Okay, hyaline cartilage, which joint represents hyaline cartilage? Yes, what does chondro mean? Cartilage. Okay.
Okay. Immovable in adults. So there's a few up there that can be immovable.
However, it's held in place by a ligament and it's immovable. So there's two factors. What shouldn't move that's in your mouth?
Teeth. And what kind of sounds like gums? Gomphosis.
Now syndesmosis is held in place by a ligament, but syndesmosis is slightly movable. Okay, identify the functional classification of the pubic synthesis. Amphi, yep. And then what is the structural? I just told you the name of the joint.
Synthesis. So what it's pointing at is the pubic synthesis. Structurally, that's cartilaginous, but even more specifically, it's a synthesis. Okay, what joint disappears when we disassemble it?
stop growing in length it is your epiphyseal plate but which of those four words represents the epiphyseal plate what is the epiphyseal plate made out of what kind of cartilage what kind pylon and what was the first answer for nuchal chondrosis okay so this chapter it's not that it is as difficult as other chapters you all covered It has the most confusing vocabulary in it. So you really got to get this vocabulary down. Okay. I have a lot of extra work online for y'all to do just for practice.
No grades, but it might help you with the vocabulary aspect of it. I'm glad I gave y'all one more day for studying. Okay, now all I can say is I know we're starting chapter 10 and it's not on your test But this test 3 material is the most important material for a mp2 So everything that we cover in test 3 is the full foundation Because we're covering muscles and nervous system and how they signal and how they contract and work together A&P 2 is cardiovascular respiratory digestive You know lymphatic immune. All of those rely on sending signals, contractions. So it's super important that you get the basis of it here.
So this is a tough test, but it's actually probably the funnest test for you all because the information is much more enjoyable. So you actually start to see processes and how they come together. And it relates back to stuff that you already know, because we covered it in one through nine. Okay. So we are talking about muscle.
Muscular tissue, when you think about muscles, what do you think about? Movement, okay? Muscles have a lot of function, but one of their main functions is going to be movement.
However, there's lots of different types of movement, so we're going to talk about what their main function is. Now, we have three muscles, skeletal, cardiac, smooth. This chapter focuses primarily on skeletal. So as we go through, I might forget to say skeletal muscle.
I might just say muscle, but what am I referring to? Which muscle? Skeletal.
We will cover very little on cardiac and smooth because that is stuff that you're going to get heavily in A&P 2, but we'll give a brief intro in A&P 1 to it. Okay, we already went over the three muscle types when we went over the material in chapter four. So this right here is just a review of this material. So this is a chart that I gave y'all in chapter four when we talked about the muscles.
Bless you. Skeletal muscle, striated, multinucleated. Do you control when you write, talk?
Okay, so we control this muscle, so skeletal is voluntary. Smooth muscle gets its name because it lacks stripes. Do you control your digestive tract? Okay, do you control blood vessels moving blood through the body? So do we control smooth muscle or not?
So it's involuntary. And then where's the only place we find cardiac? In your heart.
Do you control your heart? Nope, so it's involuntary. So this is just stuff to go back to a review of chapter four. Okay, oh, wait, where did my clicker stuff go? Hold on, give me a second.
Okay. get those clickers ready you may have to hit refresh so everyone double check their answers most people are partially right or fully right so just double check what you're putting through all the options ah good changes okay okay skeletal muscle is it involuntary is smooth muscle involuntary is cardiac muscle involuntary so what answer does it need to be e b and c so some of y'all had just b and some of y'all just c when i said that most of y'all changed so it's about reading through all your choices never stop at the first correct answer always read through everything okay so i wish i could sing because i would sing to y'all there is a bad and i don't mean bad like in like explicit lyrics just bad as in bad 90s rap song by paperboy called the ditty and it says do the ditty itty if you want to no one's ever heard it right okay it's a really bad rap song but every time i teach this it's all i think about is the ditty song because ditty rhymes with itty and these are four of the main characteristics of any muscle in your body what do they all end in they all end in itty so i always think of that song when I teach this stuff. So we already actually know most of these terms. These four terms describe all three of our muscles, skeletal, cardiac, and smooth. But which muscle are we really concentrating on in this class?
