[00:00:00] Speaker A: Muscle is a perfect system to look at that because you have a protein called myosin, which we'll speak about in just a little bit.
And myosin has to be assembled in vast arrays of probably quadrillions.
I mean, just huge numbers. They all have to be lined up and they all have to be able to generate the force so that even though each one has such a teeny tiny amount of force, when all added together, you can get something meaningful that can do movement at the level of the body.
[00:00:36] Speaker B: ID the Future, a podcast about evolution and intelligent design.
So every movement you make walking across a room, lifting a cup of coffee, even blinking your eyes depends on trillions of microscopic molecular machines working in remarkable coordination.
Welcome to I Do the Future. I'm your host, Andrew McDermott. Well, today we're going to explore the hidden machinery of muscle with Dr. Robert Walzer, professor of biology and long term researcher and lecturer on Intelligent design.
In case you don't know about him, Dr. Walzer is currently the chair and professor of biology at Belhaven University in Jackson, Mississippi where he's been teaching for over 30 years.
He has a PhD in anatomy from Ohio State University where he focused on the anatomy of the brain. He teaches courses on human biology and is a leader in the division of History and Philosophy of Sciences at the Mississippi Academy of Sciences where he was recently awarded the designation Fellow of the Academy. He is the co author with four authors of the book Evolution and Intelligent Design in a Nutshell. He has been doing research and has given presentations on intelligent design, often at secular conferences for many years.
Well, Robert, welcome to Idea of the Future.
[00:01:55] Speaker A: It's good to be here. Andrew.
[00:01:57] Speaker B: Yeah, no, we spoke some years back during the whole Covid era when that book first came out, Evolution and Intelligent Design in a Nutshell. It's a nice sort of introduction to some of the arguments for intelligent design.
But we're here to talk today about muscles, and you are quite the expert. You've been teaching this, you've been steeped in the literature and really studying this at a deep level. And we just want to pull some of that insight out today. This is the first of two episodes actually. There's so much to this that we're going to unpack it over over a series of two shows. But today I just want to kind of set the stage a little bit. Now before we dive into muscle biology, tell us a little bit about how you first came across or came became interested in intelligent design.
[00:02:49] Speaker A: Well, soon after arriving at Belhaven in 1993, the philosophy professor Gave me the book Darwin's Black Box by Michael Behe. And he also gave me some books by Philip Johnson. He actually had some videos of Philip Johnson doing debates with other people.
And so that really got me into it. I didn't know it as intelligent design. I was already a Christian. I was already interested in creation and evolution.
But this, this really seemed to be a way of bringing the argument kind of the mainstream because it was focused on science, not religion.
And so. And as it turned out, I ended up doing a. Something called a seminar in Christian scholarship at Calvin University in the year 2000.
Calvin used to have a series of these seminars. I don't think they do them anymore, but it was like four or five weeks over the summer. And it was called Design Self Organization and the Integrity of Creation. And Steve Meyer was there, Paul Nelson was there.
Many other people in the movement that have written books were there.
And so I got to interact with them and interact with other scholars. And then I also got a chance to come to a summer seminar at discovery in 2017.
And, and that. I know it's mostly designed for students, but some faculty do go. And it really interested my, reinvigorated my interest in intelligent design. I never lost interest, but it kind of, sort of gets kind of routine and kind of into the background, and it really kind of made it stand out. And so much so to the point that everything I taught, as I would go into it, I would pause for a moment and just think about what I just said and how amazing it was and how could this come together and how could this do what it's supposed to do and just continuously exclaiming, you know, as I'm teaching, but building it right into the fabric of the lecture. And so that, that kind of really supercharged me.
[00:05:05] Speaker B: Well, I'm glad you got the chance to participate in one of our summer seminars. Those are great for students and teachers alike.
[00:05:12] Speaker A: I strongly recommend them. Yes.
[00:05:13] Speaker B: To kind of light the fire and, you know, get that curiosity peaked with some amazing presentations firsthand, you know, with. With those who are in the intelligent design movement.
Well, you've taught muscle physiology for years. What first made you realize there was something remarkable about muscle at the molecular level?
What set the fire there?
[00:05:36] Speaker A: So, like, as I was saying in that summer seminar in 2017 with Discovery, I became really sensitized to things. So that just everything that I'm teaching on, I would, I would kind of put it in a framework of what problem is this solving and how is it doing it?
And, and how well is it doing it and how, and how it's like a genius level solution that's being applied to the problem. And so I kind of applied that, the muscle and the thing that really grabbed me with muscle, the problem is how extreme an extremely small molecule that can generate an extremely small amount of force when harnessed in large amounts, can pull things that are billions of times its size and weight.
