Entry of lymph into the lymphatic capillaries is promoted by which of the following? a. one-way minivalves formed by overlapping endothelial cells, b. the respiratory pump, c. the skeletal muscle pump, d. greater fluid pressure in the interstitial space.

Video transcript

Hi everyone. Our next question asks, which of the following is the structure of a single layer of overlapping endothelial cells that allows lymph to flow into lymphatic vessels but not out choice. A lymph nodes. B lymph capillaries, C lymphatic trunks or D subclavian veins. Well, if we couldn't recall right off the top of our head, if we're talking about a single layer of cells, our best bet is indeed our answer choice. B the lymph capillaries capillaries are tiny little structures with just a single layer of cells. And this does indeed a make an arrangement so that lymph can flow into lymphatic vessels but not out because since these cells overlap, when the pressure of the intra fluid in the tissues is greater than the pressure in running through the capillaries, those overlapping cells are forced open a little bit, creating gaps that allow fluid and particles into the capillaries. When the pressure is greater inside the capillaries than out in the tissues. Imagine like a swinging door that swings open when the pressure is greater on the tissues. When it's greater on the capillaries that swinging doors for shut the cells adhere more tightly to each other and nothing can flow out. So the capillaries are that structure a single layer, overlapping cells that regulate the flow of that lymphatic fluid from the tissues into the limp capillaries. When we look at choice, a lymph nodes, those are not the structure of a single layer of cells. Those are small bean like structures that filter lymphatic fluids and contain immune cells. That's why that's not correct. And then so I see lymphatic trucks, excuse me, lymphatic trunks. And these are part of the lymphatic vessel system. But as you can tell by that name trunks, these are the large lymphatic vessels that smaller vessels drain into. So they're formed at the convergence of multiple lymphatic vessels. So they do not have this structure of just a single layer of cells. So that's why choice c isn't correct. And finally, subclavian veins, these are blood vessels, but they are a part of this lymphatic system in a sense because lymphatic fluid that has drained into collecting ducts goes into the subclavian veins which then joined to make the superior Nike, but they definitely don't have a structure of just a single layer of cells. So are not our correct answer. So again, the structure of a single layer of overlapping endothelial cells allowing lymph to flow into lymphatic vessels but not out choice B limp capillaries. See you in the next video