So now that we've covered the different types of blood vessels. In our previous lesson videos. In this video, we're going to focus on blood vessel anastomoses more specifically how blood vessel anastomoses can form collateral channels. And so collateral channels are alternative pathways for blood to reach its same specific destination, which is very important, especially when a blood vessel becomes compromised due to damage such as a cut or due to blockage from a blood clot or the build up of plaque, for example. And so when a blood vessel does become compromised, collateral channels can provide alternative pathways for blood to reach its same specific destination. And usually the amount of blood that is uh supplied by the collateral channels is sufficient to keep the tissue or organ alive until the main pathway that was compromised is restored. Now, when it comes to collateral channels, it is very important for blood vessels to be able to diverge or branch off from one another. However, when it comes to collateral channels, we do not typically focus on the divergence points of blood vessels. And this is because the divergence points of blood vessels do not always form collateral channels. And this is because the diverging blood vessels may actually supply completely distinct areas, tissues or organs and recall that it's only a collateral channel if the alternative pathway allows for blood to reach its same specific destination. And so again, we don't tend to focus on the divergence point of blood vessels when it comes to collateral channels. Instead, we tend to focus on the anastomosis, which is the convergence point or the merging of blood vessels. And this is because the anastomosis or the convergence points or the merging of blood vessels are often going to be a component of collateral channels. And so before we continue, let's take a look at our image down below on the left hand side, which is showing us an analogy. And in this analogy, the train that you can see here represents the blood and the train tracks represent the blood vessels. And notice that this train, the blood here has a final destination that we're indicating down below. And notice that the main pathway or the main blood vessel that the train usually takes to the final destination is actually compromised. It's being blocked by this fallen tree here. And again, this could represent damage to the blood vessel such as a cut or blockage of the blood vessel from for example, a blood clot or the build up of plaque. Uh for example. And so thankfully, collateral channels like the one highlighted here can provide an alternative pathway for the blood to reach its same specific final destination. But again, when it comes to collateral channels, we don't tend to focus on divergence point because notice that this divergence point up above uh the blood vessel is not feeding or supplying blood to the same specific final destination. And uh down below, although this divergence point is part of the collateral channel. More importantly, this collateral channel is merging and converging with this other blood vessel to form the anastomosis, which we have circled in green here. And so we can label this as the anastomosis. And so again, the anastomosis are often components of collateral channels. And so uh this uh route, this alternative route that you can see highlighted here is a collateral channel. Uh thanks to the anastomosis for the most part. And so we can label it as a collateral channel. Now, it is worthy of noting that not all collateral channels will have anastomosis, it is possible to form a collateral channel without an anastomosis. So for example, you can imagine that this blood vessel over here just curled around to the final destination without act, merging or converging or forming any anastomosis, but it's still supplying blood to the same area. And so it's still a collateral channel. And so, although anastomosis are not a requirement for collateral channels, again, they are often components of collateral channels. And this is why anastomosis are important. Now, over here, on the right hand side what we're showing you are the anastomosis of the elbow. So notice that we're focusing in on the forearm here and the arm of this person. And you can see the blood vessels uh going through the elbow joint and around the elbow joint. And it's important to note that this elbow joint has a lot of movement. And so when it has extreme flexion, uh it can actually uh bend and compromise some of the blood vessels um that are in the elbow joint. And so it's very important for the elbow to have collateral channels. So that whenever a blood vessel is compromised, there are alternative pathways for the blood to reach the forearm in our hand to ensure that those tissues constantly receive the blood that they need. Despite what position our elbow might be in. And so anastomoses can really help to form those collateral channels. And so notice that we've got the anastomoses, the converging points of the blood vessels highlighted here in green uh providing those alternative pathways to ensure that our tissues are constantly receiving the blood that they need regardless of what position our elbow is in. Now, the last thing that I'll leave you all off with is that an end blood vessel or a terminal blood vessel is really a non anastomosing blood vessel, meaning that these blood vessels do not ANAs the most or they do not merge or converge to form anastomoses. And what that means is that end or terminal blood vessels do not have collateral channels. So they have very poor collateral circulation. And so if there is the obstruction of an end or terminal blood vessel, that really can result in tissue death. Since these end or terminal blood vessels are the only blood vessels and the only pathways that supply blood to these tissues and organs. And so, organs such as the kidneys, the spleen and the retina of our eye are supplied with end or terminal blood vessels. And so that makes the obstruction of the arteries going to those organs, uh more susceptible to tissue death upon obstruction. And so this year concludes our lesson on blood vessel anastomosis and how they can form collateral channels and moving forward. We'll be able to apply these concepts and continue to learn more about anastomoses as well. So I'll see you all in our next video.
