[Music] Hello and welcome to cellular biology. My name is David Woodruff and we're going to talk a little bit about the basic cellular biology that is necessary to be able to understand the concepts of pathophysiology. So just to begin with, let's take a little bit of a review here of what a normal body cell might compose of or might look like. So this is a cutaway view of what a cell might look like and we can take a look at some of the different components inside of that cell. Now we're going to talk about some of these in a little bit more depth and certainly there's more discussion of the different components of the uh inside of the cell here in your book. So that's another possibility if you wanted to gain a little bit more knowledge about some of the different components. Starting on the very outside of the cell, notice that there is a plasma membrane. And this differs from the cell membranes that are included in bacteria, for example. Uh so the cell me the plasma membranes of a human cell are going to have some functions we're going to look at a little bit later that are going to help to move water and to move electrolytes in and out of the cell so that they can be used by the cellular functions. We have a number of other pieces inside of that cell. Just a couple to take a look at. There is the lossome over on the right hand side. Small little round. And in this case here, they've got it as kind of a light green thing. Those are the digestive organs of the cell. So those are the digestive organs. We have the nucleus there in the middle. The nucleololis is going to be the very center part of the nucleus. Down on the bottom, we have the mitochondria. And the mitochondria are involved in the process of developing energy for the cell. So obviously very important organel in keeping that cell running appropriately. We also have the ribosomes which are going to be important for the um the ability of that cell to be able to replicate. Now we can divide ourselves down into two main categories. We have our proarotes and we have our ukareotes. Our proarotes are going to be those that uh involve no distinct nucleus. So there's a lack of histones organels etc. And so this is going to be the kind of cells that we're talking about when we talk about bacteria for example. Now the other type of cell there the ukarotes these are going to be cells that have these are basically our our higher animals and plants etc are going to have a ukareote type and this is going to be a membround organels like we see in the human cells well- definfined nucleus several chromosomes etc. So a little bit of a difference between different kind of cell types. Again, hopefully this is just review for you from your anatomy and physiology, differences in their biochemical ability or capabilities between proarotes and ukarotes as far as protein synthesis, transport across the membranes and enzyme activity as well. Now, some of our cellular functions that are going to happen with our cells could be movement. So that may be a possibility. There may be movement of the cell. So the cell can move in a couple different ways. Maybe it's a cell that is going to create movement such as a muscle cell. A cell may also move by just kind of like a little amieba kind of, you know, moving around as well. So that may be another possibility depending upon the type of cell. Alth also as far as movement goes, we can also have movement from the standpoint of movement from some other body source such as from the bloodstream or the lymphatic system or something else is moving that cell throughout the body. the possibility of conductivity. Not all all not all cells have this intrinsic ability to be able to conduct electricity. But certainly some cells like our nerve cells do have that ability to be able to conduct electricity. Heart cells and muscle cells have that ability so that we can spread an impulse across that heart or muscle cell in order to make it contract. Metabolic absorption. So the ability to be able to absorb the uh nutrients that it needs. Secretion. So being able to secrete substances that may be necessary for promotion of other bodily systems such as hormones. Excretions. So the cell is going to use nutrients and excrete them. Respiration which is the process of using oxygen. Reproduction of the cell. Well, okay. So if we're going to get new cells out of this, we need to have reproduction. And then communication may be possible between one cell and another. Now we do understand this to some extent with cells like nerve cells etc. But there may be some communication that's occurring between cells that uh we don't understand as well. Maybe one of your liver cells is communicating with other liver cells in a way that helps to either prevent or to encourage disease. As far as our ukareotic cell, we have our nucleus being the center part, the brain kind of as you will of the cell itself. And this is where we have our DNA. we have uh the information about cellular division about genetic information all that kind of stuff is included there in the nucleus. So this is a picture here showing the nucleus and specifically pouring pointing out to us a pore in that nucleus given a little bit more information or a little bit more detail here. Now we can start to see on the outside of that nucleus there is this nuclear envelope and that's the part that contains the nuclear pores. Then we have our uh nucleololis inside with the chromosomes etc. And that's going to be our main information for the cell as far as dividing and creating more cells like it. The nucleus also is going to contain within it our DNA. And this is just showing the process of DNA formation. and DNA. U we're going to talk a little bit more about how DNA is going to divide and create a new cell. The cytoplasm is the water part of this ukareotic cell which is going to kind of keep everything in place. If we didn't have the