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BIOL 3324 Human Physiology - BIOL3324_lecture12_1003
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00:02 Right. So on days like this is fun when you walk across
00:06 because you can actually see how sad are about the life choices they've
00:11 They're usually walking around without umbrellas. What we're gonna do today is we're
00:16 talk about how muscles work. Um many of you guys have ever learned
00:21 muscles? Any class? Biology? , right? So good. All
00:26 . So, uh here's the good y'all, there is like one slide
00:30 here like midway through. That's let's put it all together. And
00:35 truth is is we're gonna spend probably minutes, 50 minutes talking about all
00:39 steps. But ultimately, if you to that one slide, it has
00:42 the steps, it basically boils everything . And so it's a real easy
00:47 to do that. This is one those pathways where it's let's build the
00:50 trap. OK? And again, I refer to that, that's the
00:54 the mouse trap where you put the Goldberg machine in play. All
00:58 So that's kind of what we're looking and really what we have here is
01:03 going to be looking down at the level of a muscle to look and
01:07 how a muscle actually works. We're going to be looking at every muscle
01:10 the body. We, we might a little bit of an overview of
01:14 a muscle contracts, but really, down to the level of the individual
01:18 . So we've got to move ourselves to that to that individual unit in
01:22 to understand that. But just so you have this kind of this big
01:25 of what we're going on. Skeletal are organized into groups of cells that
01:31 , are working together to cause a in a particular direction. In other
01:36 , to move a bone or a in a particular direction. So you
01:41 , I think over 600 named muscles your body, that's not something you
01:46 write down. It's just something you to know that at some point in
01:49 future, you may have to memorize all. All right, it's just
01:53 of the way it goes. Um in order to get that named
01:57 so like what's this muscle called? should all know this one bicep.
02:02 , that's the bicep, right? that bicep is actually a bunch of
02:07 in of, of, of, packaged groups. So it's a group
02:11 packaged groups of cells that are there do the job. And so you
02:15 see here that what we're doing is coming down to the individual cells.
02:19 this is the individual cell right This is called the myofibril. You
02:23 a bunch of those and you wrap up in connective tissue. What you
02:26 is a all right. Actually, sorry, this is the, I'm
02:31 . This is the mile fiber. fibro, my fibro is not the
02:35 , mild fiber is the cell. these are the individual cells, you
02:38 them up together in a fale and that's wrapped in connective tissue. So
02:42 have groups of cells working together and you take a bunch of fales and
02:46 them up. So it's kind of what we saw with the nerves,
02:49 ? The individual nerve is wrapped by tissue. Then you take a bunch
02:52 them and wrap them together and then bunch more and wrap them together.
02:55 that's kind of when you think of a, that's really what it
02:57 It's groups of fales. And if is not something that you can kind
03:01 perceive or, or uh understand right , my I encourage you to go
03:05 a grocery store, wander over into butcher department. Look at a piece
03:09 meat, particularly a piece of pick it up and look at it
03:12 it's basically a cut through or a section through a muscle and you'll actually
03:16 the individual fast uh in that meat then buy the meat. Eat
03:21 be happy. OK. Now we names for the concentric layers. So
03:26 we had um um the specific terms the uh connective tissue of the,
03:34 the um uh we have the same for muscles. So, Endomysium or
03:40 is going to be the one that's around each individual fiber. Again,
03:44 purpose here of that connective tissue is separate it electrically from all the other
03:48 so that they do not touch and not sending electrical impulses between them.
03:53 each individual cell is going to have own uh neuron that's going to innervate
03:58 . And then you take a bunch those, wrap them up with
04:02 That's how you get the facile, a bunch of fast, wrap them
04:05 with more connective tissue. That would the. Now, the way that
04:09 muscle works, generally speaking is that muscle uh has a body that's kind
04:14 a fat portion of it. So think of the, the belly of
04:18 muscle is what it is. and then that uh muscle, that
04:22 tissue that's around each of the individual , around each of the individual fast
04:26 then ultimately around the whole muscle come and they join up to create kind
04:31 this this thicker cord of connective And that is your tendon and it's
04:37 tendon that the muscles attached to. when a muscle contracts, what it's
04:42 doing is it's pulling on the connective , the connective tissue then pulls on
04:47 bone which causes the movement of that . And depending upon how much force
04:52 needed, you're going to recruit different of fales or different groups of
04:57 These are going to be called motor . And we're going to talk about
04:59 units a little bit later. But other thing is that when you
05:02 we kind of talked about the stretch the tendon, right. When you
05:06 on that, that tendon is going stretch a little bit, especially if
05:09 greater resistance. And so really what doing is you're pulling first on the
05:13 and it's the tendon that's doing the pulling if that kind of paints it
05:20 . Now, Mussels themselves also have around them if you've ever gone
05:23 And you've, uh, I see I just, I just went right
05:25 Texas, right. Went hunting, hunting and then you go skin
05:29 that critter. Right? All Let's, I presume many of you
05:35 gone hunting. But if you go the grocery store and you buy,
05:39 a, a full fryer, that be a chicken, you'll notice that
05:43 , they've plucked it and it has layer of skin and you can actually
05:48 that if you remove that skin, see how the muscle itself is completely
05:53 in a connective tissue that we refer as fascia. And there's also,
05:57 deep fas as well as superficial not so important for our class.
06:01 I understand that organization of muscles is result of the connective tissue that binds
06:07 muscles together. So for your upper , for example, to create this
06:11 , there are three muscles involved, ? The bicep is the primary
06:15 but each of those individual name muscles their own stuff and then those things
06:19 bundled together and that would be the . So what I want to get
06:24 though is I want to get down the individual cell, right? Individual
06:28 where all the actions happening, this what we call the functional unit,
06:32 ? And really truly the functional unit a muscle cell. And remember muscle
06:37 are as long as the muscle are . So for my bicep right,
06:41 have um an origin up here and have an assertion down here. So
06:46 disregarding the tendon for a moment, length of that the cells in the
06:50 are going to be the length of muscle. All right. Now,
06:56 like in the nervous system, the who were first uh exploring the muscle
07:01 that all the pieces, parts were . So they gave them all special
07:04 even though they're the exact same stuff find in other cells. So the
07:08 membrane is not called a plasma it's called a sarcolemma. Thank you
07:12 making me memorize another word, We have the sarcoplasm, which is
07:17 cytoplasm. All right. We have sarcomere, which is the functional unit
07:22 we're gonna define here in just a . But I want to point out
07:25 couple of things. All right. Way back in biology, one you
07:29 , oh, I put glucose in body with a little bit of oxygen
07:32 makes the body go all right. what they kind of don't describe is
07:36 we actually store up glucose in places than the one place that they taught
07:41 , which was the liver, Glycogen gets stored in the liver.
07:46 great. Well, muscle stores up as well. Form stores it up
07:51 glycogen and this would make a lot sense, right? And it also
07:56 up oxygen instead of just waiting for to breathe it in again. I
08:00 you to paint the picture here. walking along the street. Shasta jumps
08:04 , not the cute little cuddly but the one that escaped from the
08:07 with his twin brother. And they're haunting students, hunting students,
08:12 hunting, let's say hunting students, ? He jumps out of the bushes
08:16 at you. Do you want to for your respiratory system and your muscles
08:20 decide it's time to run or are just going to run or fight or
08:23 or whatever it is that your sympathetic wants to do? What are you
08:26 to do? Do you wanna do wanna wait or do you wanna just
08:30 , you want to get OK. . So by having a way to
08:34 up oxygen in the form of myoglobin is the binding molecule here,
08:39 like hemoglobin is in the blood. learned about. He, you've heard
08:42 it. We haven't talked about it , but hemoglobin binds up oxygen carries
08:46 in the blood. Myoglobin is related hemoglobin. It binds up oxygen and
08:50 , it allows you to keep it . But again, you also have
08:53 OMs, this is just Glycogen. I have free access to fuel.
