Ok. Let's talk about arteries first. Arteries carry blood away from the heart. People (A.K.A. YOU) often mistaken the arteries for always carrying oxygen. BUT THEY DO NOT. The pulmonary artery takes UNOXYGENATED blood to the lungs. HOPEFULLY, you won't make that mistake ever again. Also, arteries are high pressure.
Now let's talk about structure of the blood vessel wall. All blood vessels have 3 layers. From in to out they are the tunica intima, tunica media, and tunica externa.
The tunica intima is made of a layer of endothelial cells.
The tunica media contains the muscle of the blood vessel. Arteries are generally high pressure so they have a larger tunica media. Veins are the opposite. They are low pressure so they don't have a thick tunica media.
The tunica externa is the outmost layer. It is sometimes known as the tunica adventitia. The tunica externa is mainly composed of collagen. It is also supported by external elastic lamina.
Ok. Arteries are high pressure. Veins are low pressure. So how do veins move blood around??? Veins use skeletal muscle movement to help move the blood. They also have valves that prevent the backflow of blood.
I HOPE THIS HELPED YOU. HERE IS A PICTURE OF VEIN AND ARTERY DIFFERENCE:
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