Answer
The walls of arteries have three layers of endothelium, smooth muscle, elastic tissue, and connective tissue. Artery walls must be strong and flexible enough to withstand blood entering them under pressure.
Capillaries are extremely narrow with walls made up of only a thin layer of endothelium formed by a single layer of epithelial cells with a basement membrane.
The walls of veins are made up of the same three layers as the walls of arteries, but there is less smooth muscle in the middle layer and less connective tissue in the outer layer of the wall. Blood leaving the capillaries and entering the veins is under relatively low pressure, so it is not necessary for the walls of veins to be as thick as the walls of the arteries.
Work Step by Step
The walls of arteries have three layers of endothelium, smooth muscle, elastic tissue, and connective tissue. Artery walls must be strong and flexible enough to withstand blood entering them under pressure.
Capillaries are extremely narrow with walls made up of only a thin layer of endothelium formed by a single layer of epithelial cells with a basement membrane.
The walls of veins are made up of the same three layers as the walls of arteries, but there is less smooth muscle in the middle layer and less connective tissue in the outer layer of the wall. Blood leaving the capillaries and entering the veins is under relatively low pressure, so it is not necessary for the walls of veins to be as thick as the walls of the arteries.
