In this video, we're going to begin our introduction to eicosanoids. Now before we get started, let's take a look at our lipid map here to make sure we're all on the same page. And of course, we know that we're currently exploring the fatty acid-based lipids. And already in our previous lesson videos, we've explored the glycerolipids, the sphingolipids, and waxes. And so now we're introducing eicosanoids, another type of fatty acid-based lipid. And so these eicosanoids are really just fatty acid-based lipids that are derived from C20 polyunsaturated fatty acids or unsaturated fatty acids that have multiple double bonds and a total of 20 carbons, like arachidonic acid for instance, whose shorthand name we're providing here. And so many of these eicosanoids are derived, specifically from this arachidonic acid. Now the name eicosanoids is actually derived from the Greek word "eikosi", which means 20. And so this speaks to the C20, polyunsaturated fatty acids. Now there are really 3 main classes of eicosanoids that we're going to talk about moving forward and these are the prostaglandins, thromboxanes, and leukotrienes. And so moving forward, we'll talk about each of these 3 different types of eicosanoids in their own separate videos. But if we take a look down below at our image, notice we're showing you the structure of arachidonic acid, which you'll notice is a C20 polyunsaturated fatty acid. It's a fatty acid because it has a carboxylic acid and a long chain hydrocarbon, and there are exactly 20 carbon atoms, and it is definitely polyunsaturated because there are multiple double bonds. And arachidonic acid again is going to be, the precursor to all of these other eicosanoids that we see down below. The prostaglandins, thromboxanes, and leukotrienes. Again, which are all eicosanoids. And so, in our next lesson video, we'll be able to talk about, the general function of these eicosanoids and then we'll talk about each of these 3 individually in their own separate video. So I'll see you guys in our next video.
Eicosanoids: Study with Video Lessons, Practice Problems & Examples
Created using AIEicosanoids are fatty acid-based lipids derived from 20-carbon polyunsaturated fatty acids like arachidonic acid. They function as paracrine hormones, signaling nearby cells and acting at low concentrations. The three main classes of eicosanoids are prostaglandins, thromboxanes, and leukotrienes. Prostaglandins regulate pain, fever, and inflammation; thromboxanes are crucial for blood clot formation; and leukotrienes, produced by leukocytes, can induce smooth muscle contractions, impacting conditions like asthma. Understanding these functions is essential for grasping their roles in physiological processes.
Eicosanoids
Video transcript
Eicosanoids
Video transcript
In this video, we're going to talk about the functions of eicosanoids. Eicosanoids actually have a wide variety of functions. They have so many different functions that we're not going to be able to talk about all of their different functions. But one thing to note about eicosanoids is that they usually act as special types of hormones. Now, I'm sure all of you have probably heard of the word hormones before but what exactly are hormones? Well, hormones are really just defined as bio signaling molecules. So, they allow cells to communicate with each other and to affect each other. More specifically, these bio signaling molecules are going to be released by a cell or a gland and can actually travel and affect distant cells in a completely different area of the body. Now, again, eicosanoids act as special types of hormones and so, really, eicosanoids are going to function as what are known as paracrine hormones. This paracrine here is just hinting at the fact that they still act as signaling molecules, but they do not travel and affect distant cells in other areas. Instead, paracrine hormones act only on nearby cells in the vicinity of their synthesis. This allows eicosanoids to act or function at very, very low concentrations. You don't need a lot of eicosanoids in order to get a function. And these eicosanoids, they actually tend to decompose within just a few seconds or minutes. And really, that's what limits their travel and allows them to function as paracrine hormones. Now again, moving forward in our course, we're going to talk about the three different types of eicosanoids, starting with prostaglandin. So I'll see you guys in that video.
Eicosanoids
Video transcript
In this video, we're going to talk about our first class of eicosanoids, which are the prostaglandins. Prostaglandins are commonly abbreviated as just PG. The reason they're called prostaglandins is because when they were first discovered, they were isolated from the prostate gland, but it turns out that they're actually way more prevalent in other tissues other than the prostate gland. These prostaglandins are just eicosanoids that contain a 5-carbon ring or a cyclopentane ring. Prostaglandins are eicosanoids, and "eicosy" means 20; this means that they are derived from \( C_{20} \) polyunsaturated fatty acids like arachidonic acid. You can see here in our image that arachidonic acid is the precursor molecule for prostaglandins such as prostaglandin \( E_2 \) here, whose structure we're showing you. Prostaglandins contain 5 carbon cyclopentane rings, and so you can see the cyclopentane ring right here. You could think the "p" here in prostaglandin is for the "p" in the cyclopentane ring, and hopefully, that will help you remember that prostaglandins are eicosanoids with a cyclopentane ring.
