The spleen is located under the left side of the diaphragm and near the stomach, pancreas, liver and the heart. The inferior vena cava and the hepatic artery, coming from the heart, are located to the right of the spleen. The organ is protected by the rib cage.
The diaphragm is the organ that allows humans to breathe. It is an automatic function controlled by the brain. The stomach collects food before it goes to the small intestine. The pancreas, sitting behind the stomach and adjacent to the spleen, helps control blood sugar.
The liver filters blood coming from the digestive tract, removing chemicals and metabolizing any drugs taken before the blood goes to the rest of the body. The heart is the engine that pumps the blood.
The spleen works with the liver and is responsible for purifying blood and storing blood cells. It also helps the immune system fight diseases and infections. The spleen has two sections, a white pulp that produces immune cells and some blood cells, and a red pulp that removes old or dead blood cells.
The spleen usually can't be felt by palpation unless it is diseased and swollen. Once it reaches that point, the spleen usually is removed and the liver takes over its blood cleaning and immune system activities. People can live without a spleen, but not without a liver.