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example
Anastomoses Example 1
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2m
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So here we have an example problem that asks during which scenario would anastomoses be the most important? And we've got these four potential answer options down below. Now, of course, recall from our last lesson video that anastomoses are the convergence points or the merging points of blood vessels that come together. And recall that anastomoses are often a component of collateral channels which provide alternative pathways for blood to reach its same destination. Despite the fact that there could be a compromised blood vessel. And so anastomoses are going to be most important when there's a compromised blood vessel and it helps to form a collateral channel. And so notice that answer option C says when there is a blockage in an artery and of course, the blockage in an artery would be considered a compromised artery since that would inhibit blood flow through that artery. And so the anastomosis could help to form collateral channels that allows for blood to continue to feed and supply the same specific destination despite the fact that there is a blocked or compromised artery. And so answer option C is going to be the correct and the best answer for this example problem. Now, option A says when blood oxygen levels are higher than usual, but really, this has no connection to the anastomosis. So we can eliminate answer option. A option B says during physical exercise and that could be a potentially correct answer. But the best uh and most obvious correct answer is still answer option C so we always choose the best option amongst all options in multiple choice problems. And then answer option D says when the body is at rest, and again, that really doesn't have a direct correlation to these anastomosis. So we can eliminate answer option D. So again, C here is the best answer that concludes this problem.
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Problem
Problem
What is the primary function of anastomoses in blood vessels?
A
Remove impurities from blood.
B
Regulate oxygen levels in the blood.
C
Control blood temperature.
D
Help provide alternate routes for blood flow.
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concept
Types of Anastomoses
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6m
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In this video, we're going to talk about the types of blood vessel anastomoses. So really there are three main types of blood vessel anastomoses that we have numbered down below in our text, 12 and three. And these are the arterial anastomoses, the Venus anastomoses and the arterial venous anastomoses. And so notice that down below in the image, we have a section for each of these three types. Now, the arterial anastomoses as its name implies with the term arterial are going to be convergence or merging points of arteries which recall carry blood away from the heart. And so these arterial anastomoses are commonly found in joints such as the elbow joint and the knee joint, for example, where movements such as extreme flexion, for example, can actually hinder the flow of blood through an artery. And so these arterial anastomoses can help to create collateral channels so that the blood always have an alternative pathway around the joint regardless of what position it's in to ensure that our tissues are always adequately supplied with blood. And also these arterial anastomoses are commonly found near vital organs such as the brain and the heart. For example, where the body really can't afford for the obstruction of a single artery to compromise these tissues. And so arterial anastomosis once again, are commonly found near these vital organs to help create collateral channels to provide alternative pathways for the blood to flow to these organs. These vital organs. So notice down below on the far left side of our image, we have the arterial anastomoses and notice that it is the same exact image that we showed you in our previous lesson videos of the arterial anastomosis of the elbow. So you can see all of these blood vessels running through and by the uh elbow joint here and around the elbow joint and notice uh that the arterial anastomosis are being highlighted here in green. And so those are the convergence or the merging points of these arteries which help to create collateral channels to provide alternative pathways for the blood to flow through or around the elbow joint regardless of what position the elbow joint is in. Now, the next type of anastomoses that we have here are the Venus anastomoses, which as its name implies with the term Venus, which means veins are going to be convergence or merging points of veins which recall carry blood towards the heart. Now, what's really important to note about these Venus anastomosis is that they are significantly more common than any other type of anastomosis. And so because these venous anastomoses are so common, they also create lots and lots of collateral channels in the veins. And so uh veins have very AAA great amount of collateral circulation in comparison to arteries. And because that's the case, generally, the blockage of a single vein is considered far less life threatening than the blockage of an artery. And again, that has to do with the fact that uh these anastomosis are significantly more common, providing significantly more collateral channels and veins. Now down below in the image in the middle, we're showing you examples of Venus anastomoses. Now, veins typically run closer towards the surface of the skin. So you can see actually on the back of the person's hand here, all of these merging and converging uh veins here on the back of this person's hand showing you those