Skeletal. Okay, so what do we know extensibility means? To extend, which means basically are we getting smaller or longer?
Longer. So extensibility describes that all muscles can actually stretch. So you can see if you look in that picture closely, you'll see that the rubber band's being pulled apart. But anything that stretches, what do we want to make sure it does?
Recoils. And which word does that describe? Elasticity.
Now. You told me earlier that the main function of muscle is movement and that's very true. But stretching is actually movement. But when we think about muscle movement, we actually think that muscle shortens to produce an actual movement. So which word up there is going to be shortening of a muscle?
Contractility. Now none of this can happen to muscles. unless we send an electrical signal to them.
What other tissue in your body can send electrical signals? Nervous tissue. So we have to be able to send an electrical signal to muscle tissue.
So what word tells us that muscle tissue can conduct electrical signals? Excitability. What do all these words have in common? It is.
So these are four... characteristics of all muscles but we are concentrating on skeletal. Okay get those clicker, oh wait not yet.
So this is just a picture. Okay this picture right here shows a muscle going from what we consider resting which is normal length and then it got shorter. What word describes normal to shorter?
You got it contractility which is contraction. I just threw the ah itties at the end so you can make sure we have a way to remember them. Okay, look at this. Here's a lovely neuron. sending an electrical signal to the muscle what's that okay here is a resting muscle that gets stretched which one's that and here is a muscle that is shortened but now it returns to its original length you got it okay so different ways to remember it that's why i try to give you all these kind of i call them like silly stupid ways to remember stuff but it helps with connections content that you're learning.
So you're learning such a mass amount of material at once. Okay. Now something that's kind of cool about skeletal muscles is they are the only muscle that is multinucleated. What does that mean? Multinucleated.
A lot of nuclei. Okay. So how does this happen? It's happened in the development of the muscle.
So it's happening when you are developing in the womb. Now let's go back to chapter four. Everyone loves chapter four, but you can see how much I refer to it.
Which germ, what rhymes with germ? Which germ tissue does most muscle come from? Mesoderm. Okay. So we are going to start off with some mesodermal tissue.
Mesodermal tissue will produce cells called myoblasts. What is myo gonna mean to us? It means muscle to us.
Okay, what does blast mean? So what are myoblasts building? Good job y'all.
Okay, so mesoderm is going to produce myoblasts. So in this picture I think there's three myoblasts, so let's just go with that number. These myoblasts are going to fuse together when they fused together, notice that we're going to have multiple ones kind of just coming together and they're all maintaining their nuclei.
As they fuse together, the myoblasts are going to form an immature skeletal muscle cell. So we have our myoblasts. They're going to start to fuse together.
And when they fuse together, we get our immature skeletal muscle cell. Now, apparently a little another myoblast joined the party because now there's four. But when they fuse together, if we look here, we have one nucleus, two, three, four. Okay. Do you think it's going to be easy for these nuclei to coordinate mitosis.
They're four separate nucleus. Do you think it's going to be easy for all four of them to say, let's do mitosis at the exact same time? So once you are born, skeletal muscle fibers lose the ability to divide or produce new cells.
So no more division once you're born. And that whole point is because it's too hard to coordinate hundreds of nuclei to do the thing at the exact same time. Everyone's seen like a flash mob, like in videos. Everyone's trying to do the exact same thing at the exact same time. Skeletal muscle cells can't do that.
So once they fuse together, they basically lose that ability. So when you're born, you have the set number of skeletal muscle cells that you're going to have through life. It is. But we're this big.
What happens to us over time? We get bigger. Skeletal muscles cannot produce new cells. They can only grow in size.
Y'all remember that term, growth in size? Hypertrophy. Okay. So y'all remember that?
We did this with balloons. Okay. So skeletal muscle cells can only get... larger in size. That's how we grow.
That's how our muscles accommodate your growth and body size. The skeletal muscle cells get larger in size. They cannot produce new cells. Do y'all remember that term for production of new cells? It is proliferation, but it's specifically hyperplasia.
