The material present in arterioles that is not present in capillaries is
A) fully oxygenated blood.
B) plasma in which carbon dioxide has been added.
C) a lining of endothelial cells.
D) circular smooth muscle cells that can alter the size of the arterioles.
E) white blood cells and platelets.

Question

Quizplus · Accepted Answer

Arterioles have circular smooth muscle cells that can contract or relax, which regulates blood flow and blood pressure. Capillaries lack smooth muscle cells and are only composed of a single layer of endothelial cells. The material present in arterioles and capillaries is oxygenated and deoxygenated blood, respectively. Plasma, white blood cells, platelets, and endothelial cells are present in both arterioles and capillaries.

The Material Present in Arterioles That Is Not Present in Capillaries