The three types of blood vessels are:
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Arteries
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Veins
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Capillaries
Arteries:
The arteries carry oxygenated blood except the pulmonary artery, which carries deoxygenated blood to the lungs. Arteries carry oxygenated blood away from the heart. It supply nutrient to different organs of the body. Hence, there is lot of pressure in arteries and blood moves quickly then other vessels.
The arteries have thick muscular walls and elastic walls. The lumen is small in arteries so as to have protection from the high blood pressure.
The examples are pulmonary artery (lungs), coronary artery (heart), iliac artery (leg), Brachial artery (arm), radial artery (wrist, hand), etc.
Veins:
The veins carry deoxygenated blood except he pulmonary vein which carry oxygenated blood from the lungs to the heart. The pressure in the veins is quite low compared to arteries, and blood also moves in slow speed compared to arteries. They carry deoxygenated blood towards the heart except the pulmonary veins.
The veins have thin muscular wall and the even thin elastic walls. The lumen of the veins is large as there is no need of high blood pressure.
The examples of veins are Jugular vein (head), iliac vein (leg), hepatic portal vein (gut), femoral vein (thigh), ulnar vein (hand), etc.
Capillaries:
The capillaries serve as the connecting link between the arteries and the veins. They run through every tissue of the body. They carry oxygen to the tissues of the body. The blood pressure is lost when it enters capillaries. The blood becomes deoxygenated when it enters the capillaries.
The capillaries are very thin, so as to diffuse oxygen quickly in the tissue and take away the carbon dioxide from the tissue.
