MICROANATOMY

Detailed explanation-1: -Your inferior vena cava, your body’s largest vein, carries oxygen-depleted blood back to your heart from the lower part of your body (below your diaphragm).

Detailed explanation-2: -The smallest vessels being the capillaries begin to fuse to give rise to venules and veins. The size of the veins closest to the heart is the largest among all the vessels.

Detailed explanation-3: -Veins are generally larger in diameter, carry more blood volume and have thinner walls in proportion to their lumen. Arteries are smaller, have thicker walls in proportion to their lumen and carry blood under higher pressure than veins.

Detailed explanation-4: -In other words, in comparison to arteries, venules and veins withstand a much lower pressure from the blood that flows through them. Their walls are considerably thinner and their lumens are correspondingly larger in diameter, allowing more blood to flow with less vessel resistance.