Within systemic capillaries, substances such as oxygen, hormones, and nutrients move by ____________ from their relatively ____________ concentration in the blood into the interstitial fluid and then into the tissue cells, where the concentration of these materials is ____________ . very small solutes and fluids may pass via the ____________ , while larger solutes, must pass through the fenestrations in ____________ or gaps in ____________ . endothelial cells may use ____________ to fuse fluid-filled vesicles with the plasma membrane. this type of ____________ can move contents either from the blood to the interstitial fluid or from the interstitial fluid into the blood. solutes such as certain ____________ and fatty acids are transported across the endothelial cells by this method.