why does countercurrent flow yields greater oxygen uptake than concurrent flow? Mention diffusion. Solution Answer: The orientation of medium is perpendicular to the flow of blood in countercurrent flow so that it is leading to higher efficiency of oxygen diffusion to medium flow at differential points whereas in concurrent flow, medium is synchronous and parallel to the flow of blood so that the rate of diffusion from the alveoli to blood capillaries are lower. The both bloodstreams are going to move in a similar or simultaneous pathway. The concurrent flow yields intermediate in transfer efficiency with multivillous oxygen diffusion main found in humans and sheep.