So you remember how little gizmo gets wet and produces evil gremlins? Okay, we can't do that. So once our muscle cells are there, no more new cells, only growth of those cells.
So they can get bigger in size, but they cannot produce new cells. We're going to go back to that. So again, everything that we're learning in previous chapters, do you think it's really important? Yeah, I'm not just teaching this to y'all for my own benefit.
and I try to keep themes throughout. So we now know gremlins really well. If y'all haven't watched that cult film, you gotta go watch it.
Okay, now I'm gonna go back to this picture again. You'll see those little satellite cells there. Okay, basically these are myoblasts.
So they're modified myoblasts. Satellite cells can fix minor repairs to muscle cells, minor. So if you tear your skeletal muscle if it's a really bad tear you're gonna either get scar tissue or you're gonna have to have surgery if you have like a minor tear nothing bad you don't even notice it may just be a little sore a satellite cell can fix that so they're modified myoblasts that can do very minor repairs and if you think about a satellite they kind of orbit around the earth these satellite cells are kind of orbiting around the muscle cell have you all ever seen shark week or any of those like marine shows you know how like the big whales and even sharks have feeder fish that live on them that's kind of how i think of the satellite cell it just kind of hangs around it helps out if needed but the benefit to the actual animal is even minimal because it can't do too much for that muscle cell. Okay, so yes we can get bigger in size, no we cannot produce new cells.
Okay, let me get this out of the way so y'all can see it. on the that went far okay talk it out with your partners keep talking it out i'm seeing a shift Okay, okay. I like that you're suggesting and talking to each other.
A muscle scale can stretch up to two times its length. What does elasticity tell us? Recoil. So what would make this true?
Extensibility. So the answer for this particular question is false. Here's another one. Okay, missing one person got it in.
Perfect. Okay, everyone got it right. Grow in size by what?
But smooth muscle can actually make new cells, which is hyperplasia. Now, not all smooth muscle can make new cells. Most can. Think about people that have heart attacks.
Part of their heart usually dies. Can they make new cells? Now, they have had... discoveries that cardiac cells, cardiocytes, can make new cells, but the time it takes is years, so it's not beneficial for the person that went through the heart attack. So, yeah, so basically cardiac cells go through hypertrophy very easily because you've heard of enlarged hearts.
In general, they cannot produce new cells. There is research behind that they have the capabilities, but the timeline's not good. A large heart, that's just hypertrophic. So sometimes your heart, like most athletes, especially professional athletes, hearts actually larger than average sized person, because your heart's going to grow in demand to how much work you make it do.
Now some people, there are diseases where the heart actually grows too large and your body can't handle it. And that usually puts people in early cardiac failure. But if you know that you have an enlarged heart, there's usually medicine that can help. And you can live a normal life. You just can't be as active.
And bless you. And when we talk about activities, we're talking about you can still do stuff, just not, you know, professional levels. There are a lot of professional athletes that have to stop because what made them so good when they were young was that they could pump blood faster and more of it.
And then as they got older, they started having the complications. Yes, so if they don't want to die young, they need to stop having all that exertion. But yeah, it definitely can put a limit on your lifespan.
It can affect it. But we are living way longer than we used to. How many people are 90s and 100s now? So I think 70 might be a good age.
You're still like vibrant, but you can't do as much anymore. Okay, so what we're about to start talking about is skeletal muscle structure. I am going to go over some stuff that is important for you to understand so you have an idea of how your body's organized.
I necessarily do not care if you memorize any of it. It's more about you understanding that where all the action is happening is microscopic, but everything looks alike. So to understand what's happening microscopically, you have to know where it is in your body. So we're going to go through the organization from big to small.
It's going to help you to write it down, but you don't necessarily need to memorize everything. Okay. So what we have here is we have a skeletal muscle and it's attached to the bone. What's attaching this muscle to the bone? Tendons.
Okay. So we see that we have this tendon here. Let me move this out of the way. So we see that we have this tendon here. Okay.
Tendons are actually going to be... a combination of three different connective tissue coverings. So all of these connective tissue coverings that are in a muscle are going to extend past the muscle to form the tendon. So every covering that's in a muscle will extend past the muscle and form the tendon. Most tendons in your body are made at a dense regular, which means they're super strong in that direction.
