The spleen, liver, pancreas, and kidney are part of which body systems?

The kidneys are part of the urinary system. The Urinary System or Urinary System is responsible for the production and elimination of urine, has the function of filtering the "impurities" of the blood circulating in the body.  In short, the kidneys filter out impurities and eliminate them in the urine. The liver and pancreas are part of the digestive system. The digestive system is responsible for digesting food, breaking it into smaller parts so that the necessary substances (nutrients) are absorbed by the body. The digestive system is formed by the digestive tract, which comprises the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus, as well as the accessory organs, which are the teeth, tongue, the salivary glands, the liver, the gallbladder and the pancreas. The spleen is part of the lymphatic system. The lymphatic system is the main defense system of the body. It consists of lymph nodes (lymph nodes), ie a complex network of vessels, responsible for transporting lymph from tissues to the circulatory system.