cytoplasm, basically the cell would just kind of shrink up into this flat thing that contained a bunch of stuff and there wouldn't be any form or function to the cell. So the cytoplasm first of all is going to be important for maintaining the shape and the size of the cell. It's also going to be important for some functions. We have to keep some of these organels away from each other in order for them to be able to function. Kind of like having a bunch of electrical wires touching each other and shorting out. If our organels are all touching each other, we may not have good function between them. So again, this is another picture here showing what the inside of the cell looks like and a little bit more detail of what that ukareotic cell would look like with our cytoplasm. And you notice the cytoplasm is holding the different structures away from each other. Without the cytoplasm, all these structures would just kind of collapse into each other and we would just have this big blob sitting there that probably wouldn't be functional because we're not uh the different components are touching each other. and may be interfering with each other. For example, the lysosomes, the digestive part of the cell, uh could be digesting the internal organs of the cell and creating dysfunction. So, what are some of the organels that are inside our ukareotic cell? We have our ribosomes. Our ribosomes are the place inside the cell where we contain our RNA protein. And we have both free and attached ribosomes. The free ribosomes are going to be free floating as opposed to attached ribosomes. We have our endopplasmic reticulum. This is going to be the site where we have our protein synthesis within the cell. We also have our golia complex and this is the area of the cell where those proteins are come from the g from the endopplasmic reticulum. Those proteins are going to be packaged up here in the goli complex. It also has the ability to with through these secrettory vesicles to be able to release some of those proteins to neighboring cells if necessary. We have our loss. They originate from the goli, but they are going to be our little digestion part of the cell. It's kind of like the digestive system of the cell. So, it's going to catabolize our proteins, our lipids, our nucleic acids, carbohydrates. So, in other words, it's doing the digestion and it has a role in the autodigestion of the cell. So just for a moment, if we were to stop here and say, okay, what would happen if we destroyed a lossome? The lossome did not get enough energy that it needed in order to be able to function and the lossome just kind of deteriorates and becomes destroyed. Well, it's going to release those enzymes that are inside that lo digestion. And those enzymes are going to get out into the cell as a whole and start digesting that cell. So this is one of the things that can happen when somebody has a condition where maybe they're not getting enough blood flow, not getting enough oxygen to their cells and cells start to die. We get permanent damage to the cell caused by the lo digesting the internal components of the cell. Now these things here are called peroxyosomes. Uh you may have noticed by looking at the word, doesn't it look like the word contains the word peroxide? Okay, peroxide is a chemical that is going to oxidize. In other words, it's you put it on certain things like you put it on a wound and you see it kind of foam up. And the reason it's foaming up like that is because there's an oxidative process going on. An oxidative process is a process that is going to use oxygen to break things down. So these are very important components within that organel or within that organ within that cell because those perryios are going to break down substances that may be harmful into harmless products inside the cell. However, what if those things went a little bit crazy? We had a little bit too much perryioism going on here inside the cell. Does it make sense that we would start having that oxidative process going on and maybe affecting good tissues as well as harmful tissues? This is why we take our antioxidants. So if you're taking vitamin C or vitamin E or you're drinking your green tea, eating your green leafy vegetables, you're taking antioxidants in in the diet for the purpose of trying to bind up the extra oxidative enzymes in the body. The mitochondria, this is going to be the area of the cell that is the energy source. So this is the energy source for the cell. You can think about it as kind of like the power plant of the cell that's producing all the energy that the cell is going to need in order to be able to function appropriately. So that's our mitochondria. Again, what could what would happen if we ended up not having a working mitochondria? We would not have enough energy to run the cell and then the cell would start to die. So all of these organels are just really important to maintaining that normal cellular structure. Okay. Okay. Now, the cytokeleton, this is going to be the muscle and bones part of the cell. In other words, it's going to maintain the cell's shape and internal organization. Yes, the cytoplasm gave the cell shape, but it could have been just some kind of random blob without having a cytokeleton. So, the cytokeleton is going to cause that cell to be round or to be oblong or to be whatever shape it needs to be in order to be able to have its normal functioning. the plasma membrane. This is the structure on the outside of the cell. In some cells, like bacterial cells, they have a cell membrane. Now, we don't have that. We don't have a cell, I'm sorry, a cell wall. We don't have a cell wall in human cells. We have a cell membrane or plasma membrane on the outside of the cell. And it's not just a wall. It's not just something covering or holding that cell together. It's a very active part of the cell. So there's a lot of stuff going on here in this plasma