08:57 that when I need that energy I just start breaking down glucose
09:00 I don't have to wait for them be delivered when my liver decides to
09:04 catch up with my body. What do I have here? Oh High
09:09 mitochondria. Why would I need lots mitochondria? What mitochondria do? A
09:15 ? Right. So this is going be an energy producing cell. They're
09:19 a lot of energy. We'll see in just a moment. Lastly
09:22 it's multinucleate and this is something that don't see a lot of. And
09:27 reason for this is developmental, your and your fat cells originate from the
09:34 precursor. There's actually like one gene turns on that decides that this cell
09:38 going to go that way or that . Some days it feels like you
09:42 they all went one way to But it, that's not how it
09:45 . It's developmental. All right. what happens with muscle is that they
09:52 merging muscle cells, these little myocyte myoblast, they merge with each other
09:56 form skeletal muscles. And so this why you get these really, really
10:00 cells, right? So when you at a muscle fiber, that
10:06 it's a single cell now, but one point, it was mini cells
10:10 that makes sense. OK, it all those nuclei. So that's why
10:16 multi nucleated. All right. um We're gonna go into more detail
10:22 , but it is a defined uh within the structure of a skeletal
10:28 Uh There's gonna be a structure here we're gonna look at, it's called
10:30 Z disk. So basically, what do is you have the Z discs
10:33 the boundaries and the space in between that functional unit. And what we're
10:38 to do is we're going to see there are cyto skeletal elements within
10:41 within these two Z discs that are . And what we're going to do
10:46 create a contraction is we're going to on these cyto skeletal elements to bring
10:51 two Z diss closer together in the of a contraction. Now, if
10:55 think of an individual cell, which like this long and you're talking about
11:00 as being microscopic, you can imagine cell has hundreds, if not thousands
11:05 sarcomere. So, a contraction is group of contractions within the context of
11:12 individual sarcomere. So, thousands of within that structure does that kind of
11:17 sense? Now, right now, you don't know what the sarcomere
11:20 that's OK, we're gonna come back we're gonna look at it more
11:24 Some other structures that are absolutely necessary you to understand are going to be
11:29 uh uh these organelles that are found inside the muscle. We have the
11:35 tubule referred to as a T So here, what you can imagine
11:39 the surface of the cell, you a tube that opens up and then
11:42 travels through the cell and opens up the other side like a tunnel.
11:47 . That is the transverse tubule. what it does, it brings the
11:51 of the plasm membrane inward towards the of the cell near to the structures
11:57 that cell. That's its purpose sitting budding right next to the transverse tubule
12:03 the end part of the uh muscle . Here. What we've done is
12:08 modified it. This is now this what we, what we call the
12:12 partic and it's been modified to form is called the sarcoplasm partum, you
12:18 , so you can once again see have we done. We just added
12:21 s at the front and called it . Now, here you can see
12:25 here, it's these yellow s switched pieces and you can see it
12:28 but right up next to each of transverse tubules, the end of the
12:33 partum nearest the transverse tubule bulges out creates a little tiny cistern, a
12:38 tiny aula. And so we call the terminal cni. So it is
12:43 of the sarcoplasm cic, but it's from it, all right, just
12:48 it's broader and it plays kind of important role in what the cell is
12:53 . So collectively, these structures, T tubule, the terminal cern and
12:58 sarcoplasm partic collectively are referred to as triad. We're not gonna talk about
13:03 , but I'm just gonna say it at some future point, you're gonna
13:05 this, not in our class, some place else when you go into
13:08 heart, the heart doesn't have a . It has a dia so it's
13:14 same, but it's not OK. , what we're gonna do here is
13:18 gonna walk through and get ourselves to T tubule. All right. So
13:23 steps that we're looking at here are happens at the motor in what happens
13:29 we stimulate a muscle cell. And what we're looking at here is the
13:34 junction. So here it is the next to the, the muscle,
13:37 can see the neuromuscular junction is this is the motor implant underneath
13:41 That would be the synaptic cleft. it actually potential travels comes down to
13:45 synaptic knob causes the release of a really calcium into that synaptic or into
13:51 synaptic knob which causes the vegetables to up to release their neurotransmitter. The
13:57 in a muscle or a neuromuscular junction always, always, always, no
14:02 to the rule. The only time ever hear me say this is acetic
14:06 . Ok. That I see the travel across. Have I taught you
14:12 new yet in this or does this all very familiar? I'm I'm,
14:16 should be going. Yeah, we learned this when we talk about neurons
14:19 is the downstream cell. It's not neuron, it's a muscle. So
14:24 see the co travels across the synaptic binds to a receptor, that receptor
14:29 up. It's a channel allows sodium the cell. Sodium floods into the
14:33 . It creates an action potential. , truly, what it's doing is
14:37 uh producing a graded potential called an potential because we're at the motor in
14:45 . So an Epp now the in potential is really powerful. It's so
14:50 that it causes an action potential. you don't have to do anything
14:54 you know, there's no summation It's just you're gonna get your action
14:59 . And so what happens is that potential as a result of the binding
15:03 , it basically gets formed and cross starts moving across the surface of the
15:09 . All right. Great. That's hard. So basically, I produced
15:12 action potential. So I have an potential here in the neuron through the
15:16 synaptic processing that I normally do released chemical message that resulted in producing an
15:21 potential in my muscle cell. So far, so good, nothing
15:25 . What happens is now that action going to travel along the surface of
15:29 cell and it's gonna come across every I see the T tubule that a
15:34 is then gonna travel down through those tubules and it's still gonna go across
15:38 surface of the cell. But the got lazy and didn't show us
15:41 All right. So we can see what we're doing is we're going down
15:45 those T tubules which is still cell and we are now gonna be activating
15:50 unique channels that are located within the two field. So here we
15:56 again, we're showing you up close going on here in the T
16:01 All right. Now, there are different types of receptors. Here,
16:06 have DH P receptors which are located the T tubule and then associated with
16:10 terminal C systems are what are called receptors. They're closely related to each
16:16 . You can think of them as bumping. All right, they're actually
16:19 with each other through a small And what happens is is when I
16:24 the VHP receptor, which is a gated channel, that voltage gated channel
16:30 up and it causes a change in shape of the iodine receptor. And
16:34 the iodine receptor opens up and it's basically a channel that allows for the
16:40 of calcium out of the terminal. , the purpose of the sarcoplasm partic
16:46 terminal cy is to sequester weight to on to calcium until an action potential
16:53 and shows up. All right. the first thing you should walk away
16:58 here is that calcium is really important the cell, right? Calcium is
17:04 of the major signaling molecules in a cell. All right. So could
17:11 walk through those steps? Do you you could do that pretty easily?
17:15 action, potential release, chemical What's the chemical message? See
17:20 see, the coline binds a receptor a potential travel along the goes down
17:26 T tubule. T tubule acts activates P receptor DH P associated with the
17:31 ir I receptor opens up a release . See, it's not hard.
