Well, all three of those terms are very close to being the same thing, except for function and location. These are fluids in the body that basically are located between the tissues and cells. Their primary function is to conduct the flow of dissoved substances in the blood, pick up any bacteria or cancerous cells, and deliver those items to their proper destinations for use. In the case of the bacteria and cancerous cells, they are delivered to the lymph nodes to be destroyed. In terms of providing homeostasis, the tissue fluid, plasma, and lymph are like a transportation and sanitation system. Think of homeostasis as the body in business. There are all these different departments that all depend on each other for the survival of the business. These three fluids play an invaluable part in delivering various products within the business. They also play an important part in getting rid of trash, or things that clutter, stack up, and otherwise, get in the way. Without them, homeostasis would be difficult to achieve.