And that really, really grabbed me. And I had to think about that. I tried to, and I tried to answer that problem in various ways. Just kind of, kind of looking, you know, moving it around a little bit, looking from different angles, but that's really the problem that grabbed me. And then once I got into that, it pulled me into a lot of other things. With muscle also.
[00:06:50] Speaker B: Okay, yeah, yeah, I, I, as you were talking, I was thinking of, you know, some of the world records that have been set, you know, by human being pulling a car or, or lifting, you know, just an amazing amount of weight. And you wonder how, how is that possible? And it goes right down to the molecular level.
And I'm excited to unpack that so that our audience sort of gets a grasp of what's going on way down in the microscopic level so that we can, you know, lift the things that we can lift and indeed move.
Now, you recently gave a presentation to the Mississippi Academy of Sciences, and you mentioned three converging interests. Muscle physiology, proteins with multiple conformations and molecular motors. Now walk us through how those three threads come together to be the work that you've been focusing on.
[00:07:47] Speaker A: Sure.
So first, I taught on muscle in many different courses of human biology throughout the years.
Physiology courses, anatomy and physiology, where I look at how muscles work at a large level and move parts of the body.
But then I also taught a course in microscopic anatomy, and in that we really kind of delve into the cells and the components that are within the cells and how they work, and in the case of muscle, how all its components are working. And so I've kind of seen it from both ends and one, and so that's kind of the first thread of my experience with teaching. The next thread is I been looking at proteins probably for the last seven years or so in all kinds of different angles of the proteins. And one of them, one of those angles that really grabbed me was how some proteins can have multiple conformations. And I'm not just talking about two, like an on, off switch, they can just begin a series of transformations literally from one shape to the next to the next. They may go through seven different changes before they cycle back to the beginning, these steps are all in sequence and they're all triggered by something.
It might be something attaching, something detaching, or just the previous step triggers it. And so you have all these built in triggers for each step. And so I was just really fascinated by that.
And then the third interest and what I found was that one of the best examples of proteins that went through a lot of confirmations were motor proteins. And motor proteins are proteins that move something. They generate some kind of physical force that either pushes themselves or pushes something else.
And so I began looking at that, and in particular I looked at. Muscle is a perfect system to look at that because you have a protein called myosin, which we'll speak about in just a little bit.
And myosin has to be assembled in vast arrays of probably quadrillions.
I mean, just huge numbers. They all have to be lined up and they all have to be able to generate the force so that even though each one has such a teeny tiny amount of force, when all added together, you can get something meaningful that can do movement at the level of the body.
[00:10:28] Speaker B: Wow. Interesting how all those three things came together for you. Now, you've closely studied the force that muscles can apply to the body to allow us to move and be active. This force you're talking about, but you've also looked at the negative side of this force, which is the stress and the strain that occurs as muscle force is being used.
Now, this is just a really interesting part of this whole conversation. You've got the force of muscle, but you've also got the result of that force, which is damage. Right, right. Tell us about the damage that's occurring regularly within muscle.
[00:11:06] Speaker A: Yeah, so when you think about muscle and you think about force, just about everybody that has any exposure to muscle knows that it generates force and they know the molecule inside of it that generates that force.
But they don't think it through logically, step by step, necessarily, in that the only way for muscle to exert its force is to exert its force on other molecules in the muscle.
And so they are, in a sense, the receiving end of those forces. And since those forces are so tremendously powerful when added together, that that can really create some issues of stress on these molecules. And they will become bent, their positions will shift. In fact, their positions could get shifted so much that the muscle could get damaged and, and as it's generating force, create more damage.
But, but anyway, the positions of the force, so the force generating molecules, their position shift as their they're exerting their force, but the receiving molecules, their positions and their shapes become distorted.
And so anyway, that can. That can get things out of position, but it can also create damage to these molecules.
And if the molecules are damaged, then that could lead to worse and worse damage if not taken care of rapidly.
[00:12:40] Speaker B: Yeah. And the system has to have a way to deal with that damage on an ongoing basis, pretty much in real time. Otherwise our muscles would quickly degrade and get destroyed, wouldn't it?
[00:12:51] Speaker A: Right, exactly. Yes.
And so muscles do have systems for handling that, which I never really had been aware of until I kind of dug into things.
But the damage can be repaired and parts can be replaced.
And so, in fact, that is ongoing. That is kind of a continuous process, even during the contractions, really. And so some small percentage of the molecules are being replaced and new ones are being put in place, and. And things that are damaged are repairs. So you're getting things back up to the way they were. But the fact is, as more force is exerted, more things will get damaged and so more of these repair mechanisms. So it is really a continuous level of activity going on between the rate of damage and the rate of repair and replacement that's going on. And as long as those are equal, we're good and the muscles work.