17:38 year, I know you love my . One year I was teaching this
17:42 my laptop died and I didn't have chord. It was a terrible
17:45 I had to do this whole talk the chalkboard which is will get you
17:52 focused really quickly on. Oh I've got to just walk you through
17:55 the steps. But because there's just , it's ABC DE, it's not
18:00 to memorize. You just have to what step leads to the next
18:03 OK. Now we're gonna put our on pause. So calcium is being
18:11 and now we're gonna go inside the . I'm gonna look at this
18:14 All right. Now, at some , you probably had to memorize
18:18 whether it was in high school or it was in a bio one where
18:22 had to look at a muscle. you said here's a soft, here's
18:24 Z line and I've got all these and thin filaments. Have you guys
18:28 have to do that? Wasn't it nightmare? You're like, I'm not
18:31 if I really understand this. what you're looking at here is what
18:35 scientists first saw when they first look a microscope at a muscle cell,
18:40 saw a bunch of stripes and so basically named the stripes based on how
18:45 they are. And so we ended with a couple of different bands.
18:50 don't even remember what the letters stand at this point now. But basically
18:53 you can say is all right. they, they decided that the two
18:57 lines. So here's your Z Z line, the Z lines are
19:00 ones that are surrounded by this light . And so they said, all
19:03 , well, on either side of Z line, we're gonna call that
19:06 I band collectively. So really if look at a scam, if this
19:11 the whole scam, you start off half an eye band and you're gonna
19:14 with half an IAND. All you need a starting point someplace.
19:18 as well just pick that. That's they did. All right. So
19:23 have that and then we said, , the dark line begins here and
19:27 stuff happens, but the dark line kind of continues for away. And
19:30 we're going to call that the A . So I have a light band
19:33 I have a really dark band and the light band again appears. And
19:36 I got my two Z diss. half an I and then I have
19:40 A and then the A band actually some light stuff on the inside.
19:44 he said, look, it's a bit lighter. So where the light
19:47 and where the light ends, we're call that the H band and then
19:50 the middle, we have this dark in the center, we're gonna call
19:52 the M line or the M All right. So, really what
19:56 have, you have these different structures are, that are found within the
20:02 of these bands. And as we better at the science, we were
20:05 to discover what they were and what determined was is that here in the
20:10 band, what you have is you a bunch of thin filaments. We'll
20:14 about that in just a moment. right, where it's really, really
20:20 dark is you have an overlapping of thin and thick filaments. OK?
20:26 then here in the middle where it's dark but not as dark as over
20:31 , you're gonna have just thick So the way you can look at
20:34 go, here's thin, here's thick thin, there's thick. Then I
20:38 this weird band on the center and it's thick, thick and thin and
20:43 . Now, the way you can at this, can I borrow your
20:46 again? So his arm represents, he's a Z line. So this
20:51 be a filament that originates at the line and moves out. Can you
20:55 see over there? Well, I'll it on that side too. All
21:00 . But here, I'm the I the in line or the in band
21:04 then I have a thick filament that for me and then together where our
21:10 overlap, what do we have? , thick and thin? So,
21:15 you'd say is Z I, here the beginning of the A and then
21:20 is the H and then I'm the and then ran and repeat on the
21:23 side. Thank you very much. that, is that helpful to visualize
21:28 ? Can we do it on this ? So you can see a little
21:30 better. So he is a Z . This is a thin filament on
21:38 M band or the M line. this would be a where we overlap
21:44 would be here to all the way the other side. That would be
21:49 A band. OK. So what have here, thank you so
21:53 So, what we have here is a, a visualization of what's in
21:58 sarcomere and we're defining it based on thick thin filament. Now, there's
22:04 within the sarcomere that are kind of , we're just gonna mention them and
22:09 we're gonna kind of ignore them from on. All right. But the
22:12 molecule I want to point out here uh Titan and the Titan here is
22:16 Titan. Titan would be with an at the end. So Titan is
22:20 little tiny springlike blue things that you're in our little cartoon. If you're
22:26 , what do you expect to happen them? You can stretch them and
22:29 when I stretch them, they compress if I compress them, they spring
22:34 out. OK. And that's exactly purpose. All right. So what's
22:40 is, is that I extend from Z line to the uh the molecule
22:46 makes up the M line. So , it just goes all the way
22:48 the center of those thick filaments. so what happens is is when I
22:53 when I create a contraction in the , the two Z lines come
22:57 So the spring compresses and then when relax the muscle, I don't have
23:03 do any work, right? Because relaxation And so what happens is the
23:08 pushes the disease back up to the position, kind of important,
23:13 That means for every time I contract the muscle relaxes, it passively returns
23:18 its original shape. Second um molecule is a molecule called nebule nebule sits
23:26 the middle of the thin uh of thin filament. So it's not really
23:29 easy thing to see here. They're kind of pointing saying there it
23:32 But you can imagine what it It's a very stiff molecule and it
23:35 straight out like this. And then thin filament is associated with. So
23:39 the thin filament doesn't go down, doesn't go up, it doesn't go
23:42 . And so what that does is ensures its position in the context of
23:46 thick filaments. If you look down at the bottom, those hexagons that
23:51 looking at is basically taking that cross of the score and turning it so
23:56 you're looking along its longitudinal length. so you can see here, the
24:00 green dots represent thin filaments. The orange dots look are represent thick
24:06 And you can see that they're arranged such a way that each thick filament
24:11 six thin filaments wrapped around, So if those thin filaments get all
24:16 , they can't have an interaction with thick filament and the contraction is dependent
24:23 the interaction of the thick and thin . So, ambulances job is to
24:28 that the thin filament sticks out and exactly where it's supposed to go.
24:33 we have another molecule alpha and that's basically the molecule that catches the thin
24:38 to the proteins of the Z So when you look at these pictures
24:43 the M line of the Z what you're doing is you're looking at
24:46 , a network of proteins from this . And so it looks like a
24:50 . But if you turned it this , you'd see that it was a
24:52 work of proteins that are basically holding together. So it's kind of like
24:56 lattice. And then what you're doing you're sticking out a whole bunch of
25:00 with thin filaments that are pointing out you. And the M line is
25:03 of the same way, there's a of proteins in there that create this
25:07 so that they're arranged in this particular . So these Sarcos and these
25:21 these mild fibers are arranged in such thick way that they take up almost
25:28 entire cytoplasm of the cell. I'm go back a couple of slides
25:34 Just I want you to see the . All right, this, this
25:38 fine, you can pick any of . So you can see here here
25:41 the plasma memory and that's the And each of these represent bundles of
25:47 thick and thin films. Those are myo fibrils and in their relationship to
25:52 other. So, I mean, there a lot of space in there
25:57 they're filling up thing if we uh we need to go like
26:00 I mean, but you can go , you see what they're trying to
26:02 you is that this thing is just but cytoplasmic uh or sorry, a
26:09 of, of, of filaments filling that space. And this is why
26:15 muscle cell can do the contraction because is simply just a bunch of micro
26:20 tied to both ends of the cell be able to contract these things
26:26 Yeah, thank you. Yeah, don't wanna just hear the thing banging
26:33 the side of my leg. All now, thin filaments and thick filaments
26:44 more than just the name. All . And their parts are important because
26:50 shows you how they work together. the thin filament consists of three parts
26:55 have act in. That's probably the you're most familiar with. Acton is
26:58 molecule that interacts with another molecule called , which is going to be what
27:02 find in the thick filament. All , it's basically a bunch of strands
27:06 these smaller molecules. So act and can see here is uh is this
27:11 . So it's the purple, not purple, lavender. Is that the
27:16 colors there? Is that blue or ? All right, we're gonna call
27:20 blue and lavender and then the yellow and the mustard because there's a darker
27:25 in there. If you see can you see the color? I'm
27:28 guy. I just see two All right. But it's that
27:32 And you can see we have an helix and each of each of those
27:37 structures is an acting molecule. So see we got these long strands,
27:41 long chains of acting that creates this and on each of those little tiny
27:47 bundles, each of these acting molecules the binding site for my. So
27:53 one of them can bin a All right. The problem is we
27:57 want it to bind to my. it binds to my, it will
28:00 it and it will be like yes then your muscle doesn't move. So
28:04 want to get in its way. so we have a molecule that gets
28:07 the way and prevents it from binding and we call this of my,
28:12 related and it has a small affinity that sin binding site, but not
28:16 very strong one. So this um little tiny rope, as you can
28:22 , it is running along the surface wrapping itself around like so that's troy
28:27 it's basically sitting over the mycin head the binding site. You can think
28:33 it like this. If my hand acting, it basically sits like this
28:36 says, nope, you can't get there. So it prevents my from
28:40 . The problem is is if it's the way of mycin binding, I
28:43 want my to be able to bind under certain circumstances. So I need
28:47 get it out of the way. we have a third molecule that has
28:50 parts. It's called troponin. Troponin like a hinge molecule. It's bound
28:55 to the act and it's also bound to the Tropomyosin and it has three
29:00 , one that's bound up to the one that's bound up to the act
29:03 it has a catalytic component. All , this is the TNC that's being
29:08 listed up there. The TNC binds calcium. You remember what I
29:14 calcium is important when calcium binds to , what it does is it changes
29:19 shape of troponin. So it goes a position like this to a position
29:24 like that. And because it's bound to the troy, when it changes
29:28 , it pulls troy out of the . So now that triple or that
29:32 binding site on acting is freely available bind my, if it happens to
29:38 around. OK. So three parts the thin act, that's your
29:45 trip, trip, that's your chaperone your, your regulator. And then
29:50 , which is the thing that does the hard work because it's dependent upon
29:55 . Yeah, I was it. . Right. So there's an F
30:05 and then there's a G Acton and can't remember uh is it the,
30:09 think the F Acton is the G. Acton is the individual?