In terms of the functions of prostaglandins, they have many different types of functions. We're not going to be able to get into all the different functions of prostaglandins. Some of their primary functions include regulating pain, fever, and inflammation, as well as affecting blood flow and smooth muscle contractions. Just as a reminder of their role in regulating pain, fever, and inflammation, we have an image here of a sick kid who's got a thermometer in his mouth and is trying to regulate his pain, fever, and inflammation.
This here concludes our introduction to prostaglandins, and in our next lesson video, we'll be able to talk about our second type of eicosanoid, which are the thromboxanes. So, I'll see you guys there.
Eicosanoids
Video transcript
In this video, we're going to talk about our second class of eicosanoids, which are the thromboxanes. Now thromboxanes are again a specific class of eicosanoids that have, instead of a 5-membered ring like prostaglandins, they actually have a 6-membered ring with an ether group. And again, because thromboxanes are eicosanoids, and eicosi means 20, these are derived from C20 polyunsaturated fatty acids, such as arachidonic acid. And so, arachidonic acid is the precursor to thromboxanes such as thromboxane A2 over here. And notice that the thromboxanes do have 6-membered rings just like this one right here. And the 6-membered rings also have ether groups like this blue one that we see right here. One way that helps me remember that thromboxanes have 6-membered rings is that I think about a box that has a hexagon shape or 6 sides. And so, by thinking about the box, it helps me remember that this is going to be a 6-membered ring or include a 6-membered ring. Now, the reason that thromboxanes are called thromboxanes is because they're actually produced by platelet cells, otherwise known as thrombocytes. And so, thrombocytes or platelets, they play a big role in the formation of blood clots. And that's because the thromboxanes that they produce will help to initiate blood clot formations. And thromboxanes are also important for reducing blood flow to the clot. And so, if you ever get injured and get a cut, it's important for your blood to be able to create a clot to make sure that you do not lose too much blood. And again, the thromboxanes are very important in this process. And so this here concludes our introduction to thromboxanes. And in our next video, we'll be able to talk about the 3rd class of eicosanoids, which are the leukotrienes. So I'll see you guys there.
Eicosanoids
Video transcript
In this video, we're going to talk about our 3rd class of eicosanoids, which are the leukotrienes. And so, leukotrienes, of course, are eicosanoids, and as their name implies, the 'tri' indicates that there are 3, and the 'enes' are indicating the presence of double bonds. And so indeed, leukotrienes are eicosanoids that have 3 conjugated double bonds. And, of course, because these are eicosanoids and the Greek word 'eikosi' means 20, leukotrienes are derived from C20 leukotriene D4 whose structure we're showing you here. And again, leukotrienes as the name implies, they have 3 conjugated double bonds. And so when you take a look at the structure here, you can see that these 3 double bonds right here are conjugated double bonds. And so there are 3 conjugated double bonds. Now by conjugated, really what we mean is that they're just appearing back to back here, in this particular fashion. Now notice that this double bond down here is not conjugated because it's being separated from the others by a CH2 group.
And so the reason that leukotrienes are called leukotrienes is because they're predominantly expressed by leukocytes, which is really just the scientific name for white blood cells. And so our white blood cells produce these leukotrienes. Now, the leukotrienes actually have variable functions, but they predominantly act as powerful biosignals. For example, leukotriene D4 will actually induce strong smooth muscle contractions of our lungs. And of course, in some people, allergic reactions can trigger leukotriene synthesis. And so if leukotriene D4 is being synthesized, or overexpressed, it's going to induce strong smooth muscle contractions of the lungs. And that could lead to an asthma attack. And so, if you know people that have asthma, it's really because of the allergic reactions are causing them to over create leukotrienes, specifically leukotriene D4. And so, down below in our image, notice that we've got this guy right here, who is having an asthma attack because of the overproduction of leukotriene D4. And, notice that he's using this inhaler here and the inhalers will actually have specific molecules that block receptors for leukotriene D4. And so that's just something interesting, to note.
