PATHOLOGY

Detailed explanation-1: -Each type of vessel has a lumen-a hollow passageway through which blood flows. Arteries have smaller lumens than veins, a characteristic that helps to maintain the pressure of blood moving through the system.

Detailed explanation-2: -In biology, a lumen (plural lumina) is the inside space of a tubular structure, such as an artery or intestine. It comes from Latin lumen ‘an opening’.

Detailed explanation-3: -Vessels that, when relaxed, measure <400 m in lumen diameter act as the major site of vascular resistance and include a network of small arteries (lumen ≈100 to 400 m) and arterioles (<100 m).