[00:14:01] Speaker B: Yeah. And there are some problems when that becomes unequal. And we'll touch on that later. Now, throughout this episode, I'm going to put up. We're going to put up on the screen, if you're watching this, of course, just some images, and we also have an animation clip that's going to show you going from the macro level, muscle fiber, you know that, and. And then kind of going right to the microscopic level to see some of these structures that, Rob, you're going to be telling us about. So, audience, be prepared to. To see some of this. If you're watching the video now, Rob, can you remind us just of the basics of how muscles are organized? You know, we. We've all had biology at some point, but it's good to get the reminder of the basic structures we're talking about.
[00:14:52] Speaker A: Yes. So one thing to remember is that muscles only contract.
That's all that they can do.
And so when you do a movement, you're doing that movement because a muscle's contracting.
Now, if you're reversing that movement and going back to your starting point, the another muscle kicks in that is maybe on the other side of your limb, that pulls your limb back to where it was.
And interestingly, when your limb gets returned to its initial position, the muscle that first contracted, that made the limb bend, will get stretched passively, and so it will get reset to its starting position.
So muscles only contract actively, but through force is pulling on them. They can reset to their starting position.
Now.
So that's kind of the general idea of how muscles are situated on the body and how they do things.
I could talk about a little of the organization inside of muscles, if I may. A lot of people think of muscles as cylinders. Not all of them are cylinders, but some of them are.
So that's a good way to think about it, that a muscle is a cylinder. It's like a tube, and that'll have smaller tubes inside of it. And the smaller tubes inside of it are called fascicles. And so it'll be chock full of fascicles all the way through.
And the fascicles are tubes that are running the length of the muscle.
Now, the fascicles have tubes inside of them, and the tubes inside of them are the fibers.
And the muscle fiber is actually the cell of the muscle fiber. Everything in your body has to be made of cells, some, somewhere, somehow. And so whenever you're talking about something, you have to find out where the cell are. And that's where the cell is in muscle. It's the muscle fiber. But the muscle fibers are tubes also. They're unusual cells because they're the length of the muscle.
And. But it doesn't stop there.
The muscle fibers which are the cells have smaller tubes inside of them.
And those tubes are called fibrils or myofibrils.
And these fibrils are tubes that are real tiny. There are hundreds of them within a muscle fiber, and they run, again, the length of the whole muscle. And they're made of segments. And that's where we get into the contraction process.
The segments that these fibrils are made up are called sarcomeres.
So sarcomeres are like little segments of a tube attached end to end to end all the way down the length of the fibril. Every fibril has multiple sarcomeres, end to end, and then there'll be another fibril beside that, which will have its sarcomeres, et cetera. And so now, the sarcomeres themselves have an internal structure, which we could talk about in a moment. But the key thing is the sarcomeres are what does the contraction.
Okay, so when you're asking what is contracting in muscle, it is that segment, the sarcomere. And as each set of sarcomeres contract, they contract the fibrils, which, in Turn, contract the fibers, and you can see we build all the way back up the scale until the whole muscle contracts.
[00:18:23] Speaker B: Okay. So when you flex your muscles and you're lifting something heavy or walking with your legs, you're. We're drilling right down to what's actually doing the pushing and pulling.
[00:18:36] Speaker A: What you said is not wrong, but I like the bend over backwards to be careful because I'm, I'm. I'm thinking as a teacher, you know, and if you give somebody a little bit in the wrong path, they'll take it and run with it.
Muscles don't push.
They never push.
They only pull.
[00:18:55] Speaker B: Right.
[00:18:56] Speaker A: And the thing is, you can push, you know, you can stand up to a wall and push it or push a lawnmower or something like that, but it's because of contractions of muscles. Okay, so there's no forces generated by pushing at the molecular level. It's always pulling.
[00:19:16] Speaker B: Okay, see, and that's something I forgot from my biology classes, you know, and. Yeah, you've been reminding us here.
[00:19:22] Speaker A: My students forget it all the time.
[00:19:25] Speaker B: Muscles only contract. So one muscle contracts and then another muscle will reset that one passively. Is that, that's.
[00:19:32] Speaker A: Yes.
[00:19:33] Speaker B: That's the sort of push and pull we're getting.
[00:19:35] Speaker A: Yes.
[00:19:36] Speaker B: Okay, so the sarcomere is at the microscopic level where it's all happening. Right. Now you said the myosin is the motor protein that is generating the force, and the actin filaments are passing the force to the Z lines. Now tell us about Z lines. Is that. That's within the sarcomere, right?
