Now, things like water molecules, proteins, gases, nutrients and waste products, hormones and electrolytes, all these things dissolved in their blood plasma, must be able to move across the wall of our capillary. The question is, how does this movement actually take place? Well, recall that our capillary wall is very, very thin. In fact, it's so thin that it only consists of a single endothelial layer. And between the endothelial cells of our capillary wall, we have very tiny junctions, very tiny slits. And these slits and junctions act as pores and allow the movement of the fluid, the blood plasma, along with the molecules dissolved inside the blood plasma across the wall of the capillary.