Arteries, Veins, Capillaries and Lymph Vessels: Summary

00:00 Well, let me just summarize what we have looked at in this lecture on arteries, veins, capillaries, and lymph vessels. First of all, it’s important you understand the structure of arteries and veins and you know the components of the wall of these vessels. That you understand the importance of elastic arteries, the aorta in its recoil ability to maintain pressure and therefore, flow inside the vessel.

00:35 It’s important to understand the structure of capillaries, the three types of capillaries even though I will emphasize those structures when we look at them in more detail in other organ systems. And finally, I want to let you know that veins and lymphatic vessels have valves.

00:54 These valves stop the retrograde flow of blood, as the blood and lymph pass along these vessels on their way back to the heart. Movement of blood and lymph occurs through these veins and lymph vessels by the action of skeletal muscles, so they’re forcing the blood along and up the veins. So they have valves. So finally, let me show you a party trick, a trick that you can go to a party with and impress your friends about your knowledge of histology. If you look at your hands, the back of your hand, and it’s probably more obvious in my hand and yours, you can see veins running back towards your shoulder along your skin. Well, pick out one of these veins and get two fingers and squeeze on the vein, say near your your knuckles. And close off that vein, so there’s no blood flow through it.

01:54 Then with the finger that’s closest to your shoulder, squeeze that finger along the vein, so you’re squeezing the blood up the vein. Then take that finger away and have a look at the vein, and I can’t see it here at all, because the blood hasn’t flow back due to the presence of valves stopping that retrograde flow of blood. Well now take away that finger, and immediately, the vein fills up with blood. So that’s the illustration of valves in veins. And as I said, that’s a pretty good party trick to go and show off with your friends your knowledge of histology. So thank you very much for listening to this lecture. I hope you’ve enjoyed it.