If you don't know the largest tendon in your body, it connects your calf to your heel. Achilles. That's the common name for it, but calcaneal tendon, gastrocnemius tendon. all our names for it too mostly made of dense regular because some tendons are sheets that cover big spots and those are going to be dense irregular but most the ones that we talk about are dense regular okay so if you look let me erase all this ink so if we look here what we're going to start noticing is that this muscle is circular Inside the muscle, we have all of these circles. Inside those, we have these little circles.
And inside those, we have little circles. So everything looks alike in a muscle. But there's different layers.
And the layers are what we're going to want to learn. Okay, so the first thing is we have our entire skeletal muscle. And you notice that it's covered by the epimysium.
I don't care if you write that down. I don't. But we have our skeletal muscle.
Now do you see inside the skeletal muscle we have these groups of circles? These groups of circles are known as fascicles. So we have skeletal muscles. They are made up of fascicles. In this picture, there looks like there's about 10 fascicles.
Now do y'all notice that inside each fascicle we have little circles inside of them? Okay, these are known as muscle cells. So, skeletal muscles are made up of groups called fascicles.
What are fascicles made up of groups called? Muscle cells. Most of the action we talk about is at the muscle cell level. So, it's a really tiny level that we're going to be concentrating on. and it's microscopic but I like so y'all can see where it is in your body.
So you know when you cut meat, has anyone cut a steak and it's a little stringy? Okay, those strings are the fascicles that you're cutting. Okay, inside the fascicles what are you actually eating inside of them?
The muscle cells. Okay, now if you notice all of them are covered by something, a mysium, endo, peri, epimycem. Those are those three coverings that form what?
What attaches a muscle to a bone? So they're covering each of those layers, and they extend past the muscle, and they form the tendon for us. Okay, now I want you to look really closely. It may be hard to see, but do you all see a little bitty thread sticking out?
Okay, muscle cells are going to be made up of myofibrils. I'm going to go to a bigger picture in a minute. Muscle cells are made up of myofibrils. So if I bundle a lot of myofibrils together, they're going to form what structure?
A muscle cell. If I bundle lots of muscle cells together, what do they form? And when I bundle fascicles together, we form our skeletal muscle. Okay, so all we're looking at now is one enlarged fascicle. So this is just one fascicle.
I don't have to get lots of fascicles together for a muscle cell. Inside each of these fascicles, we have lots of what? Okay, inside the muscle cells, what are these little, I call them straws.
What are these little guys? You got it. Now, do y'all see these little threads sticking out?
Myofibrils, I'm going to go back to this page, are going to be composed up of protein fibers. Now, we are not there yet in this lecture, but on that packet that I printed for y'all, there's a chart. Those are all the protein fibers y'all are going to be learning.
So there's not just one protein fiber y'all are learning. There is a whole list of these protein fibers. Okay.
I know that this kind of is confusing, but it's really important that you understand from big to little. Okay. How many of y'all have seen the little stacking dolls? So this is exactly how I think of muscle cells and like skeletal muscles.
They all look alike. they're just different sizes so the largest is the biggest that is your skeletal muscle cell oh sorry just your skeletal muscle what are skeletal muscles made up of fascicles what are fascicles made up of what are muscle cells made up of before protein fibers Myofibrils and then what are myofibrils made up of? You got it.
They all kind of look alike? Yeah, but it's about their size and where they're located in the body. You can see skeletal muscles with your naked eye.
When people flex, when people work out, everybody take a look at the back of their hand and just start making a fist. Do y'all see y'all's tendons moving? What are y'all's tendons attached to? And what else? Muscle.
So you may not actually see the muscle but you can see the tendons. Oh you know if you start like moving your wrist and doing stuff like that you can start to see the muscles contract. Yes.
That is going to be about ions that we're going to talk to you talk about. So how muscles contract is all about movement of ions in your body and if you don't have the right amount of ions it's usually because I mean if you don't have the right amount of ions in your muscles or outside of your muscles, it's going to cause a cramp because we rely on those ions to contract. Now sometimes it could be lack of oxygen.
