Gut: The Inside Story of Our Body’s Most Underrated Organ

by Giulia Enders

Lymphatic vessels are so slight because they do not have muscular walls like our blood vessels. Often, they work just by using gravity. That explains why we sometimes wake up in the morning with swollen eyes. Gravity is not very much help when you are lying down. The tiny lymphatic vessels in our face are nicely open, but it is only when we get up and gravity kicks in that the fluid transported there during the night by our blood vessels can flow back down. (The reason our lower legs do not fill up with fluid after a long day on our feet is that our leg muscles squeeze the lymphatic vessels every time we take a step and that squeezes the fluid—known as lymph in medical circles—upwards.) The lymphatic system is seen as an under-appreciated weakling everywhere in the body except in the small intestine.