[00:19:56] Speaker A: Yeah. Well, let me back up just a little bit, if I may.
So if, if you're happen to be looking at an image of a sarcomere. But even if not, when you look at a illustration of a sarcomere, you see these bands going that, that are centrally located that are going from side to side.
And those bands contain the motor protein myosin.
And they're made up of an. Each band is made up an aggregate of myosin, a lot of myosins. Each myosin molecule, it's a long, thin molecule, kind of like a golf club with heads at the end, and the heads are sticking out at the ends. And if you're looking at illustration, you'll see little nubby things. And those are the heads of the myosin. Those heads are able to do the force generation.
So what do they work on? Well, there's another type of filament in muscle that is attached to the ends of the sarcomere.
And that is called actin. All right? Or thin filaments made up of actin molecules.
And the myosins grab the actins and pull on them. Now, the myosin, the thick filament, is set up in a symmetrical way, like one side is a mirror image of the other.
So one side will pull the actin filaments toward the center, and then the other side will pull the other set of actin filaments also toward the center. So those two different sets of heads are pulling in different directions, but they're pulling both actin filaments toward the center.
The actin filaments are anchored to Z lines, and the Z lines are the boundaries of the sarcomere. So when the Z lines are pulled, the sarcomere gets shorter, and that's contraction.
[00:21:46] Speaker B: I see. And this is going on, you know, there's. There's multiple sarcomeres, obviously. I mean, what are we talking here? Millions of them or.
[00:21:57] Speaker A: Yes, for sure.
Probably trillions of them. In a muscle the size of your biceps?
[00:22:04] Speaker B: Yeah. All working in tandem at the same time?
[00:22:08] Speaker A: Well, yes and no.
[00:22:10] Speaker B: Okay.
[00:22:11] Speaker A: Depends the strength of contraction. If I'm lifting up a pen, then I don't need as many sarcomeres activated. So a subset of my. Basically, you have to activate a whole fiber. That's the smallest unit that you could activate. But all the five myofibrils and all the sarcomeres in that will get activated in the. In the one muscle fiber. But you don't activate every single muscle fiber.
And then if I'm doing a lift, lifting a book, then, you know, it's a larger set of muscle fibers will get activated. And then if I'm trying to lift up a sofa or something like that, then it's close to a maximal contraction, and then a large percentage of them will get activated. So it depends. You have control over how many you activate to regulate how much strength you want to generate.
[00:23:05] Speaker B: Okay, that makes. That makes perfect sense. So I can turn around to my kids when they want to relax and. And watch TV all day. I can say, kids, get up. Activate your sarcomeres. Let's. Let's get moving here.
Yeah. Okay. Well, now, here's a side question, but. But interesting nevertheless. How are scientists even able to know what's going on at this level, at the microscopic level in muscle?
[00:23:33] Speaker A: Have.
[00:23:33] Speaker B: Have we seen sort of an advance in technology that gives us this greater glimpse?
[00:23:40] Speaker A: Well, muscle's been studied for over a hundred years, and the techniques of the times were used when, with the technology available at the times initially, very crude extracts were made trying to isolate sets of proteins and observed what factors cause proteins to detach from each other or assemble to each other.
But things really picked up with electron microscopy in the 50s and, and so in the 1950s, electron microscopy gave images of what was going on. And actually that's when people really visualized sarcomeres and they were ab able to see actually the different filaments, the long thin threads and various bumps in them.
And you know, the muscle lends itself to X ray diffraction. Lots of X ray diffraction has been done on muscle and as well as electron microscopy to figure out how the proteins are organized and assembled and interacting with each other.
And there really are sets of brilliant experiments that combines anatomy, physiology, physics and electricity. I mean, just so many different factors were put together and they would make incremental steps and put things together really. The, the full, I don't know that the full picture has even been arrived at, but a good working picture probably was.
That is much more complete. It's like mid to late 80s.
So it's like within our lifetimes. Yeah, so it's amazing.
And as they get more and more technology, they're looking at the shapes of proteins and they're doing genetics of the sequences of the genes that code for the proteins and modeling how the proteins are attaching to each other and changing shape. So there, there's just lots of high tech stuff going on, crude stuff to all the way to the most advanced high tech.
[00:25:59] Speaker B: Interesting.
Well, I just want to touch on one more thing at the technical microscopic level before we wrap up today's episode, and that is we talked about the Z lines, which are sort of the boundaries of the sarcomere.
You also hear of Z disks. Now, are those the same things?
Tell us how that's working out.