30:12 can't remember today. Does that sound ? Yes. Thank you for those
30:16 you who read the book, you this? OK. Right. But
30:21 what it is is just saying, , each of the individual ones are
30:23 of interacting so they will bind But the way that acting creates that
30:29 chain is basically just attaching each to little individual subunits. Yeah.
30:35 All right. Thick filaments, a of golf clubs have been wrapped together
30:39 then bundled up, wrapped together. right. So each uh each thick
30:45 is a my molecule. You can here the Myson molecule looks like someone
30:49 a golf club and has wrapped the shaft. So you can see it
30:53 of has this alpha helix to right? And then what happens
30:57 is at the very end, the heads are independent of each other.
31:00 if I could wrap my arms, would, but you can imagine like
31:03 , I have two heads that are of each other like so, all
31:08 . So the long portion. All , right here. That is the
31:14 the tail. What we have up is the globular heads. The globular
31:18 is where all the action is taking . So here at the top of
31:22 head, what we have is we a binding site for acting. So
31:26 is the portion that wants to interact acting, but it can't because Rey
31:29 in the way. All right, other thing that it has, it
31:32 a binding site or not a binding , it has an A TP,
31:35 site. So what it needs, needs a little bit of a TP
31:39 do, do its thing. All . And what it's going to do
31:43 that each individual head acts independently of other and actually works in this particular
31:48 . All right, they don't work like this one works here. One
31:51 over here. So they're going to swapping position. And this kind of
31:55 sense if you can think of acting a rope. If I have,
31:59 I'm using both hands to pull the , if I let go and it's
32:03 to a spring, what's going to to the rope goes right back to
32:05 it started. So, what I to do is I want to do
32:08 hand over hand action. So each these my and molecules are kind of
32:12 a hand over hand pulling on the in. OK. Now, um
32:18 we have is also the M and chain. So this will become more
32:22 a little bit later when we talk smooth muscle. But it's this light
32:26 that uh plays an important role in the hinge portion of the head.
32:32 the way you can think about this that, uh, there's a hinge
32:35 the head and so what it does it moves like, so, so
32:39 not a full, it's just that head portion that's moving. All
32:46 So when you exercise, what do need for? Fuel is not a
32:54 question, what do you need for ? Well, glucose, but take
32:58 TP. That's what I'm shooting So, when you think about
33:02 you always think about a TP. what we've taught you since the dawn
33:05 time. And it is true. muscles need a TP. We have
33:08 A TP A site. But the important factor in order for a muscle
33:13 contract is calcium right now, remember we started at our neuron, sitting
33:23 its a potential oxygens rise at the knob causes the movement of the vesicles
33:28 open up, release your colon. goes out into the uh neuromuscular junction
33:33 an Epp which is a strong, potentially a potential travels along the surface
33:38 the cell goes down to the T binds or it causes the opening up
33:42 the DP receptors which causes the opening the rine receptors on the terminal
33:46 Calcium comes flooding into the cytosol of cell. And where does calcium bind
33:56 ? When calcium binds troponin? What it do? It pulls troy out
34:00 the way, which is what this trying to show you. See,
34:04 is bound, I can now interact bind to acting and when that interaction
34:12 place, that causes the head to and to pull. And so not
34:18 are you grabbing onto the act and pulling on the acting? And that's
34:22 the calcium allows. This is what called the cross bridge. All
34:26 the interaction between acting and my is cross bridge now. Great. But
34:36 were talking about a TP. Why I care about a TP?
34:43 I think you'll like this part when person dies, right? And has
34:51 on the table for a while. is the first thing that happens to
34:55 body rigor mortis? It stiffens up mortis and then after a little bit
35:04 time afterwards, then it relaxes again becomes gooey and gross. OK.
35:11 is rigor mortis? And why are bringing this up in the middle of
35:14 talk about a muscle? Ok. , rigor mortis occurs because of the
35:21 of a TP. Your body has TP and a very small concentrations of
35:27 TP. All right. And what TP does, it allows for the
35:32 stroke to occur. Now, you start anywhere in this circle. All
35:36 . But because the book starts up , first off, that's where we're
35:40 to start. And so what we're to say is we've released calcium into
35:44 cell and calcium has allowed the myo bind up to and pull on the
35:51 . So what do I need to ? What's the next step in,
35:54 order to create a more complete I want to keep pulling on the
36:00 . So how do I pull on rope? I have to separate the
36:06 or the thick filament, right? sin had from the act in.
36:11 so the important part of A TP to create that. So Atp's job
36:17 to separate out the interaction between Acton Myson. All right. And then
36:23 that happens, the A TP activity the M and head happens and that
36:30 the position of the mayas and All right. So our starting point
36:35 here. So it's, it's an the fact we've already gone through our
36:39 . Right. Right. And now we're doing is we're separating out,
36:45 break the A TP and we reposition recock the thick filament the my
36:52 Now, if there's more calcium is interfering in the way or getting in
36:56 way of my and interacting with the , no. So what I'll do
37:01 I'll bind again and when the mycin to the act in, it will
37:07 the head to contract and move the in again. And then what do
37:12 need to do? I need to a TP again, separate it
37:16 Break the A TP, recock and I'm ready to go again. So
37:21 power stroke, this ability to break bond. The interaction between acting and
37:28 is the result of a TP back rigor mortis. You have stores of
37:36 TP in all your cells, not lot, but you have a little
37:40 . You die, your cells are dying but they no longer have the
37:48 to regulate the the uh sequestration of inside the muscle cells. Right.