venous anastomosis and how common they are now last but not least we have the Arterio Venus anastomosis, which as its name implies, it has a little bit of that arterio root and it also has a little bit of the Venus root here. And so it is really uh exactly what it sounds like. These are going to be convergence or merging points of arteries directly into veins, essentially bypassing the capillaries. Now, this bypassing of the capillaries might sound a little bit familiar to you because recall when we talked about the capillary bed structure of the metas in our previous lesson videos, which recall are the serious membranes of the digestive system that we did talk a little bit about the bypassing of capillaries. And so, uh it turns out that the vascular shunt of the mesentery is an example of an arterio venous anastomosis. And so these arterial venous and asses are common in the meta but also common in areas such as the skin, fingers, toes and ears. And this is really all to more precisely reroute blood flow, giving our bodies the ability to redirect blood flow to other areas of the body when needed. And so notice down below, over here on the far right of our image, we're showing you example of the arterio venous anastomosis. And so, uh again, this top section of the image look really familiar to you from the capillary bed structure of the mesentery that we covered in our previous lesson videos. Uh But notice here that this vascular shunt that I'm highlighting here in green is an example of an arterial venus and as the Moses because it connects this arterial over here directly to the venue over here, uh bypassing the capillaries that you see here since these precapillary sphincters are constricted. But notice that down below right here, we're showing you yet another example of an arterial venous anastomosis, which uh is very similar to a vascular shunt except there is no uh there are no capillaries being shown here at all. And so that's also uh totally a possibility for arterial venous anastomosis. And again, these arterial venous anastomosis are important for helping to reroute blood flow. And so the rerouting of the blood flow uh really does make a lot of these organs more susceptible to uh frostbite because uh under cold conditions, uh the blood is going to be be rerouted away from the skin, fingers, toes and ears. Uh in order to ensure that the blood is rerouted to vital organs uh during cold conditions. So that's really what makes these um areas of the body here more susceptible to frostbite under cold conditions uh due to these arterial venous anastomosis. And so really, this year concludes our lesson on the types of ANAs the moss and moving forward, we'll be able to apply these concepts and continue to learn more. So I'll see you all in our next video.
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example
Anastomoses Example 2
Video duration:
2m
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So here we have a true or false example problem. And the statement says that a blockage in a vein is typically more life threatening than a blockage in an artery. And we've got these four potential answer options down below. Now, recall from our last lesson video that a blockage in a vein is typically less, not more life threatening than a blockage in an artery. And so what that means is that this statement as is is not true, it is false. So we can eliminate answer option A which suggests that it is true. And so notice that answer options, BC and D all start with the word false. Now, recall from our last lesson video that the reason that a blockage in a vein is typically less life threatening than the blockage of an artery is because venous anastomosis are significantly more common than any other type of anastomosis. And so what this means is that having more anastomosis in veins means more collateral channels in veins. And that means more alternative pathways for blood to be able to take in veins. And so that means that the blockage of a vein is going to be less life threatening because there's usually always gonna be another alternative pathway for the blood to be able to take. And so notice that answer. Option B says false blockages in veins tend to be less life threatening as veins have more anastomosis than arteries. And so option B is going to be the best and the correct answer to this example problem. But let's check C and D just to be sure and notice option C says false. Uh But then it says that blockages and arteries are more life threatening because they contain more blood. But recall that the lumens of veins are larger than the lumens of arteries. And that allows veins to hold larger volumes of blood. And at any given time, most of the blood in our body is found in veins. And so uh arteries don't contain more blood than uh veins. So for that reason, we can eliminate answer option C and then answer option D says that uh false. But then it says that blockages in the arteries are more life threatening because they have lower blood pressure. But we know that arteries have higher blood pressure than uh veins which have lower blood pressure. And so uh it's actually the case that uh blockages in the arteries would be more life threatening because they have a higher blood pressure, but that's not what it says. So uh we can eliminate answer option D so again, be here is the correct answer to this problem that concludes this problem and I'll see you all in our next video.
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Problem
Problem
Which of the following is a reason that the retina, kidney, & spleen may be more susceptible to cell death than other organs?
A
Arteries that supply these organs do not have many anastomoses.
B
Veins that carry blood away from these organs do not have many anastomoses.
C
There are very few arteriovenous anastomoses near these organs.