There's other things that can cause it, but a lot of times it's just an ion concentration. Okay, so get those clickers ready. Okay, so you're going to have five letters in a row once I get it started and you're going to have to click send. afterwards.
So you're going to have five letters in a row and click send afterwards. Okay. So once you put what you think it is in the first, whatever you think the first is, you go over one.
Nope. Over. Just over for this one.
I see them. My little Russian stacking dolls. Yes. No, send it up to all five are in. Okay, missing two people.
You should have five letters in a row before you click send. I'm just going to give you a few more seconds. Okay, what is the largest? Skeletal muscles are made up of, okay? Fascials are made up of, muscle cells are made up of, myofibrils are made up of, okay?
Okay, so be really, really careful when you answer this. Make sure you look at the diagram. So this is actually pointing to something inside of this that's pulled out of the muscle. This one right here. That's the circle.
Okay, missing three people. Missing one. Okay.
So when we look at this, this right here is what? The muscle. Muscles are made up of smaller units called, so this is one fascicle just enlarged right here.
What are fascicles made up of? So the answer is the muscle cells. Okay. Okay. Now this is one of the first pictures you have on your packet.
You don't have to write on it. It's just for health for later on. Okay. This is a very big muscle cell.
It's one muscle cell in large. I want y'all to notice that it says it's also a muscle fiber. Muscle cell and muscle fiber mean the same thing. I prefer using the term cell because y'all also have the word myofibrils.
Protein fibers. It gets a little confusing with all the F words. So I like to use the term muscle cell. Now, what do we know muscle cells have lots of? They fuse when they're young and then they have lots of them in there.
So if you just look in the picture, all these little purple guys, those are nuclei. I don't really care that you'll know that, but there's lots of them. Sorry, that's my, why do I have a snooze going on at 845?
I do not know. I wish I was still sleeping. Okay.
Now, We also know that muscles'main job is to move, to do work. That means there's lots of energy. What organelle produces most of your body's energy? Do y'all see a lot of mitochondria in that picture? Okay.
In general, every muscle cell, smooth, skeletal, cardiac, have tons of mitochondria. A few, some types, y'all heard of white meat, dark meat? In our body, we have white meat and dark meat. A lot of that depends on how many mitochondria are present. So we'll get to that at the end of the chapter.
Okay. Now, what do we know? I call them straws.
This is one big muscle cell. What do we know we call these big straws that make up muscle cells? Myofibrils. So that is lots of myofibrils in here. They kind of look like straws to me, so that's what I call them.
So muscle cells are made up of myofibrils. So in this picture, we'll see that they're pulling out. one myofibril was showing you the inside of it, which we're going to learn all about the insides of them too, because that's where all the action is happening.
Now, muscle cells are just like every other cell in your body. They're going to have organelles. They're going to have liquid inside.
They're going to have a cell membrane. Cell membranes are not called cell membranes in muscle cells. They are called sarcolemmas.
Let me move this so you can see that word. So in a muscle cell, the membrane is known as a sarcolemma. The muscle cell membrane.
It is the same thing as a cell membrane, it's just known by a different name. Now, sarcolemmas have your typical cell membrane duties. They let things in and out. They hold everything together. But for our particular interest, the circa lemma is going to help conduct action potentials.
Helps conduct action potentials. An action potential is just an electrical signal. It does this very similar job.
They're made out of something different, but... So the Sarko lemma helps conduct the action potential. Now instead of y'all having to write action potentials a hundred times, I will refer to them as APs. And action potentials are just a fancy term for electrical signals. Okay, now how many of y'all, see I won't get my 80s references.
I need to come up with new ones, but I don't watch enough TV anymore. So there's an 80s cartoon called The Snorkels. Anybody ever heard of Snorkels? I'm going to show y'all The Snorkels before we move on, just because it might give you an idea of why I see this. Okay, you'll see those things coming off the top of their heads.
Oh, yeah, you remember this in my one of the best cartoons ever. The little things that live under the sea and they breathe through that little thing off of their head. Okay, so these are the little snorkels. Okay, now let me go back to the PowerPoint. Okay, the snorkels remind me of T-tubules.
transverse tubules. The T tubules are going to wrap around each myofibril. The T-tubules will wrap around each myofibril and they will carry the AP deep into the muscle cell.