37:56 the muscles basically start releasing the calcium the sarcoplasm. Calcium. Is
38:02 All right. I move troponin out the way I can start interacting mycin
38:08 acting. I have a TP, can contract, I can contract,
38:11 can contract. I run out of TP. What is the muscle
38:16 It's stuck in a contracted state. rigor mortis kind of cool for
38:25 whichever way you want to look at . This is the part where I
38:28 you about my grandfather working in a . He, he told this
38:31 Is this true? I don't This is, this sounds like your
38:34 story back back um prior to World Two. So it was a long
38:38 ago. He got a job in school being the night watchman is what
38:42 said, being a night watchman in morgue. And he said he was
38:45 through the morgue and they did have cadaver on one of the tables and
38:51 sat up and he said he dropped flashlight and ran out of the building
38:54 he never looked back and why would have sat up rigor mortis?
39:02 I don't know if it's true. . So you know how we get
39:06 contraction, right? So calcium floods when calcium floods in it moves proponent
39:12 of the way actinic can interact. TP is present that allows me to
39:15 the bond or the interaction, reset head so I can keep that contraction
39:20 . But there's going to be a where you're going to relax. So
39:24 I turn anything on, everything that turned on along the way has to
39:27 turned off. And so all I to do is I've got to stop
39:30 that excitatory signal from the neuron. excitatory signals, no eps, no
39:36 no action potentials, no action no stimulation of opening up the DH
39:40 receptors, no DH P receptors, iodine receptors. Calcium is now stuck
39:45 the cytosol, right? No, have pumps, pumps associated with the
39:50 reticulum. These pumps are called circa . Smooth endoplasm reticulum, calcium
39:58 That's where their names come from. yeah, and they're always on,
40:03 never turn them off. But what do is they constantly pump calcium back
40:08 the sarcoplasm reticulum. But if you your iodine channels open, then the
40:14 just keeps flooding back out into the . But if there is no
40:19 calcium gets pumped and moved out of cytosol and gets sequestered away inside the
40:26 reticulum, no, calcium troponin goes to its original position acting my can't
40:36 . Is this feeling a little bit ? I mean, other than memorizing
40:41 weird names that are associated with I mean, do you see how
40:44 A results in a step B, B to C so on and so
40:47 all the way down? This is right here. This is the slide
40:51 I was telling you about. it everything we walk through. There's step
40:55 and step two, a potential going , open up the DH P receptor
40:59 causes the iodine receptor to open up floods out. Then what do we
41:04 cause troponin to move out of the , act in and trip or act
41:07 a and start interacting, right? TP allows me to keep pulling on
41:14 bringing the muscle together. And so ends up happening is that the Z
41:18 will start moving together and you can hundreds of thousands or tens and,
41:23 hundreds and or thousands of Z lines pushed together all along the length of
41:28 muscle. And so this is why length of the muscle gets smaller.
41:32 is what the contraction is. That's a muscle contraction in a
41:40 And that's happening in every single cell undergoing a contraction. I'm gonna pause
41:47 . Are there questions about that? . Yeah. So relaxation is just
41:52 opposite of, of the stimulation, ? So anything that I turned on
41:57 to be turned off. Right. if the key, if the key
42:00 here is calcium, if all I to do is stop causing calcium to
42:05 released, then I can remove the . Right. And so the way
42:11 happens is because nothing, if you off the, the excitatory signal,
42:17 those steps, those early steps will . So right there, I won't
42:22 the calcium, but you need something remove the calcium from the cytosol.
42:26 that's where those circa pumps become important what they're doing is they're constantly moving
42:32 back to the sarcoplasm reticulum. It's that when you open up the iodine
42:37 , you know, more calcium is than is being pumped in. It's
42:40 having a big giant gaping hole in boat. You can have a bilge
42:44 , but you're still going to right? Any other questions about
42:53 So this is, this is the mechanism of a muscle contraction. No
42:59 . OK. This is awesome because gonna be tested on this. Who
43:05 just put the parts together, draw out. If you have to just
43:09 this picture, talk it through with other. Make a song. If
43:15 need to do a dance, I have a dance major once who actually
43:19 write dances for everything that we taught . Now, there are two primary
43:25 of contractions. All right. This where you get to watch me make
43:29 ass out of myself. This feels a heavy enough chair. All
43:42 I have isotonic contractions. I have contractions and isotonic contraction is when the
43:48 is going to get smaller, A contraction is taking place in the
43:52 length. But the amount of force I'm producing doesn't change. All
43:58 So I'm gonna show you a simple contraction and then I'm going to show
44:02 a more advanced one, not more , but much more difficult. I'm
44:05 be using the same set of How much do you think this bad
44:08 weighs two or three ounces? So, let's watch an isotonic
44:15 Check out this bicep. I work every day just so that I can
44:19 this one thing. But did you that? Did the muscle get
44:26 Let, no, you sure? my bone was here and now it's
44:31 . So the muscle here is getting . Do you see that?
44:40 Now, in order for me to that, do I need a lot
44:42 muscle fibers to curl the little pointy ? What do you think?
44:49 All right. Same set of Chair, right? Does the muscles
45:05 smaller? Yes, they use more to do that. What do you
45:12 ? Yes. OK. Now there's movements in there. All right,
45:16 muscle length got shorter. That was easy one to see. All
45:20 So here is the muscle getting shorter I put the chair down, what's
45:24 muscle doing? It's getting longer. we have two types of isotonic
45:30 We have concentric muscle getting shorter, have ey muscles getting longer. So
45:36 I'm putting down the big heavy rather than dropping it on the floor
45:40 hurting myself and the chair, what doing is I'm maintaining a contraction and
45:46 slowly releasing it, but I'm holding contraction nonetheless. Right? I'm changing
45:53 , but I'm creating enough force to the load. This is the
45:59 OK. That's just the term we . So when I had this little
46:03 , it wasn't a very big It's a much easier example to work
46:08 . All right, I'm gonna go to the easy one. Concentric E
46:17 and we're just looking at just the , right. We're ignoring the antagonistic
46:22 . All right. We're just looking the agonist. Concentric E, all
46:28 , an isometric muscle on the other , is increasing the amount of tension
46:34 producing. So when I did Concentric and E sent, I didn't
46:38 the amount of tension because the load a constant load. I don't need
46:42 put more tension in the muscle to . Once I've overcome it, there's
46:47 extra tension I need to produce. . But in an isometric, what
46:52 gonna do is I'm going to change amount of tension and I'm not going
46:56 be able to change the length of muscle. In other words, I'm
47:00 tension that is unable to overcome the . So the easy way to show
47:03 this is to look at this right? If I cover this wall
47:07 push on it, you can see putting tension, right? Not a
47:11 of tension, but I'm putting it there. Do you see that?
47:14 , let's watch, the muscle should worn the muscle shirt to be a
47:18 more fun right now. Watch, gonna just keep putting more tension and
47:23 tension. Am I moving the wallet ? Is my muscle changing length,
47:27 it? No, it's not. I can keep putting more and more
47:32 more attention and it doesn't overcome the . A muscle doesn't change length but
47:38 amount of tension being produced changes. that would be an isometric contraction in
47:44 19 seventies when I was a wee . You know, we had public
47:49 television, public television and there was , um, that's where all
47:54 the, the stay at home moms back then you didn't call them,
47:57 at home moms. They were just , right? They would do their
48:01 exercises to the exercise shows that they in the mornings. And one of
48:07 was a guy who would teach them exercises because they're easy to do.
