The relationship of the lymphatic vessels to the blood vessels

The lymph begins as a tissue fluid derived from blood capillaries, then enters the lymph capillaries and then travels through the lymphatic vessels and nodes. It then enters the blood steam through veins at the root of the neck. 

Blood vessels carry nutrients, water, oxygen and waste products to and from your body cells. There are three primary types of blood vessels: arteries, capillaries, and veins. The functions include transporting blood away from the heart (arteries), transporting blood toward the heart (veins), and capillaries, which connect the arteries to the veins.

The lymphatic vessels pick up and return excess tissue fluid to the blood vascular system.

The vessels carry lymph from peripheral tissues to the venous system. The lymphatic system transports lymphocytes, is involved in the removal of foreign matter & cell debris by phagocytes & is part of the body's immune system. It also transports fats from the small intestine to the blood.

Components of the lymphatic system:

Lymphatic vessels, Lymph nodes, Spleen, Thymus, Tonsils, Peyer’s Patches, Appendix

Work cited: http://www.lymphedemablog.com/wp-content/uploads/2011/09/Lymphatics.gif