The T-tubules will wrap around each myofibril and they carry the AP deep into the muscle cell. If you look at a T-tubule, they look like the little snorkel heads okay so here is an end of a t-tubule does that kind of look like the snorkel head i just showed you okay the t-tubules are gonna take the action potential deep into the muscle cell so if we look at this picture the ap is going to travel down the sarcolema The problem is the AP is only going to touch myofibrils on the outside. But you see this one right here, this myofibril is deep in the middle.
Y'all can't see that red on pink. Sorry about that. I'll see this one right here. Okay.
How is that AP going to get from the sarcolemma all the way to affect this myofibril? What can bring it deep into the cell? The T-tubules.
So that AP is going to end up going. down these t-tubules and wrapping around each myofibril so the t-tubules really connect the sarcolemma to each myofibril okay now also wrapped around each myofibril is some mesh work This meshwork is called the sarcoplasmic reticulum. What have y'all learned that sounds just like that?
Sarcolemma, but think about genbio, endoplasmic reticulum, the ER. So instead of calling this the ER, what do you think we're going to call it? The SR. The sarcoplasmic reticulum is a series of membrane channels, or sorry, membrane tubes that wrap around each myofibril. So the SR is a series of membrane tubes that wrap around each myofibril.
They kind of look like a spider web or meshwork. It's all that yellow meshy stuff around each myofibril. Each SR is going to be a series of membrane tubes that wraps around the myofibrils. Their job is to store calcium.
So if they're storing calcium, what do you think they're eventually going to do? They're eventually going to want to release that calcium. Now the only way that they're going to be able to release calcium is if they get excited Okay for them to get excited the only way your body can get excited is through electrical signals What structure carries that electrical signal deep into the muscle cell? T-tubules.
Okay, so in this picture the t-tubules are these blue tubes the t-tubule t-tubule Okay, and in this picture, we're seeing that the SR is all of this stuff right here. Okay, notice the T-tubules go right over the SR. So there's going to be another part, the ends of the SR, that directly contact the T-tubules. The ends of the SR are known as terminal cisterns.
The ends of the SR... I have no idea what my alarm is set right now. The ends of the SR are known as terminal cisterns.
What does terminal mean to us? It means the end. So this is just a fancy word to tell us that it's just the end of the SR. It's still the SR. It's just the end of it.
Terminal cisterns. The terminal cisterns actually communicate with the t-tubules. They're touching each other.
So the ends of the SR, known as terminal cisterns, are what touches the T-tubules. Okay, so in this picture that I have up here, it's just very enlarged. Okay, this right here, this is the SR. Okay, these are the ends of the SR. What do we call the ends?
Okay, they're still just the SR, but it's just the fancy name for the ends of it. Okay, do you see this tube right here that's going down? What is that tube?
That's your t-tubule. The t-tubule is communicating with what part of the SR? the ends and what do we call those ends terminal cisterns so again anatomy is just as important if you don't know your anatomy is it going to be hard to understand physiology and that's why i spend so much time on anatomy before we touch the physiology okay so the sr is just the meshwork what is the sr storing okay eventually we know it's going to want to release that calcium Now, what part of the SR communicates with the T-tubules?
Which is just a fancy word to tell us that those are the ends of the SR. Okay. Now, we can't just magically release calcium. We have to have something to let it go through. So, on the terminal cisterns, so this picture is an abstract picture.
do y'all see these boxes right here okay these boxes are your terminal cisterns okay still just the sr there's the ends of the sr okay do y'all see these dips right here that's how we get deep into the muscle cell what are those representing p tubules That's not what I wanted. Why are you not? Okay.
Now on the terminal cisterns, we are going to have what we call calcium voltage gates. I call calcium voltage gates VGs. When you hear that term voltage, what do you think about?
Electricity. What's an action potential? Electricity.
