Stenosis / narrowing shown experimentally in fluid filled silicone tube. Simple experiment to show how dissolved substances–salts, sugars, metals and minerals, found in the blood and all body fluids assist circulation due to the affect of gravity on density imbalance due to evaporation from the breath, respiratory tract, skin, eyes and hair. My website: www.andrewkfletcher.com My Blog www.inclinedtherapy.com This flow and return system shown experimentally in open-ended soft wall silicon tubing filled with water suspended 2 metres vertically by the centre with both open ends immersed in the water filled bottles, one of which has yellow food colouring added to show a return flow and to show clearly the narrowing caused by the tension applied to the water inside the tube and bottles. Red coloured saline is introduced at the top of the suspended loop of tubing via a T junction and a syringe body to initiate the flow and return circulation, red representing the arterial blood flow in humans and all animals. And the phloem vessels in plants and trees. Yellow representing the venous return flow and the xylem return flow in plants and trees. One of the objectives of the experiment is to show how solutes dense substances alter the fluid tension on the inside walls of the silicon tubing filled with water, which is by no means as pliable as the majority of veins in the human body. At the same time showing how increasing the density of the fluids at the upper part of the experiment …