Because the artery walls are expandable and elastic, blood keeps moving through the body even when the heart is resting between contractions. When the ventricles of the heart contract, the arteries expand to accommodate blood surging from the heart. Between contractions, arteries return to their original size, forcing the blood inside them forward through the body. You can feel a pulse of surging blood wherever arteries are close to the surface of the skin at the neck, wrists, elbows, knees and ankles. Common heart problems involve blockages of the left coronary artery and its branches.
Arterioles control blood flow by dilating and constricting.
Capillaries Capillaries are still smaller vessels that branch out from arterioles near almost every cell in the body. The walls of the capillaries are thin, allowing oxygen from the blood to pass into the cells and waste products to pass from the cells into the blood. Veins and Venules Venules are small vessels that channel blood into veins, which carry blood back to the heart. Veins and venules can accommodate changes in the volume of blood returning to the heart. The walls of veins and venules are thinner and less elastic than arteries and arterioles, so the pressure here is much lower than in the arteries.