How does the lymphatic system physiology work?
Answer
Have you ever noticed swelling in your ankles after a long day at work? Fluid buildup in the ankles can result from disruptions in the body's drainage system. The heart pumps blood throughout the body, and it actually pumps so hard that it squeezes some fluid out of the capillaries. And it is the lymphatic system that gathers all of that fluid and brings it back into venous circulation. How are these lymph vessels able to pump that fluid back into this high-pressure system? The location of reentry is one way the lymph does this. Lymph is quite intelligent about where it tries to enter the high-pressure system; the pressure in the heart at ~120 mmhg. It reenters at the very end of the venous circulation system, where the pressure is ~5 mmhg. The pressure at the vena cavae is much lower than the pressure in the arteries and at the capillaries. What forces the lymph to go forward instead of rushing back? The valves in the lymph vessels keep the fluid going forward. There is a little bit of smooth muscle that lines the lymphatic vessels and valves. As you move around throughout the day, it pushes the fluid forward. In addition to the smooth muscle, there are also skeletal muscles that help in this pumping action.