, and, it needs more blood. So its arteries will dilate. But tissue number 2, in this case, must be the digestive system, so we can go ahead and label it as so. What you'll notice is that it does not need more blood. And so, what we can see is that its arteries are going to constrict. And so what we would expect to see is something here that says something about arteries or arterioles or something of that nature, and then over here, we would expect that it's going to constrict.
Taking a look at the answer options, notice option a says, veins in the digestive system will constrict. But veins are taking blood away from the digestive system, and veins are not going to have the ability to vasoconstrict nearly as much as arteries. So for that reason, we can eliminate answer option a. Option b says, capillaries in the digestive system will dilate, but we know that capillaries lack smooth muscle, and so they lack the ability to vasoconstrict and vasodilate. So we're going to eliminate answer option b for that reason. And so now we're between either answer option C or answer option D. Notice they both are referring to terminal arterioles in the digestive system, but option c says that they will dilate, whereas option d says they will constrict. Again, in the digestive system, as we just discussed, the arteries, or terminal arterioles in this case, are going to constrict. And so that means that answer option d, terminal arterioles in the digestive system will constrict, is going to be the correct answer to this example problem. And answer option c is not going to be correct. And so, that concludes this example problem. Option d is correct, and I'll see you all in our next video.