48:14 don't need weights and you can challenge body as needed. So, like
48:18 could go, oh, look at . I'm working really hard. I'm
48:21 the muscles and I'm doing that hard . All right. I'm not doing
48:27 guns. I'm just, I was my guns. All right.
48:36 Ok. Mhm. Yes. It be isometric, right? So you
48:50 think of each movement as having different of movement, right? So for
48:55 , I'm just gonna use this, just pretend this is heavy because it'd
48:58 a lot easier. So me bringing up, that would be iso,
49:03 ? Which one isometric or? So if I just brought this up
49:08 that, what that can do I'll do it this way because it
49:11 , think of the bicep is right? So if I bring it
49:14 like this is that isotonic or isometric now, if I hold this
49:19 right? And I can actually that be isometric. Maintaining that tension,
49:26 ? Without changing. All right. . Yeah. Yeah. Speak up
49:36 , tension. Yeah. So when talking about muscles, the amount of
49:40 that they're doing is referred to as . The thing we're trying to lift
49:44 is called the load. It's just , right? So the tension that
49:49 muscle produces is the amount of work doing to do the job that it's
49:53 told to do. That's a really definition. But I think that makes
50:00 . Yes. Mhm Which muscle are ? Which muscle are you using
50:17 You're using a muscle here, And you're using a little bit of
50:20 delts and a little bit of your . There's a couple of other muscles
50:24 there. No, no muscle I'll just be real blunt, no
50:28 that you do is going to be single isolated muscle. There's usually going
50:32 be at least two or three involved the most in the movement. And
50:35 of it is actually to stabilize your , you know, so you'll have
50:39 agonist, you'll have the antagonist, is basically the two muscles that fight
50:43 each other and then you have other there to actually uh keep you in
50:48 . So like if you're lifting something , your body is not gonna kill
50:53 . So there's primaries and there's secondaries if you go to physical therapy,
50:58 teach you all the fun stuff. . Any other questions? These are
51:04 questions. You, you're thank you being engaged. I like engagement.
51:10 right. When we're talking about an fiber, the contraction in that
51:17 So remember the term fiber refers to cell, mild fiber returns, refers
51:21 the, the, the individual the thick and thin filaments together.
51:26 right. But the fiber when we're about a contraction in that individual cell
51:33 referred to as a twitch. when you think twitch, don't think
51:38 that, you see you're all looking , you're too busy, I'll do
51:41 again. That's, that's not a . You know, it's being
51:46 right? But it's not a twitch is not even visible. It's
51:50 meaning the muscle score is doing And since a whole muscle is made
51:57 of thousands upon thousands of cells, not gonna see a twitch by
52:03 Ok. So this is trying to you what a twitch might be,
52:08 ? So you can see it doesn't a lot of tension. You can
52:11 where the stimulus is taking place. thing about muscles, they're not action
52:16 , an action potential causes a muscle contract, but it's not creating the
52:21 , right? It's not the contraction . So what you can do is
52:25 can take um muscle twitches and you add them together. They're summit kind
52:31 like greater potentials. Yes. Not type of twitch. No.
52:40 So think about it, think about a muscle, just how, how
52:44 it is. I mean, you pick a small muscle like that and
52:47 still gonna have thousands of individual So you're not gonna feel or see
52:52 twitch. You, it's, you even detect it just from the
52:55 You have to actually have an actual mechanical structure that sits on both
53:02 Did you ever, did you ever the physiology lab or have done a
53:05 lab where you've done the frog Oh Dude, this is so
53:10 right? Take the frog muscle, attach it to two electrodes,
53:14 And then basically you run electricity to and you can get it to do
53:18 . It's awesome. It's a dead . Don't, don't worry about it
53:23 its life for you to play. no, so that's what they're measuring
53:26 literally that individual cell here. You do it just simply by putting like
53:30 patch on and saying, can I the electrical activity here? So,
53:34 good question. All right. So can think of this as a microscopic
53:41 , action, right? Nondetectable. right. Now, there are other
53:47 , um, between a twitch. what I wanted to get to is
53:50 term right here, right? It's tetanus. Now, you've learned about
53:55 , that's when you go play out a, in a, uh field
53:58 shoes and you go step on a nail and you don't tell your mom
54:01 she told you put your shoes but you didn't do that. So
54:04 just don't want to get in trouble about three weeks later start walking around
54:07 jaw. No, you haven't heard ? See if some of you are
54:12 , yeah, right now it's called . That condition because of the lock
54:21 . What am I doing? What's of us doing? They're contracting,
54:26 in a constant state of contraction. in a sustained contraction. Sorry.
54:31 right. So that's why they refer it as Tetanus. A tetanus in
54:34 muscle is a sustained contraction. That's it means. And really what it
54:39 is a series of action potentials that happening in rapid succession, causing a
54:45 of twitches to occur so that they're summed up together. But up,
54:49 , up, up until they reach point where they produce tension in that
54:54 . And it's the tension that we're in is how much tension can I
54:59 in a single fiber or only not single fiber? Because typically your muscle
55:05 are grouped together in things called motor . All right. And a motor
55:13 is a single motor neuron. So neuron attached to a group of
55:22 So that when the signal comes down motor neuron, you activate all the
55:26 that are associated to that motor So in our little cartoon up
55:30 we have a motor unit that has . So here are a group of
55:36 , but three of them are stimulated that one axon. OK. So
55:41 is a relatively small motor unit. have different sized motor units. You
55:48 have big motor units and you have motor units. And the more cells
55:51 have in a motor unit, the crude activity that that particular unit produces
55:57 fewer cells you have in a motor . And remember we're talking about
56:01 muscle cells, the more fine activity can do with that motor unit,
56:06 more fine tuning the action. So think about movement for a second.
56:10 you give me an example of fine . What would be something that you
56:16 that requires fine movement, surgery? . Great. Not all of us
56:22 done surgery before. What I That's a good example. What would
56:25 something that is similar to surgery that have all done? Thank you.
56:32 done waves in the air. we've done writing. You know,
56:36 you're writing, that's fine movement, ? Your ability to create swirls and
56:42 and, and all the unique things you write or draw is fine motor
56:48 . OK? And so the reason it's fine motor movements, you can
56:52 say, let's just say we have motor units to allow us to make
56:58 nice doodles. I'm just making up here just so that you can visualize
57:02 I have 10 motor units involved, only have 10% of my motor units
57:07 in the movement. I can add one motor movement and I'm just adjusting
57:12 to 11% or I can bring in more. So I'm up to
57:16 Do you see? So I can very, very small, fine adjustments
57:21 whatever movement I'm doing that are subtle that they have a very subtle effect
57:27 whatever the action is. And so is a great example. Writing is
57:31 great example there, knife fluid type that I can control finally crude
57:38 What's an example of crude movement? ? Ok. That would, that's
57:45 good example. Moving your arm like , walking. How does walking is
57:49 seem like it's fine. Now, is, what we've already talked
57:53 What is walking? It's not right? It's catching yourself as you
57:57 your weight forward. So all you to do is you just got to
58:00 that clumsy, pick up foot, down, pick up foot, foot
58:05 . You know, in this what you might imagine, let's say
58:08 have 100 motor units again involved in and putting down your legs. But
58:14 what we're going to do. So instead of 100 let's say we
58:18 10 motor units would be a better . So if I have one motor
58:23 involved, that's 10% like we started the fine. But if I recruit
58:27 one motor unit, what do I ? That's another 10%. So I'm
58:31 jumping from 10 to 20. If do another one, that's a
58:35 So there is no refinement, there's fine in between. It's these big
58:41 that take place. And so motor can vary in terms of their
58:48 how many fibers are involved and what of activity they're involved in to create
58:53 delicate or coarse activity. All The second thing I'd point out with
58:58 motor unit is you don't want them uncle together, you want them spread
59:02 through the muscle. And I think , I demonstrated this up here
59:07 with, with this in the but I will just throw something else
59:09 here. That feels kind of Right? Do you have tea?
