Study guide blood vessels lec 07. What are the 3 divisions of the blood vascular system and explain. Compare an artery and a vein in terms of their function and specializations. Describe the histology of the endothelium and also its properties. Compare the internal elastic membrane b/w an artery and vein. What does the tm consist of and describe the ecm btw an artery and vein. Note: if you want to differentiate a large artery from a smaller artery, then you want to see how many layers of smooth muscle are there in the tunica media. Large vein: 5-15 layers of sm (vena cava) Note: blood travels from the arterioles into capillaries and then into the venous system. Note: sphincter is smooth muscle; sm of the areteriole will control the flow of blood into the capillary bed. Compare and contrast the 3 types of capillaries. Note: bbb = perivascular feet of astrocytes, basement membrane, endothelial cells.