Types of Blood Vessels - Online Tutor, Practice Problems & Exam Prep

The circulatory system comprises five major blood vessels: arteries, arterioles, capillaries, venules, and veins. Arteries transport oxygenated blood away from the heart, branching into smaller arterioles that lead to capillaries, where gas and nutrient exchange occurs. Blood then returns through venules, merging into veins that carry deoxygenated blood back to the heart for reoxygenation. Understanding this network is crucial for grasping concepts like blood pressure and tissue perfusion, which are vital for maintaining homeostasis and overall health.

Types of Blood Vessels

In this video, we're going to talk about the major types of blood vessels. So, there are 5 major types of blood vessels that we're going to cover in this video. We can see them numbered in the image all the way around, and they're also numbered in each of these text boxes all the way around as well. Notice that in the center of this image, we're showing you the heart, which serves as a pump that provides the main driving force to propel blood throughout all of these blood vessels. Recall from our previous lesson videos that these blood vessels originate at the heart, they branch off of the heart throughout practically the entire body, but then eventually, they recirculate back to the heart. That is what makes these blood vessels a circulatory network, and we can see this represented in this image down below.

Now the first major type of blood vessel that we're going to talk about are the arteries. The arteries are relatively large and elastic blood vessels that carry blood away from the heart and towards the tissues. The direction that blood is flowing in with respect to the heart is very important when it comes to these blood vessels. Initially, when these arteries branch off from the heart, they are relatively large, about the size of a garden hose. These arteries will continuously branch and diverge into smaller and smaller arteries until eventually, these arteries are considered arterioles, which is the second major type of blood vessel.

These arterioles are really just small arteries, and they are still carrying blood away from the heart and towards the tissues. These arterioles will actually feed blood directly into the capillaries, which is the third major type of blood vessel. These capillaries are the smallest blood vessels of them all. In fact, as we'll learn moving forward in our course, the walls of these capillaries are just about one cell thick. The major function of these capillaries is to facilitate the exchange of gases and nutrients between the blood that the capillaries are carrying and the tissues that immediately surround the capillary. It's very important to keep in mind that the exchange of oxygen and carbon dioxide, and nutrients such as glucose occurs in the capillaries.

After the capillaries, the blood is going to start to make its way back to the heart so that eventually it can be reoxygenated. After the capillaries, the blood is going to collect into venules, which are really just small veins. These venules will merge and converge to form larger and larger venules, until eventually, these venules are considered veins, which is the fifth major type of blood vessel. These veins are the counterpart to the arteries because the veins are blood vessels that carry blood towards the heart.

Once the blood is returned back to the heart, the heart will then pump the deoxygenated blood to the lungs so that the blood can be reoxygenated, and then that reoxygenated blood will be returned back to the heart where the heart will then pump that reoxygenated blood back through the same exact pathway that we just took. This here really concludes our brief introduction to the major types of blood vessels. The last thing that I'll leave you off with here is that, in this diagram, just for the sake of simplicity, notice that the blood flow, the direction of blood flow, is in a clockwise direction. However, in reality, this is not always going to be the case because these blood vessels crisscross throughout practically the entire body. It is possible for blood to be going in a different direction that is not clockwise. However, blood being pumped away from the heart and toward the heart are usually going to be maintained. The reason that I want to bring this up is because later in our course, when we're talking about the capillaries, in order for you to understand content that is important for the capillaries, we are going to change the direction of the blood flow. So instead of blood flowing from the right to the left in the capillary, we will show blood flowing from the left to the right, and that's because you can imagine an artery coming over to this side of the body and coming in like this, and then the capillary, going in this direction, and then a vein coming back and crossing over, something like that. This is totally possible. This concludes this video, and I'll see you all in our next one.

Types of Blood Vessels Example 1

So here we have an example problem that tells us that alveoli are structures in the lungs that help to increase the surface area of the site of gas exchange between blood vessels and the inside of the lung. And then it asks, which type of blood vessel wraps around alveoli? And we've got these 4 potential answer options down below. Now, of course, the key term that's going to help us solve this problem is actually the word "exchange". Recall from our previous lesson videos that it's the capillaries that are very important for facilitating exchange between the blood and surrounding tissues. And so because this is specifically indicating gas exchange occurring between the blood vessels and the tissues of the lung, then of course it must be the capillaries that are found wrapping around the alveoli. So the correct answer to this problem is going to be answer option c, which says "capillaries", and these other options we can eliminate. So that concludes this example, and I'll see you all in our next video.

Which of the following is the route that blood takes as it circulates through the body?

• A. Heart → arteries → arterioles → capillaries → venules → veins → heart. 
• B. Heart → veins → venules → capillaries → arterioles → arteries → heart. 
• C. Heart → arterioles → arteries → capillaries → veins → venules → heart.
• D. Heart → arteries → veins → capillaries → arterioles → venules → heart.

Here’s what students ask on this topic:

What are the major types of blood vessels in the circulatory system?

The circulatory system comprises five major types of blood vessels: arteries, arterioles, capillaries, venules, and veins. Arteries are large, elastic vessels that carry oxygenated blood away from the heart. They branch into smaller arterioles, which lead to capillaries. Capillaries are the smallest blood vessels and facilitate the exchange of gases and nutrients between blood and tissues. Blood then collects into venules, small veins that merge into larger veins. Veins carry deoxygenated blood back to the heart for reoxygenation. Understanding these vessels is crucial for grasping concepts like blood pressure and tissue perfusion.

What is the function of capillaries in the circulatory system?

Capillaries are the smallest blood vessels in the circulatory system, with walls that are just one cell thick. Their primary function is to facilitate the exchange of gases (oxygen and carbon dioxide) and nutrients (such as glucose) between the blood and the surrounding tissues. This exchange is crucial for maintaining cellular function and overall homeostasis. Capillaries connect arterioles to venules, allowing blood to transition from the arterial system to the venous system.

How do arteries and veins differ in their structure and function?

Arteries and veins differ significantly in both structure and function. Arteries have thick, elastic walls to withstand high pressure as they carry oxygenated blood away from the heart to the tissues. They branch into smaller arterioles before reaching capillaries. Veins, on the other hand, have thinner walls and larger lumens. They carry deoxygenated blood back to the heart at lower pressure. Veins also have valves to prevent backflow of blood, ensuring it moves in one direction towards the heart.

What role do arterioles play in the circulatory system?

Arterioles are small branches of arteries that lead to capillaries. They play a crucial role in regulating blood flow and pressure within the circulatory system. By constricting or dilating, arterioles control the amount of blood that reaches the capillaries, thereby influencing tissue perfusion and blood pressure. This regulation is essential for maintaining homeostasis and ensuring that tissues receive an adequate supply of oxygen and nutrients.

Why is it important to understand the direction of blood flow in the circulatory system?

Understanding the direction of blood flow in the circulatory system is crucial for comprehending how oxygen and nutrients are delivered to tissues and how waste products are removed. Blood flows away from the heart through arteries and arterioles, reaches tissues via capillaries, and returns to the heart through venules and veins. This directional flow ensures efficient oxygenation of blood in the lungs and delivery of oxygenated blood to tissues. It also helps in understanding conditions like hypertension and vascular diseases, which can disrupt normal blood flow and impact overall health.