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Question Video: Understanding the Directional Flow of Veins and Arteries Biology

Fill in the blanks: The blood vessels that carry blood away from the heart are the _; the blood vessels that carry blood toward and into the heart are the _.

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Video Transcript

Fill in the blanks. The blood vessels that carry blood away from the heart are the blank; the blood vessels that carry blood toward and into the heart are the blank. (A) Arteries, veins or (B) veins, arteries.

Here is a simplified diagram of the human heart. Whenever we look at a diagram such as this, we need to remember that the left side of the image represents the right side of the heart and the right side of the image represents the left side of the heart. This is because we always draw it as if we are looking at the heart of person standing facing us. You may recall that the right side of the heart receives deoxygenated blood and pumps it out to the lungs so that it can pick up oxygen. By contrast, the left side of the heart receives oxygenated blood returning from the lungs and pumps it all around the rest of the body so the oxygen can be delivered to the tissues for cellular respiration.

Now, let’s have a look at the two types of blood vessel that are responsible for carrying blood toward and away from the heart. The first is a vein. Veins have a thin wall and a large lumen, which is just the scientific name for the cylindrical space in the middle of vessels that the blood flows through. Veins also have valves which open and close to prevent blood from flowing backwards. These features make veins well adapted for carrying blood that is returning to the heart from the tissues and is therefore under low pressure.

The second type of blood vessel is an artery. Arteries have a thick, elastic wall and a narrow lumen. These adaptations mean that arteries are able to withstand and maintain the high pressure that blood is under as it flows away from the heart. Blood leaving the heart must be under high pressure to ensure it reaches the lungs and all the other tissues of the body which need oxygen for cellular respiration. We can now label the two blood vessels at the top of the heart diagram as arteries and the remaining ones as veins.

A good way to remember that arteries carry blood away from the heart is that the words “artery” and “away” both start with the letter “a.” We can also remember that veins carry blood into the heart because within the word “vein” is the word “in.” We have therefore determined that the correct answer to the question is (A). The blood vessels that carry blood away from the heart are the arteries; the blood vessels that carry blood toward and into the heart are the veins.

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