- Fluids in motion questions
- Volume flow rate and equation of continuity
- Bernoulli's equation derivation part 1
- Bernoulli's equation derivation part 2
- Finding fluid speed exiting hole
- More on finding fluid speed from hole
- Finding flow rate from Bernoulli's equation
- Viscosity and Poiseuille flow
- Turbulence at high velocities and Reynold's number
- Surface Tension and Adhesion
- Venturi effect and Pitot tubes
- Two circulations in the body
- Arteries vs. veins - what's the difference?
- Resistance in a tube
- Putting it all together: Pressure, flow, and resistance
Explore the roles of arteries and veins in the circulatory system. Uncover common misconceptions about oxygenated and deoxygenated blood, and learn the true distinction: arteries carry blood away from the heart, while veins transport blood towards the heart. Delve into the high-pressure nature of arteries and the low-pressure, high-volume characteristics of veins. Created by Rishi Desai.
Want to join the conversation?
- Do lungs also contain systemic arteries/veins, or just pulmonary ones?(57 votes)
- The answer to this can be found in the video "Two Circulations in the Body" at9:30. The lungs receive oxygenated blood from the Bronchial Arteries which are a part of the systemic circulation. Some of the blood drains back through the Bronchial Veins, but some of it joins the deoxygenated blood in the lungs from the Pulmonary Arteries, becomes re-oxygenated, and re-enters the heart through the Pulmonary Veins.(38 votes)
- Based on Bernoulli's equation, higher pressure usually corresponds with lower velocity. If so, why do arteries have both higher pressure and higher velocity than veins?(43 votes)
- Your premise would be true if flow was constant.
Bernoulli's equation states that In the case where Flow is constant, Pressure and Velocity have a negative correlation.
Arteries have a higher flow than veins because of heart.(47 votes)
- How many veins and arteries are there in your body?(35 votes)
- At11:00is a bruise just a vein that has broken and allowed some blood to pool under the skin?(10 votes)
- A bruise also known as a contusion forms because the soft tissues of your body have been bumped. Some people bruise easily whereas others may have tougher skin tissue. When these soft tissue are injured small capillaries(the tiniest blood vessels) under the skin sometimes break red blood cells leak out of these blood vessels.These red blood cells that collect under the skin causing that bluish purplish reddish or blackish mark that you may see(15 votes)
- How many gallons of blood do you have in your body(10 votes)
- An adult has about 5 litres on average, which I think is about a gallon.
EDIT: That's about 1 UK gallon or 1.3 US gallons.(12 votes)
- Another part of the circulatory system is the lymphatic system. How does the lymphatic system interrelate with blood flow?(12 votes)
- The lymphatic system helps retain the plasma fluid found in the matrix of blood vessels as they go through the capillaries. It also filtrates the blood to remove any pathogens, abnormal cells and anything that should not be in the blood vessels.
The lymphatic system also sends out the WBC (white blood cells) into the blood vessels during infection; the circulatory system is a transport system - think of it as a highway.(5 votes)
- At1:15Dr.Desai mentions that the arteries and the veins are trying to deliver blood to the capillaries. What are the capillaries?(7 votes)
- Capillaries are the body's smallest bloods vessels, only one cell thick. This is the place where oxygen and other bloodstream nutrients are exchanged into body tissues. Capillaries also collect fluids and waste materials like carbon dioxide which are carried up into the veins.(10 votes)
- Do the valves in the veins have an equivalent of the chordae tendineae (tendons attached to the walls of the veins) to make sure they stay in the right position?(10 votes)
- The valves in the veins don't need equivalents of the chordae tendineae because the pressure is much lower than in the heart. That way the valves wouldn't flip to the other side, they are strong enough to resist the low pressure of the blood in the veins.(5 votes)
- How do veins generate enough pressure to get the blood all the way back to the heart?(5 votes)
- Ah, that's a very good question that Khan Academy addresses in later videos. To sum it up, there are valves in the veins that prevent blood from going backwards and they move strategically from the movement of the muscles surrounding the vein.
