Skeletal Muscle Anatomy

in this video, we're going to begin talking about skeletal muscle anatomy so muscle contractions are accomplished by molecular motor protein interactions. And so the motor protein Maya Seuin is responsible for pulling on thin acting micro filaments during a muscle contraction, and muscle contractions and skeletal muscle tissue are one of the best understood mobility systems. And so for that reason, we're going to talk about the muscle contraction in skeletal muscles later in our course. But before we can talk about muscle contractions and skeletal muscles, we first need to understand skeletal muscle anatomy. And so in our next video, we'll talk more about skeletal muscle anatomy, so I'll see you guys in that video.

in this video, we're going to talk about skeletal muscle anatomy and so notice down below. We have an image showing you skeletal muscle structures, and it ties together nicely with the text that we have up above. And so we're going to start with the far left structure that we have highlighted here, which are referred to as Sark Amir's. So Sarka beers are complexes of thick myosin filaments and thin acting micro filaments that are in special arrangements. And so later in our course, in our next lesson, video will be able to talk Maura about the structure of the SAARC Amir and these special arrangements that thes thick and thin filaments are in. But for now, if we take a look down below, it are image. We can see that these brackets that we see here and here are labeling the SAARC Amir's. And so this one bracket is labeling one sark amir, and this one is labeling another Sark amir. And so there's actually another Sark amir here and here and here. And so these repeating units of SAARC Amir's are referred to as my oh fiber ALS. And so these myo fire rolls again are repeating units of SAARC Amir's. And so if we take a look at our image down below, we can see that this entire thing right here would be referred to as the Myo Fiber all and notice that here we have another Myo Fibra. Here's another one. Here's another one And here's another one. And so together all of these myo Fibras which will notice, is that they are surrounded by what's known as a Sarko plasmid Ridiculous, which is a membrane ISS structure and so down below noticed that this yellow structure that we see here that's being labeled as the Sarko plasmid ridiculous um is, uh, actually going to be very, very important when it comes to a muscle contraction. And so later in our course, when we're talking about muscle contractions, we are going to talk up. We are going to revisit this Sarko plasmid Ridiculous um which is going to be important for releasing calcium, But again, we'll talk more about the circle plasma Ridiculous, um, and the calcium that it releases later in our course when we're talking about the muscle contraction. But for now we can see that the Sarka plasma ridicule, um, is uh, the yellow membrane. A structure that we see here. Uh, now, what you'll notice is that, uh, these myo fiber ALS that we see here are all packed inside of what's known as a muscle fiber. And so a muscle fiber is just a long multi nuclear gated cell. And so multi nuclear it it just means that it has multiple nuclei. So instead of having just one nucleus, like most cells, thes muscle fibers have multiple nuclei. Multiple nucleus is if you will. And so what you'll see is that here, what we have is the muscle fiber, and so you can see that this is all one really, really long cell, and so it is quite long, and it it can actually run the length of the entire muscle. So that is quite long for one individual cell. And again, they are multi nucleotide. So you can see that each of these blue structures that we see here represent nuclei and they're going to repeat and be within, uh, this muscle fiber. Now again, you can see that within the muscle fiber, the myo fiber ALS are gonna be packed inside and extend the length of the entire muscle fiber. Now, notice that this entire muscle fiber that we see here is leading up to what's known as a mussel, uh, fast ical. And so this muscle fast ical all it really is what we can see here. It's just a bundle of muscle fiber. So it's just a bundle of individual cells, a bunch of thes long, multi nucleotide cells packed together. And so what you'll notice is that a bunch of these, uh, here here. We only have one muscle fast ical, but you'll notice Here's another muscle fastball. All of these are muscle fast sickles, and so, ah, bunch of muscle fast sickles are gonna make up the skeletal muscle. And so the skeletal muscle are gonna be the voluntary muscles the ones that we actually have control over, such as our biceps, for instance. Uh, here and they are going to have a striated or striped appearance and the striped appearance that you can see through out here where you have a dark band followed by a light band followed by dark band. Uh, this is the striated striped appearance, and really, it all comes down to the structure of the SAARC. Amir that gives the skeletal muscle this striated striped appearance. And again, the skeletal muscle is going to consist of muscle fast sickles coming together. And so you can see here we have the human body, and you can see the skeletal muscle that scattered throughout. And so we can label this as the skeletal muscle. And so, really, this completes our lesson on skeletal muscle anatomy. And again, in our next lesson, video will be able to talk Maura about the structure of these Sark Amir's, and later we'll be able to talk about the muscle skeletal muscle contraction, so I'll see you guys in our next video.