[00:26:22] Speaker A: Sure. Well, if you're looking at an image like a drawing of a sarcomere, most of the time you're looking at just a flat image, like a two dimensional image.
And so the end, the boundary of the sarcomere is a line.
But keep in mind that that's not truly how the sarcomere exists. The sarcomere is a segment in a tube, so the boundary of it is a disk. So if you made a slice through a tube and then looked at the cut end, you would see a kind of a circular area and that is a structure, the z dis. The Z disk.
So a lot of times people use those terms interchangeably.
To a certain extent you could say that a Z Line applies more to a two dimensional drawing, while a Z disk applies more to a three dimensional view of a segment.
[00:27:21] Speaker B: Okay.
All right. But the sarcomere is definitely where things, where the action is happening at the molecular level.
[00:27:31] Speaker A: Yes, yes.
And did you want me to say a little bit about the Z disk?
[00:27:38] Speaker B: Yeah. Tell us, tell us more about how that fits into this system here.
[00:27:42] Speaker A: Okay.
So as I began looking into the Z disk, I ran into a whole realm of complexity that I had no idea existed.
To some extent, the drawings of the sarcomeres are misleading because they try to make it seem like there's just a single molecule connected end to end that forms a Z line or Z disk, when in fact, it is a extraordinary complex of proteins altogether that are forming this Z disk. A lot is packed in to a really small area.
The key protein in the Z disk is, is called alpha actinin.
And that forms the framework of the Z disk.
And if you hear that word actinin, that reminds you maybe a little bit of actin. Right. And it got named after actin because it attaches to actin.
Anyway, these alpha actinins in the Z disk brace the actin filaments that are extending out of the Z disc and into the nearby sarcomere.
Now, keep in mind that we said that sarcomeres are attached end to end.
So that means any given Z disc has a sarcomere on either side of it.
And so each sarcomere has actin filaments that are attached on the Z disc and extending into the sarcomere. So what you actually have are two sets of actin filaments that are kind of extending outward from the Z disk.
And when they are pulled on, they are both pulling on the Z disk equally on both sides. And actually, that's a beautiful example of fine tuning in that the stresses are balanced.
So if you just pulled from one side, it would just tear everything to shreds. But by having the forces balanced, um, they are, they're not damaged as much.
Now. What are they pulling? They're attached to alpha actinins. So alpha actinins are some of the key molecules that are the framework of the Z disk. There are actually a lot of other molecules and these, they're all important in various ways, but you can kind of ignore those for now and just focus on the alpha actin as forming the framework of the Z disk and the attachment points for the actins that are getting pulled on in each sarcomere. In each adjacent sarcomere.
[00:30:24] Speaker B: Yeah. And as I mentioned, we're putting up images as you're talking about this detail just so we can get that visual. Look at this. So you're basically painting the picture of this incredibly efficient system, intelligently designed. And also foresight is built into this, too, because, you know, you anticipate damage and there's repair all in real time while the muscle is being used at the macro level.
So all of this requires a lot of fine tuning, and we'll talk about that in the next episode as well.
Now, all this force generation done by muscles creates a serious problem.
That problem is damage and the repair needed. So that's where we're going to pick up things next time. Because somehow muscles survive this constant stress and damage through remarkable systems of stabilization, repair and replacement.
I'd like to talk more about that with you next time.
[00:31:24] Speaker A: Sure, that'd be great.
[00:31:26] Speaker B: Okay. Well, Rob, thanks for coming on the show. This is fascinating stuff. I mean, I'm taking notes and being reminded about things I studied years ago. You're steeped in this, and my hope is that we can just, you know, really give a new appreciation to our listeners and viewers of how we move and the muscles that allow us to do amazing things. So thanks for coming on and let's look forward to the next cycle.
[00:31:50] Speaker A: Glad to do it. Look forward to it.
[00:31:53] Speaker B: Now, a reminder that ID the future now has its own YouTube channel. So you can be watching these interviews that we're doing as well as listening to them if you so choose. Our YouTube channel
[email protected] d the future.
Do us a favor. Subscribe there so you can be the first to receive these videos as they come through. And don't forget, another way to do this is to share the podcast with a friend. We're trying to build this audience. We're trying to get the evidence for intelligent design out there. And you've got friends, you've got associates, you've got family members who have questions, who are skeptical, who think this could all be a fairy tale intelligent design, or they just don't know the level of detail that you've learned. So you can help us by sharing these podcasts with others. We really appreciate your help. Well, until next time. I'm Andrew McDermott for ID the Future. Thanks for joining us.
Visit us at idthefuture.com and intelligent design.org this program is copyright Discovery Institute and recorded by its center for Science and Culture.
