Q.With the help of neat and labelled diagrams, distinguish between artery and vein.

Artery: thick, muscular and elastic wall (able to withstand high pressure), narrow lumen, carries oxygenated blood away from the heart under high pressure (except the pulmonary artery), no valves (except at the heart'...

Arteries carry blood away from the heart under high pulsatile pressure through thick muscular walls, while veins return blood to the heart under low, steady pressure through thin walls with valves.

To sketch: draw a cross-section of an artery showing a narrow central lumen surrounded by a very thick wall made of three layers — a thin inner endothelium, a thick middle layer of smooth muscle and elastic fibres, and an outer connective-tissue layer — and label it as carrying blood away from the heart. Beside it, draw a cross-section of a vein showing a comparatively wide lumen surrounded by a much thinner wall (thinner muscle and elastic layers), and include a labelled valve (a pair of pocket-like flaps) inside the lumen; label it as carrying blood toward the heart. Functionally and structurally, arteries have thick, muscular, elastic walls that let them withstand and smooth out the high, pulsatile pressure generated by each heartbeat, and (except the pulmonary artery, which carries deoxygenated blood to the lungs) typically carry oxygenated blood away from the heart to the tissues; because pressure inside them is already high, arteries generally lack internal valves. Veins, by contrast, have thin walls with much less muscle and elastic tissue since they carry blood under much lower pressure, and (except the pulmonary veins, which carry oxygenated …