NEET PG DENTAL EXAM

Detailed explanation-1: -Veins and venules have much thinner, less muscular walls than arteries and arterioles, largely because the pressure in veins and venules is much lower.

Detailed explanation-2: -Capillaries are thin-walled vessels composed of a single endothelial layer. Because of the thin walls of the capillary, the exchange of nutrients and metabolites occurs primarily via diffusion. The arteriolar lumen regulates the flow of blood through the capillaries.

Detailed explanation-3: -Veins carry unoxygenated blood towards the heart, away from tissues at low pressure so the lumen is large. Blood moves more slower and often against gravity so valves and a larger lumen ensure it is still transported efficiently. Capillaries have the smallest lumen but relative to their size the lumen is quite large.

Detailed explanation-4: -The tunica adventitia is the outermost layer and consists of connective tissue that anchors the vessel to surrounding tissues. Arteries typically have a thicker tunica media and a narrow lumen, compared to veins which have thinner tunica media, and a wide lumen.