"To vent one's spleen" now there"s a phrase. In my case I take it to mean "to express one's anger," usually in forceful terms and/or at top volume.
The spleen is, of course, one of those brave little organs nestled in the human midsection (just to the right of the stomach, in this case), performing those thankless tasks we don't notice until something goes wrong and our deductible becomes relevant.
The spleen's job is to act as a sort of filter for the blood, but in the late 16th century it was decided that the spleen was the source of rage and ill-temper. Thus "spleen" has for several centuries been a metaphor for "anger," "resentment" and general crankiness.
Oh you can remove the spleen and still live - education eh......