59:15 . Ok. All right. So can see here to do this,
59:21 would have very few motor movements or units involved, right. This is
59:26 little bit heavier. I would have recruit more motor units. All
59:32 But I don't want them all clustered because if they're all clustered together,
59:35 would happen is I would start pulling muscle in a direction that doesn't represent
59:40 whole muscle. I want it to the whole muscle and that movement that
59:44 doing. If we want the muscle go in a particular direction, how
59:47 attached to its tendons or how its are formed, make the difference and
59:51 it's attached to the bone. That's causes the specific direction. All
59:56 So this is light, that's Heavy is right now, you can
60:05 . I've used those motor units, recruited these motor units and so there's
60:08 free ones in there and I can do this one, right? I
60:14 a finite number of motor units. you think I can go curl that
60:19 ? Thank you for not asking me do so, I've had classes
60:21 yo, go give it a I can't. All right, I
60:25 I can't, I can't. All , when you've run out or run
60:33 all your motor units, you can't the tension enough to overcome the
60:36 right. So what you have here a series of motor units that allow
60:40 to adjust how much tension you need produce, to overcome whatever load that
60:46 working with, they're spread out in , so that the whole muscle is
60:50 together. And then the last thing is um I don't think I even
60:56 it on this slide, but I we need to mention it anyway,
60:59 that it might be a later slide to do with fatigue. Is that
61:04 way that your motor units are they kind of act like a 24
61:08 factory. So when I have fibers get tired as long as I have
61:13 available, I can actually rest, fibers bring in other fibers to overcome
61:19 job. So again, this is the lightest thing on the planet,
61:23 it's not the heaviest and I could hold it out here probably for about
61:26 minutes or so. And what I'd doing is I'd be going through a
61:30 of motor units and then those would kind of tired. They go through
61:33 fatigue stage so they would begin to . But I'd recruit in a different
61:37 of motor units to maintain the activity we could just keep doing that
61:42 we could say indefinitely, but eventually might reach a point of fatigue where
61:46 just can't do it anymore. And all the cells just say,
61:49 screw you. I'm not doing this with this. I have fewer motor
61:56 recruited. How long do you I got to hold this like this
62:00 forever. If you guys put a to my head. Yeah, we're
62:03 putting that sucker down. What about bad boy? Now you saw,
62:08 mean, I struggle with it so 10 seconds I could hold it out
62:12 and then I'd be like, I'm done, I've run through all
62:15 motor units. There's nothing else to . So basically the fatigue sets in
62:20 then the system says we're done. nothing here to do the work that
62:25 required. So we protect, we the muscle and we basically stop sending
62:30 signals. I see a look on face, Kendall. That's all
62:35 It be, it just looked like was a question. So, fatigue
62:45 when they basically run out of a . And it's not quite because,
62:50 you're never gonna want to get to point where you run out of a
62:52 . Right. But you're approaching the where I can no longer do the
62:56 that is going to be required of . So, rather than damaging the
63:00 , whether through lock loss of a or through tearing of it, what
63:06 gonna do is I'm gonna send an signal back and basically prevent excitation of
63:12 muscle motor unit. Right. I'm trying to see what we got
63:18 All right, we're kind of jumping stuff. That would be interesting.
63:25 , I mean, we're just limited we got to cover some more muscle
63:28 . Um, there's different types of fibers depending upon their A TP A
63:32 . So we got fast versus slow , fast twitches are the ones that
63:36 you these big muscles, slow twitch the ones that you see in long
63:41 runners, people who do yoga, sort of aerobic activity. All
63:47 And in essence, what you're doing you're talking about the, the,
63:50 speed of the A TPS activity on fiber and also how fast the calcium
63:56 pump. And so they give the different sorts of abilities, right?
64:02 , interestingly enough, we have, we're gonna look at this picture
64:06 let me just ask real quick who dark meat? Who likes light
64:10 So when you look at a you can think white meat versus dark
64:13 in humans, you can't do We can't just say if, if
64:17 a cannibal when the end comes here the next couple of months, when
64:21 comes time to eating your neighbors and , you can't go around saying I
64:24 like dark meat today and you just for a thigh. You can't do
64:28 because all our muscles are a mixture our light and our dark meat and
64:31 what this is a slice through. I just scare you about the cannibalism
64:37 ? Ok. Good. Just making . I think that's the first time
64:41 mentioned cannibalism in the classroom. yeah. Yeah. Well, you
64:45 , well, in the classroom, . Many discussions in the neighborhood.
64:49 in the classroom. Who are we to eat first? Yeah.
64:56 so what you can see here is can see there's these dark cells,
64:59 these medium dark cells and then there's very light cells. And what they're
65:04 referring to here is the degree of that's found in the myoglobin binds up
65:13 . Thank you. That's what I'm for. So these are cells that
65:16 going to play an important role or to be uh not play an important
65:20 , but who are responsible for oxidative . All right. So in other
65:25 , they produce a lot of a , if I produce a lot of
65:27 TP, that means I am a fiber, I can do things over
65:33 periods of time. All right. you're, if you're not tracking
65:39 let's go outside and run real you know, which is if can
65:43 run at top speed for 100 Just not say, yeah, of
65:48 , I can, you're supposed to yes, I know. Just,
65:52 not, of course. All Can we take that out to a
65:56 a kilometer. No. All Let's take it out to a full
66:01 , right? No. So what would have done is you would have
66:04 through all your A TP very All these fast twitch fibers would basically
66:08 I'm done. I'm fatigued and all left with. Now are your slow
66:13 fibers which have a, take too to produce the A TP.
66:17 if you sat there and jogged your through it, you know, your
66:20 twitch fibers would still get exhausted very quickly. But your slow switch
66:23 are like, yeah, I've been A P all along so I can
66:26 on going. And so you'd have problem getting up to that one
66:30 That makes sense. Sort of. aerobic exercises use the oxidative pathways,
66:37 twist. It says these are heavy type stuff. So if you like
66:42 big weights, that would be All right, they are, the
66:50 are fast fatigues. All right. there's basically three muscle types, two
66:54 them are red. So if they're , they're oxidative. All right.
66:58 Lots and lots of myoglobin. very slow, not very powerful and
67:04 fast, a lot less myoglobin. are the white ones. That's the
67:08 muscle. So dark meat like easy way to do a comparison is
67:16 put them next to each other. , so we really don't talk about
67:21 muscle. Um There's just a couple little features here, they behave very
67:26 to skeletal muscle. One of the features here, which we'll spend more
67:30 talking about is that they are not , as long as the structure
67:35 they actually, it's cell to cell cell. And what you have here
67:39 the attachments between cells are called inter discs. So basically one cell pulls
67:44 the other cell. Um but you have sarcomere, they're just not as
67:49 as, as the skeletal muscles. second thing we mentioned that you have
67:57 protect, you don't have a terminal , just not enough space.