in this video, we're going to focus on Sark. Amir's So Sark Amir's are important because a muscle contraction is actually the result of a Sark Amir contraction. And so later, in our course, we're going to talk about SAARC, Amir and muscle contractions. But before we can do that, we need to understand the structure of a Sark Amir and so a single Sark Amir actually has several different regions and components, and we're going to talk about all of those regions and components down below here, in our text. Now, notice that the text is actually color coordinated to match the regions and components down below and our image and so notice up above here. What we have is the same exact visual representation of the SAARC Amir that we had in our last lesson video. And so really, what we're doing here is we're zooming in on this specific region of the SAARC Amir and we're blowing it up and visually representing it in this representation that we have here. And so if we go up to our text, we can focus on the first region here, which is right here, and this is going to be the H zone. And so what helps me remember what the H zone is is I know that the letter h is quite a thick letter. It extends a lot horizontally from side to side. And so because the letter h is such a thick letter, the H zone is on Lee going to contain thick my ascend filaments and it will have no overlaps with thin acting micro filaments at all. And so if we take a look down below at the image of our Sark, Amir noticed that the thick myosin filaments are in red right here. And of course, the thin acting micro filaments are in green at these positions on either side. And so, of course, the H zone. Because H is such a thick letter that reminds us that, uh, the H zone is on Lee going to contain thick myosin filaments. And so notice that this region here, highlighted with a blue background, contains Onley, thick myosin filaments and no overlap with any of the thin acting micro filaments. And so because that's the case, that makes it the H zone and so we can label this region down below indicated by this bracket right here as theme H zone. And so now we can move on to the next region and so the next region is going to be the I bands. And so because the letter I what helps me remember what the I bands are is that because the letter I is such a thin letter That reminds me that the since I is such a thin letter that the I band is on Lee going to contain thin acting micro filaments and it will have no overlaps with thick myosin filaments at all. And so if we take a look down below at our image uh, notice that the region that Onley contains thin acting micro filament is going to be this region over here and as well uh, over here. And so this region contains Onley thin act in micro filament. So the thin letter I reminds us that this is gonna be the I banned So from this region to this region over here and over here, from this region to this region over here now the next region that we have is referred to as the A band. And so it helps me remember what the A band is is that the letter A is actually mostly a thick letter, but towards the top, it's actually quite thin. And so because the letter A is mostly thick but has a little bit of thin, this means that it's going to contain all of the thick myosin filaments on some acting filaments as well. And so if we take a look down below at our image theme a ban again because A is mostly a thick letter and something it's gonna contain the entire length of the thick Meyssan filaments. But notice that there's also going to be some overlap with thin acting micro filaments as well. And so the a band is really just going to be this entire region that we see here really just defined by the length of the thick myosin filaments. And so you can see that this yellowish background that we have that extends from here to here, indicated by this bracket down below, is going to represent our A band. So now we can move on to the next component, and so the next component that we have is the M Disc or the M line, for that matter, and so Sometimes they will be referred to as the M discs. Other times they will be referred to as the M line. But what helps me remember what the M disc or M line is is that the letter M is for the middle. And so this is going to be a vertical anchor to Myson in the middle of the entire Sark Amir in terms of being in the middle of the H Zone and the A band and so down below. What you can see is that the M Disc is this disc shaped structure that we see here in the center so we can go ahead and label it as the M Disc and notice that the M disc is in the middle of the entire Sark Amir present in the middle of the H Zone and the middle of the A band. And it's also a vertical anchor to the thick myosin filaments so you can think M disc for anchoring the myosin filament. So then, last but not least, what we have are the Z discs, also known as the Z lines. And so what helps me remember what the Z discs or the Z lines are Is that because E is the last letter of the alphabet, the Z disk is going to mark the end of a Sark Amir. But because the SAARC Amir's are repeating units, the end of a Sark Amir also marks the beginning or the start of another Sark Amir. And so Z discs marked both the start and the end of a Sark Amir. And really, what you can see down below is that these purple structures that we see on either end these purple disks represent the Z discs. And so one single Sark Amir actually has two Z discs on either end and a Sark amir can be defined from the region from Z disk to Z disk. And so the Z discs are important because they are vertical anchors to the acting thin micro filaments and the Z discs are going to be centered on the I Band. Uh, on dso What you'll notice is that, uh, here, what we have is the i band, and, uh, this is one, um, SARC amir here. But if we had a neighboring Sark amir, there would be another I band over here. And so the Z disk here would be centered on the I band and the same goes for over here. There would be another I band here, and so the Z disk would be centered between the I Band. Now again, the Z discs are vertical anchors to the acting. So the acting micro filaments that we see here are anchored, uh, to the Z discs, and so that's important to keep in mind. And so, really, this is the structure of a Sark Amir, and we'll be able to get some practice utilizing the concepts that we've learned here in our next video, so I'll see you guys there.