Body fluids generally refer to the liquid substances in the body. body fluids include two major parts: intracellular fluid and extracellular fluid, with intracellular fluid accounting for 2/3 of all body fluids and extracellular fluid accounting for 1/3 of all body fluids. body fluids commonly include human plasma, blood, tissue fluid, fluid in the pleural cavity, fluid in the abdominal cavity, cerebrospinal fluid, semen, and vaginal fluid are all within the scope of body fluids. In addition, exolymphatic fluid also belongs to body fluid, so body fluid is a very large range. In addition, body fluids are circulating and connected to each other. For example, human lymphatic fluid is the blood exuding into the intertissues after which part of the tissue fluid then seeps into the lymphatic system through capillary lymphatic vessels and finally flows back into the blood circulation system, so the body fluids of the human body consist of multiple parts.