But really this here concludes our introduction to leukotrienes and moving forward we'll be able to apply these concepts that we've learned in our practice problem. So I'll see you guys there.
Which of the following fatty acids is the precursor to the eicosanoids?
A) Arachadonic Acid.
B) Palmitic Acid.
C) Steric Acid.
D) Oleic Acid.
E) Carboxylic acid.
Which of the following is true regarding eicosanoids?
A) All eicosanoids contain three conjugated double bonds.
B) All eicosanoids contain arachidonic acid and sphingosine.
C) Prostaglandins and leukotrienes both contain a ring structure.
D) Thromboxanes, prostaglandins & leukotrienes all contain a carboxyl group.
Prostaglandins are local regulators whose chemical structure is derived from:
A) Oligosaccharides.
B) Fatty Acids.
C) Steroids.
D) Amino Acids.
E) Isoprenoids.
Non-steroidal anti-inflammatory drugs (NSAIDS), like aspirin & ibuprofen, lower body temperatures by blocking production of which eicosanoid?
A) Biological waxes.
B) Prostaglandins.
C) Sphingolipids.
D) Vitamin D.
E) Cholesterol & other isoprenoids.
Here’s what students ask on this topic:
What are eicosanoids and how are they derived?
Eicosanoids are fatty acid-based lipids derived from 20-carbon polyunsaturated fatty acids, such as arachidonic acid. The term 'eicosanoid' comes from the Greek word 'eicosi,' meaning 20, which refers to the 20 carbon atoms in these fatty acids. Eicosanoids function as paracrine hormones, meaning they act on nearby cells rather than traveling to distant parts of the body. They are synthesized from arachidonic acid through enzymatic pathways, leading to the formation of three main classes: prostaglandins, thromboxanes, and leukotrienes. Each class has distinct structures and functions, playing crucial roles in physiological processes like inflammation, blood clotting, and smooth muscle contraction.
Created using AIWhat are the main functions of prostaglandins?
Prostaglandins, a class of eicosanoids, have several important functions in the body. They are involved in regulating pain, fever, and inflammation. Prostaglandins also affect blood flow and smooth muscle contractions. For example, they can cause vasodilation or vasoconstriction, influencing blood pressure. Additionally, prostaglandins play a role in the induction of labor by promoting uterine contractions. Their diverse functions make them key players in various physiological and pathological processes, including the body's response to injury and infection.
Created using AIHow do thromboxanes contribute to blood clot formation?
Thromboxanes are a class of eicosanoids that play a crucial role in blood clot formation. They are produced by platelet cells, also known as thrombocytes. Thromboxanes have a six-membered ring structure with an ether group. They help initiate the formation of blood clots by promoting platelet aggregation and vasoconstriction, which reduces blood flow to the site of injury. This process is essential for preventing excessive blood loss when you get a cut or injury. Thromboxanes are thus vital for maintaining hemostasis and wound healing.
Created using AIWhat role do leukotrienes play in asthma?
Leukotrienes are a class of eicosanoids predominantly produced by leukocytes (white blood cells). They have three conjugated double bonds and are involved in various immune responses. In the context of asthma, leukotrienes, particularly leukotriene D4, induce strong smooth muscle contractions in the lungs. This can lead to bronchoconstriction, making it difficult to breathe. Allergic reactions can trigger the overproduction of leukotrienes, exacerbating asthma symptoms. Inhalers used by asthma patients often contain molecules that block leukotriene receptors, helping to alleviate these symptoms.
Created using AIWhat is the difference between paracrine and endocrine hormones?
Paracrine and endocrine hormones are both types of signaling molecules, but they differ in their range of action. Paracrine hormones, like eicosanoids, act on nearby cells in the vicinity of their synthesis. They do not travel far from their site of production and function at very low concentrations. In contrast, endocrine hormones are released by glands and travel through the bloodstream to affect distant cells and organs. Examples of endocrine hormones include insulin and thyroid hormones. The key difference lies in the distance over which they exert their effects.
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