Here are three things you should know about your spleen: it filters blood and holds a reserve of red blood cells in case of emergency, it is an important part of your immune system, and it is connected directly to the brain through the vagus nerve.
Think of this organ—which is in the upper part of the abdomen, to the left of the stomach and protected by the rib cage—as fist-shaped and about four inches long. It is the largest lymph node in the body.
As blood passes through it, old red blood cells are removed. Their hemoglobin is broken down into amino acids and their heme—a molecule containing iron—is metabolized into bilirubin, removed by the liver and excreted in bile, feces and urine. Iron is returned to the bone marrow, where new red cells are made. The spleen holds a reserve of red blood cells, used in pregnancy and in case of serious bleeding. It also stores platelets, used for blood clotting, and white blood cells.
As blood flows through it, the spleen detects infectious particles, such as bacteria and viruses. Along with your other lymph nodes, it puts out lymphocytes—a type of white blood cell that can produce antibodies to neutralize bacteria and viruses—and other substances toxic to the invading cells. The spleen stores half the body’s supply of monocytes, another kind of white blood cell that moves to injured tissue and promotes healing.
The spleen also serves as an important connection between the brain and the immune system. In 2008, for the first time, fibers of the vagus nerve were found in the spleen. The vagus nerve supplies parasympathetic fibers to most organs in the body and influences heart rate, digestive processes, sweating, speech and other functions. In contrast to sympathetic nerve fibers—think fight or flight, excitement and anger—the parasympathetic branch of the nervous system is associated with relaxation, a slower heart rate, lower blood pressure and feelings of calm. Research is ongoing on vagus nerve stimulation in people with severe seizures, depression and severe pain. Activation of the parasympathetic nervous system is also associated with decreased inflammation in the body. In situations of severe septic infections, stimulation of the vagus nerve gives increased survival in laboratory animals.
Long, slow breathing, preferably through the nose, is a simple way you can derive the benefits of vagus nerve stimulation. Most meditation methods use this kind of breathing. Establishing a daily practice of relaxation can lower blood pressure, help digestive disorders, decrease anxiety and possibly improve your immune system. Research in this is ongoing.
Take care of your spleen. Most trauma occurs in serious auto accidents; sometimes the spleen has to be removed as a result. You can live without the organ, but not as well. So drive cautiously and defensively, banish road rage, wear your seat belt and forget texting while you drive. A healthy, intact spleen is worth the effort.