PATHOLOGY

Detailed explanation-1: -Capillaries have the largest total cross-sectional and surface area. Veins are thin-walled blood vessels that return deoxygenated blood to the heart. Sinusoids are substitutes for capillaries in some organs such as the spleen, liver, red bone marrow, etc.

Detailed explanation-2: -An adult human has been estimated to have some 60, 000 miles (96, 560 km) of capillaries with a total surface area of some 800–1000 m2 (an area greater than three tennis courts). The total volume of this system is roughly 5 liters, the same as the total volume of blood.

Detailed explanation-3: -The nutrients and blood supply reach every part of the cell in the body through the capillaries, so they are intricate and vast. Thus, the capillaries have maximum surface area.