Hope this helped! :)(7 votes)
- How do veins coming from the lower part of body transport blood towards the lungs without any pressure?(3 votes)
- [Instructor] Let's talk a little bit about arteries and veins and the roles they play in the circulatory system. So I want you to pause this video and first think to yourself, Do you have a sense of what arteries and veins are? Well one idea behind arteries and veins are that well, in most of these drawings, arteries are drawn in red, and I even made the artery word here in red. And veins are drawn in blue. And so maybe that represents how much oxygen they have. And so one possible explanation is that arteries carry oxygenated blood, oxygenated, oxygenated blood, while veins carry deoxygenated blood. So blood that has less oxygen now. Now this is actually incorrect. It is, many times, the case that arteries are the ones carrying oxygenated blood and veins are carrying the deoxygenated blood. But as we will see, this is not always the case. And since we're already talking about oxygenated blood and deoxygenated blood and the colors red and blue, it's worth addressing another misconception. Many times it is said that deoxygenated blood looks blue, and the reason why people believe that is if you look at your wrist and you're able to see some of the vessels in there, you will see some blue vessels. And those, or at least they look blue when you're looking from the outside of your skin. And those, indeed, are veins. And so that's where the misconception has come from, that veins, which, in your arm, are carrying deoxygenated blood. That that deoxygenated blood is blue. It turns out that it is not blue. It is just a deeper red. And the reason why the veins look blue is because of the optics of light going through your skin and then seeing the outside of the veins and then reflecting back. That is not the color of the actual blood. So so far I have not given you a clear definition of what arteries versus veins are. A better definition, so let me cross these two out, are that arteries carry blood away from the heart. Away from the heart. And veins carry blood towards the heart. Towards the heart. And I can get a zoomed in image of the heart right here and that will make it a little bit clearer. And you can also see, or we're about to see, why this first definition, or this first distinction between arteries and veins does not always hold. So let's just imagine some blood that is being pumped away from the heart. So right when it gets pumped away from the heart, it'll be right over here. It gets pumped through the aorta, and you can see the aorta branches, so some blood can go up towards your head, and if it didn't, you would pass out and die. And then a lot of the blood goes down towards the rest of your body. And that, indeed, is the most oxygenated blood. And so it'll flow through your body. And these arteries will keep branching and branching into smaller vessels, all the way until they form these very small branches. And it's that place, especially, where they will lose a lot of their oxygen to the fluid and the cells around them. And then the blood is less oxygenated. And then even though deoxygenated blood is not blue, it often gets depicted as blue in a lot of diagrams. So I will do the same. And these vessels start building into your veins. And these really small vessels that really bridge between arteries and veins, where a lot of the gas and nutrient exchange occurs, these are called capillaries. And so after going through the capillaries, the blood will then come back to the heart and now it's coming towards the heart through the veins. It comes into the right atrium, then the right ventricle. Then that gets pumped towards the lungs. And this is the exception to the first incorrect definition of arteries and veins that we looked at. This right over here, is an artery. Even though it's carrying less oxygenated or deoxygenated blood, it's an artery because it's carrying blood away from the heart. But in this case, it's not carrying it to the rest of the body, it is carrying it to the lungs. That is why it is called the pulmonary artery, even though it's carrying less oxygenated blood. So that it goes to the lungs and then, in the lungs, there's more gas exchange that occurs. The blood gets oxygenated and then it comes back to the heart. And so it comes back to the heart in these vessels right over here, and that even though these are carrying highly oxygenated blood, these are considered veins because they're carrying blood towards the heart. So these are pulmonary veins. And then the cycle starts again. The pulmonary veins bring the oxygenated blood into the left atrium and the left ventricle, and then that pumps it to the rest of the body to the aorta, for your systemic circulation. You have your pulmonary circulation, which circulates the blood to, through and from the lungs. And you have your systemic circulation, which takes the blood to and from the rest of the body. So now that we have this main distinction between arteries and veins, what are some other interesting things that we know about it? Well one thing to keep in mind is that since arteries are being pumped directly by the heart towards the rest of the body, they have high pressure. I'll write that in caps. High pressure. And so if you were to have an accident of some type, which you do not want to have, and you were to accidentally cut an artery, because of that high pressure, it would actually spurt blood, a lot more than if you were to cut a vein. And most of the times where you get a cut, you're really just cutting capillaries. Like if you were to prick your finger, it's usually a series of capillaries that get cut, and that's why the blood would come out very very slowly. Now if arteries are high pressure, veins are low pressure. Low, low pressure. And one way to think about it is the arteries, the blood is being pumped directly by the heart. But then once it goes through the capillaries and comes back through the veins, it's kind of sluggishly making its way back to the heart. It's not being directly pumped. And that's why in veins, because you don't have that high pressure to bring everything back to the heart, you have these valves that make sure that for the most part, the blood is going in one direction. I'm going to draw the blood in red in the veins, just so we don't keep going with that misconception, that blood in the veins is blue somehow. Now related to the fact that the blood in the arteries is under higher pressure, in order to transport a fixed volume of blood in a certain amount of time, you need less volume. And so that's why arteries are low volume. And on the other hand, veins are high volume. And to appreciate the difference, the blood volume in arteries are only approximately 15% of the entire blood volume in your body, while the blood volume in veins are closer to 65%, approximately 65%. And if you're wondering where the rest of the blood is, about five percent is in capillaries, five percent is in your heart, and about 10% is in your lungs. So I will leave you there. The big take away: arteries are the vessels that take blood away from the heart. Veins are the vessels that take blood towards the heart.