GENERAL HISTOLOGY

Detailed explanation-1: -Arteries have thick walls composed of three distinct layers (tunica) Veins have thin walls but typically have wider lumen (lumen size may vary depending on specific artery or vein) Capillaries are very small and will not be easily detected under the same magnification as arteries and veins.

Detailed explanation-2: -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.

Detailed explanation-3: -The final branches of the circulatory system are the capillaries. Blood capillaries have a very thin lumen for the proper exchange of nutrients and gases. The lumen of the capillaries is very small because the blood flow here is too slow for the maximum exchange process.