The arteries are the blood vessels that deliver oxygen-rich blood from the heart to the tissues of the body. Exception- pulmonary artery carries deoxygenated blood from the heart to the lungs. The arteries have thick muscular walls with very narrow lumen.

Veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart, exceptions are the pulmonary veins, which carry oxygenated blood to the heart from the lungs. The veins have thin muscular walls with wide lumen.

Lymph is a straw-coloured transporting fluid of the body. Lymph is a fluid connective tissue derived from tissue fluid. It is picked up by lymph capillaries which join to larger lymph vessels. Lymph is devoid of Red blood cells and blood platelets. It has a few leucocytes. Lymph generating organs are thymus, spleen etc.