You asked:
What does the spleen do? — Matt, Melbourne, Australia

Marshall Brain Answered:
The spleen gets no respect. Most people know that the heart pumps blood and the stomach digests food, but what does the spleen do? And why is it always rupturing? The only time we hear about the spleen seems to be when someone “ruptures their spleen”.

The spleen is part of the immune system. It filters the lymph to pull out foreign cells and cells tagged by the immune system for removal. It also sorts old red blood cells out of circulation.

Spleens, being full of the liquid they are filtering, can get enlarged. Once enlarged, spleens are prone to rupture mostly through trauma like a car accident. When they rupture, spleens bleed profusely. So a ruptured spleen is either removed or repaired. People who lose their spleens usually get sick more often than people with healthy spleens, because a part of their immune system is missing.

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