68:02 but it's the same sort of Calcium goes in. Um calcium also
68:08 just sequestered away in the sarcoplasm It's actually surrounding the muscle of the
68:12 . So when they are triggered, actually open up receptors that allows uh
68:17 to flow in from outside the And so they get a contraction in
68:22 exact same way from calcium, the same way as just how the where
68:26 calcium comes from. So this is an example. So yes, you
68:30 have sarcoplasm particulate, but you also calcium on the outside. And so
68:36 they come in and do the exact thing, right? So cardiac
68:43 very similar to skeletal muscles, slight , smooth muscle. On the other
68:49 , uh a little bit, it's so different that it's like scary,
68:54 you'll see it and you'll be like is different and different is scary.
68:58 , but it shouldn't be. All . First off, smooth muscles exist
69:01 one of two ways. They can found as multi units or single
69:05 I always flip these things around in head. So you need to come
69:08 with a good way to remember Multi units means each of the individual
69:12 are being innovated and act independently of other. OK. So if the
69:19 of us are smooth muscles, we're talking to each other. I'm being
69:24 by myself. He's being stimulated by . She's being stimulated by herself.
69:29 neurons doing that stimulation. That's multi . So we each independent units of
69:33 other. The single unit on the hand is where you have the cells
69:38 a sensi, they're connected to each via gap junctions. You also have
69:43 the surface, you'll have a The neurons that are typically associated with
69:48 muscle have varicosities. So they they're not creating a neuromuscular junction.
69:53 , they're just kind of like sprinkling over the surface of the cell.
69:57 the cells that have the receptors, of them have receptors, you'll,
70:01 be contracting at different times and different . It's just a little weird,
70:06 ? But you'll still get a contraction the whole unit because even if I
70:12 stimulate one cell because of the gap , they'll tell the other cells to
70:19 the type of contractions. You see , these are called either slow wave
70:23 pacemaker potentials. Depending on the type wave means that the cell is undergoing
70:28 series of pulses in terms of allowing uh depolarizations. But the depolarizations may
70:36 actually be reaching threshold. What will is is that something will cause you
70:42 pulse up to the point where you to the threshold, where you get
70:45 series of action potentials. And then that's maintained, you can still keep
70:49 series of action potentials. But it's back and forth. Like so you're
70:54 just kind of cruising along, going a series of not getting high enough
70:58 create a series of contractions. It's action potentials or not a potential,
71:03 graded potentials until you reach that threshold potential. On the other hand,
71:08 you're just going to go through an potential, then you come down to
71:11 and then you start returning back up to slow wave, except that you're
71:15 needing some outside stimulation. In what you're doing is you are going
71:21 threshold at a particular rate and then get the action potential, then you
71:25 down below threshold and then you slowly back up to threshold. So it's
71:31 like a constant state like so these just examples to show you, but
71:36 don't need to go into deep talk how they're different. And then
71:44 the model that you need to keep your head is you need to understand
71:47 skeletal muscle contraction. And then what gonna do is we're going to move
71:51 from that. So what are the ? First? There are no
71:55 All right, I love this picture it looks like a ham that's been
71:59 up. Instead, what we have we have dit bodies. And so
72:03 dit bodies are represented here at these points. The same proteins that make
72:09 Z discs are the same proteins that found in dense bodies. So,
72:13 structure, we have thick filaments and have thin filaments, but we also
72:18 intermediate filaments. And what you do you create this lattice along the the
72:24 of the entire cell. So, essence, when a contraction occurs,
72:30 not pulling in one direction. I'm pulling the ends of the cell
72:34 What I'm doing is I'm pulling the cell towards the center of the
72:38 And so that's what you're kind of here is, here's a cell that's
72:40 relaxed. Now, here I am the ham, right. So those
72:46 the two states, the method through we do, this is going to
72:51 a signaling cascade. All right. calcium is still involved. A TP
72:56 still involved. The difference is, how it does its job it's gonna
73:01 through a signaling cascade. All there are two molecules here that inhibit
73:06 role of mycin or the uh the activity. Calpine, Calpine is going
73:12 bind up to Acton and basically prevent P activity. So you can see
73:17 , it's an inhibitor, the N inhibitor caldesmon blocks the uh interaction
73:25 So it kind of interferes like trip does. Now, I'm gonna
73:31 kind of keep this as simple as can because it gets uh it can
73:34 , get kind of crazy here. right, calcium comes into the
73:39 So you can see calcium is flowing . But what it's gonna do is
73:43 going to activate a signaling cascade. right. And the signaling cascade is
73:48 to be done through calmodulin. You good old calmodulin. All right.
73:55 calcium comes along, activates calmodulin. activates a molecule called my light chain
74:02 . Have we heard the term myo chain? Where was the light chain
74:08 at the hinge? Right. So is where that a TP A activity
74:12 taking place. All right, what and light chain does or the K
74:17 it phosphors the hinge. And so changes the A TP A activity.
74:24 right. So what you're doing is changing the hand, changing the
74:28 So the degree of contraction that's taking is being modified through calmodulin. You
74:35 have to worry about troy because all gotta do is not allow calcium to
74:40 in. And if there's no you're not going to get an interaction
74:44 you'll get an interaction, but you need to break it. It's just
74:46 of being held in place. There's reset that's going on. But when
74:52 have calcium, I'm going to change activity of that. A TP A
74:58 so what I'm gonna do is I'm to change how much it's contracting and
75:03 . All right. I have a as well. Calmodulin kinase two.
75:10 does it do? It inhibits the if I inhibit an inhibitor, what
75:17 I do? I excite? I All right. And so this is
75:22 is also allowing it to happen. then the other thing that calcium can
75:26 , it activates or sorry, it up Calpine. And so we remember
75:31 we said Calpine is the inhibitor of interaction. And so if I get
75:35 instead of it binding up to trot , it's binding up to this and
75:40 doing the same thing. It basically , go ahead and interact. So
75:45 steps are different because of the molecules are present. But all the things
75:50 we did in skeletal muscle we're doing . OK. I know I see
75:57 blank. Look over there. I you're just going, I'm not
75:59 I'm not necessarily you but I'm just . Yeah. Mhm Yeah. Mhm
76:06 , it binds to troponin pulls So troponin is the calcium binder.
76:12 remember it had three parts TNC TT I and TNT because it's dynamite.
76:20 you. I, I have the jokes. I'm sorry, I'll just
76:24 lobbing them until I get a Ok. Seven. Well,
76:34 so you can think about what is doing? Troponin is the hinge that
76:39 triple to stay in place. So calcium comes along, it moves the
76:44 so that it no longer impedes or here, we don't have Tropomyosin
76:49 What we have is we have Konin is kind of acting like Troy and
76:55 together. And what we're doing is saying, oh, when calcium comes
76:59 , it blocks or prevents calum from what it wants to do. So
77:03 action in my can interact. So , that's the thing. But the
77:09 is, is what is the calcium ? It's not pulling something out of
77:13 way it's interacting and activating cascades. , if all this is confusing,
77:21 like, OK, I need to the differences, cardiac, not so
77:26 . I mean, just basically the muscle with those two little things.
77:30 if you want to compare and this is the compare contrast slide.
77:37 right. The good news is that muscle, I'm not going to come
77:41 and beat you up with it. right, if you got skeletal muscle
77:46 , you're gonna answer most, you'll most of the questions coming from
77:49 You might see a smooth muscle You should see at least one smooth
77:54 question. So next time we meet Tuesday. Next week. Thursday we
78:04 an exam. Yay exam. You're at it wrong. You're just
78:08 oh, I'm gonna be tortured. , no, no. That,
78:10 means we're halfway done with the You're halfway done with me. I
78:15 almost done. I am almost That's, that's how you do
78:18 You go take the test, find nice place for a happy hour.
78:24 know. What's that? I
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