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Lecture Notes

As you just learned from the previous video, when blood leaves the heart it travels in the blood vessels, and when blood returns to the heart, it also travels in blood vessels, and we have different names for these blood vessels. Blood that's moving away from the heart is carried in arteries, arterioles and capillaries, and as you can see in these slides here, arteries are the biggest, they get smaller into arterioles, and even smaller into capillaries, where the gasses, the O2, the CO2, can pass through the membranes of those capillaries. On the way back to the heart, blood's carried in venules, which are a little smaller than veins, and then taken back to the heart.