In a very basic sense of the term circulatory system, the human body utilises three main types of circulatory body systems. These include:
1. The Arterial Circulatory System, which involves oxygenated blood that leaves the heart for the capilaries and individual cells that require oxygen;
2. The Venous Circulatory System, which involves de-oxygenated blood that leaves cells and travels back to the heart for re-oxygenation; and
3. The Lympathic Circulatory System, which is involved in draining excess fluid.
The Lymphatic System serves the following three purposes:
1. To drain excess fluid from various tissue spaces (normally intersitial fluid);
2. To transport dietary lipids and lipid soluable vitamins from the gastrointestinal tract (GIT) through to circulating blood. Lipid soluable vitamins, include: A, D, E and K;
3. Facilitating immune response. The lymphatic system is responsible for creating and storing lymphocytes and macrophages, which assist immune response by identifying and attacking foreign cells, such as bacteria, microbes, toxins, and cancerous cells. The lymphatic system is also responsible for releasing T-cells (also known as Thymus Cells) and B-cells (also known as Bursal Cells), which play an important part in immune response. T-cells , when released destroy invading cells, where as B-cells produce antibodies, which as specifically designed to target and fight specific bacteria, virus or foreign substances.