Capillaries are one cell thick.
Capillaries
An artery is a vessel with a thick medial layer, consisting of smooth muscle to allow for constriction or dilation in order to control blood flow through the vessel.
Blood capillaries are the thinnest, their walls only a single layer thick in order to reduce the diffusion distance for substances between the blood and tissues.
A capillary is a blood vessel that is one cell thick for the absorption of nutrients and removal of wastes.
veins
arteries
Thicker
an artery
artery
because they carry blood from the heart.
there are only 2 vessels that take blood from the heart. The Pulmonary trunk that bifurcates into the (right and left) pulmonary arteries. and the aorta. the aorta is the largest vessel in the body and certainly would be considered thick walled.
Vein
The tunica interna, is a thin layer only a few cells thick of a vein and artery, made up of connective tissue and elastic fibers. It is sometimes referred to as the intima membrane. It is this layer that gives smoothness to the lining of the vessel, enhancing blood flow.