The T-tubules carry an action potential down them. What do the T-tubules communicate with? What part of the SR?
the terminal cisterns when the ap comes down the t-tubule it communicates with the terminal cisterns which have voltage gates voltage gates open to electricity when these voltage gates open they're calcium voltage gates what do you think is going to move through them calcium so there's a lot of gates in your body different things open gates This particular type of gate, voltage gate, what's opening the voltage gate? Not calcium. That's what's going through it.
The action potential, the signal, the electrical signal opens it. So I'm going to change pictures just to show you. This is showing us just the structure.
Y'all see this red line now? That red line is what? What is it showing us this red line is? Okay, and action potentials are just what type of signals.
That electrical signal goes down the T-tubules, and it causes what gates to open? Calcium, voltage gates. When those voltage gates open, what's going to exit? Calcium.
Okay, so even though we're just doing anatomy, y'all are also getting about a fourth of the physiology as we go. So let's look at this picture again. Okay, what is traveling down your sarcolemma in action potential?
Let me pick a color that y'all can see, maybe green. Okay, so down the sarcolemma is your AP. How does that AP get deep into the muscle cell?
You got it, through these T-tubules. So AP comes down the sarcolemma, AP goes down the T-tubules. The T-tubules are going to overlap with the terminal cisterns. So AP comes down the sarcolemma, down into the T-tubules.
The T-tubules are going to communicate with terminal cisterns. Terminal cisterns are just a fancy term for the end of what? Not the end of T-tubules, though, the end of the SR.
Okay? So the terminal cisterns are just the end of the SR. What does the SR store? Calcium. When that AP goes past the T-tubules, what gates open in response to electricity?
Okay. Now, when the calcium voltage gates open, what's going to exit calcium? Okay, so that's a big chunk of the physiology is knowing the steps, but you can't understand the steps when you don't see the structures.
Yes. So for any of this to happen. we have to have an electrical signal from a neuron, which we have not talked about.
So that neuron excites the muscle cell. These steps occur. Your muscle cell stores calcium in the SR. It's constantly putting calcium in the SR. When we want to contract, the calcium has to be released.
So it's constant. Anytime we have calcium released, your muscle cell is automatically still putting it back. but we're still releasing it so it's still putting it back so it's constant okay now surrounding everything in here we're going to have a liquid what do we call liquids of most cells not just plasma but cytoplasm okay in muscle cells we have cytoplasm but we don't call it it in muscle cells we call it sarcoplasm Sarcoplasm is the liquid of the muscle cell. So it's going to be the liquid surrounding all of those structures in there.
You can't really see it, but it's there. So it's all those structures are surrounded by the liquid. What makes sarcoplasm a little different from the rest. your body's liquid. What makes sarcoplasm a little different from the rest of your body's liquid is there's more mitochondria.
There's a structure called myoglobin. and there are molecules called glycogen. So the cytoplasm in muscle cells known as sarcoplasm, so the liquid of muscle cells, is a little bit different because it has more mitochondria, it has myoglobin, and it has glycogen.
What does myoglobin sound like? hemoglobin okay what does hemoglobin carry in your body we need it to live oxygen okay hemoglobin is carrying your blood's oxygen myoglobin is carrying your muscles oxygen so myoglobin just carries oxygen in muscles So we have mitochondria, we have an oxygen carrying molecule, and we have glycogen. Glycogen is glucose chained together.
So glucose is a monomer. Glycogen is lots of glucoses. What do we call lots of linked glucoses? A polymer.
So it's just a big, lots of glucose linked together. Okay, now I want you all to think back to GenBio. What do we need? Oxygen. glucose and mitochondria for?
Cell respiration. Cell respiration makes ATP. What do muscles use a lot of?
ATP. They use a lot of energy. Your muscles have to contract.
Contraction is work. Work needs energy. We make energy through cell respiration.
These structures have to be present to make lots of energy. So that is why sarcoplasm is more special than regular liquid. More mitochondria, myoglobin, and lots of glucose.
These three components are necessary for aerobic. And what does aerobic tell us? Air. What kind of air?
What part of air? Oxygen. Okay, so aerobic cell respiration. If we didn't have myoglobin, if we didn't have lots of glucose, If we didn't have lots of mitochondria, we wouldn't be making a lot of energy, which means muscles won't be moving for you. Okay, so let's go back to this picture.
Okay, the AP, the action potential, aka electrical signal, is coming down what part of the entire muscle? What's the membrane called? sarcolemma. So the AP comes down the sarcolemma. How does the AP get deep into the muscle cell?
Transverse, but you can call them T, makes it a little easier, T tubules. Those T tubules are wrapping around the myofibril. They overlap what part of the SR?
The terminal cisterns. What special gate? the terminal cisterns have. Okay. Voltage gates open to what type of signal?
Electrical, which is an AP. So this AP comes down the sarcolemma through the T-tubules. The T-tubules are overlapping your SR. We excite the SR. When the SR gets excited, what gates are opening?
Calcium voltage gates. When they open, what's going to... exit the SR and it's going to leave the SR and go to the liquid of the muscle cell. What is the liquid called? Sarcoplasm.
Okay. Turn to somebody and talk about those steps. Sarcolemma, T-tubules, the SR, the voltage gates.
This is about a fourth of a muscle contraction. So you get in the anatomy, you're good in the physiology. mm-hmm yeah so it's actually that's where it's traveling down so it's like insulation so it's traveling on the sarcolemma but the sarcolemma is only on the outside so how do we get to stuff on the inside okay so it's just carrying this action potential the t-tubules are communicating with that's exactly it which have these on them which open yep because of the action potential and it releases calcium into the center. You got it.
It starts on the sarcolemma. So it's basically just conducting the AP, but we need it to get into the middle of the cell and that's where the t-tubules carry it. The t-tubules are made out of the same stuff as the sarcolemma, they just go into the cell. They're just basically tubes, they're part of the sarcolemma that just invaginates in. That's the word they use in the book, invaginates in.
okay no uh-huh no no it's just yeah it has the top made our conjurer conjurer means different things it means cartilage but think about a hypochondriac it has nothing to do with cartilage yeah yeah so yeah no but there are some some medical terms like Latin and Greek roots, they can't have multiple meanings, which makes it even more confusing. So we have to know the reference that we're using it in. Yeah. Leave it to A&P to confuse us. Okay.
So here are, let me just, sorry, real quick, let me get these started. Here is a question. Read them very slowly and carefully. It's saying what structure causes calcium to be released from the cisterns. Terminal cisterns are the end of what?
The end of the SR. So what structure is causing that to be released? So what's communicating with the terminal cisterns?
you're missing two people missing one okay so i don't have every single structure on here i have a is pointing to what what's all the yellow mesh work okay b is pointing to soccer lemma what is c pointing to and then d is pointing to So out of those four, what's causing the terminal cisterns to release the T-tubules? Okay, here's another one. Okay, I'm missing three people. Okay, out of these four, which one is actually storing the calcium?
The SR. Okay, so that's going to be letter, you got it. Don't worry, okay, we didn't go over that, so we won't do that one.
Okay. Here's another one. Okay, great job.
Everyone got it right. What is it? Yeah, so even though I have a lot of fluff in this question, it's saying what binds oxygen.
The only one that binds oxygen is myoglobin. Okay, so this is a lot of information. We're going to keep adding to this, which means next Thursday, because test is Tuesday, I'm going to jump right back where we started.
So look how empty the classroom is. I need y'all to email y'all's peers and tell them they better watch this video because this is the most important test. It's everything for A&P 2 and I can't give another class period to reviewing this again, okay?
This is also what y'all are doing in lab. Y'all are finishing up bones and starting the muscles. This is your physiology for your lab tests.
It is primarily going to be on muscles. There's not too much on the axial skeletal system that you do in physiology. So This is super important.
It's supporting your lab. You need it for lecture. It's not on your test, but apparently students don't listen and come to class to me. So I need y'all to convince them to come prepared next Thursday, because I'm going to see a lot of blank stares when I go over this on Thursday. Okay.
Good luck. If y'all need anything, email me over the weekend. I have lots of tools to help support you in studying. Oh yeah, yes, yes. You were like, I was like, what are you talking about?
Hold on one second. Let me just stop this recording.