membrane. And that plasma membrane is going to control how much stuff is moving in and out of the cell. So what are the functions of that plasma membrane? Transporting nutrients and waste products in and out of the cell. So nutrients in, waste products out, right? Generating membrane potentials. A membrane potential is the potential of the membrane of that cell to be able to conduct electrical energy. So it conducts or it makes electrical energy. In the case of heart cells, it can make their own electrical energy and then they conduct that electrical energy from cell to cell so that the heart can contract. But that's what our membrane potential is. the potential to be able to maintain or generate an electrical energy so that we can have con conduction and contraction of electrical energy in the body. Cell recognition and communication. So that plasma membrane is going to tell the cells around it, hey, you know, we're all part of the liver here, okay? We're all the same here. We're all part of the liver. And that's the way the body is going to know that that is a normal healthy body cell versus that cell maybe being a cancer cell or a bacterium. So when things get into the body hopefully the body is going to recognize that abnormal thing this the bacteria the virus the you know whatever and it's going to destroy it. The way the body is able to do that and not destroy the healthy functioning cells in the body is by the plasma membrane. The plasma membrane has cell recognition and communication. So let's do the recognition part first or I think we did but let's talk a little bit about communication. So then the outside of the cell can also communicate with other cells that are part of that organ. So again let's go back to the heart because that's probably I think an easy example of how we have communication between cells. In the heart we'll generate a membrane potential in one cell then gets communicated to the next cell. So our electrical energy moves across that heart wall. All right. Other kinds of communication that cells can have well they can communicate within themselves to stimulate an organ. For example, maybe the pancreas is going to stimulate itself to release some extra insulin. So we can have an auto stimulation of the cell, an autoregulation of the cell growth regulation. So the plasma membrane is also going to say, "Hey, okay, this is as big as we get. We don't get any bigger." This way we don't have different size cells. Maybe one cell in the uh liver decided to get really really big and that's going to impair the function of the liver. If one cell's really big and the rest of the cells are really small, we're not going to have the same kind of function we would have as if we had a whole bunch of nicesized cell. So the plasma membrane is going to say, "Hey, this is where we cut it off. Enough growth. Let's move on." There's also sensing signals that will enable the cell to respond and adapt to changes in the environment. Okay. Now, we're not necessarily I mean in some cases, yeah, we may be talking about the external environment. So, most of us when we think of the environment, we're thinking of oh, let's you know, green trees, hug a tree, you know, we're thinking about that kind of stuff in the environment. We're not talking about that here. What we're talking about here is we're talking about the body environment. Sure, changes in temperature outside the body could be sensed by the skin. And the skin is made up of cells. So, yes, we could say that that's part of that. But what we're more talking about here when we talk about cells in the bodies, we're talking about the internal environment. So we have a change in the internal environment. Maybe there's a change in the pH in the acidic nature of the body and that's going to cause the cell to be able to adapt and respond. Okay? So it's not just I mean certainly there are cells on the outside of the body like in the mucosa and in the skin etc that could be sensing the external environment but we're talking also about those sensing capabilities of cells inside the body. Now the plasma membrane also has this capability of this uh the idea that we call the fluid mosaic model which is that the plasma membrane can determine what kind of stuff comes in and what kind of stuff goes out. So it's semi-p permeable which means that some things will be impermeable. Some things cannot go in and out and then something for example what about the internal the organels? We wouldn't want the organels just kind of randomly going in and out of the cell. All right. So the plasma membrane is going to hold the organels in in the same by the same token those the plasma membrane is also going to keep stuff out that should not be inside the cell. So there's some flexibility to it. It's self-regulating. It's going to be impermeable to some substances. So they can't get inside the cell and cause damage and cause problems to occur. But there's also going to be some changes in how this fluid mosaic model works depending upon the amount of cholesterol in the body and depending upon the temperature. Oh, there's cholesterol. We're going to hear a lot more about cholesterol throughout your nursing career. Cholesterol, that bad guy, keeps coming back up over and over again. So, here's a picture of what the plasma membrane might look like. And some of the components are involved here. So, you see lots of different things going on here. We have the phospholipid billayer. We have these membrane channel proteins. We have cholesterol. We have uh all sorts of different components here of this membrane. And all these different components are helping to regulate what goes in and what goes out of the cell. So let's take a look at some of the different mechanisms by which substances can move in and out of the cell. First of all, there can be a transport channel. So that's what is showing in the upper left hand corner here is a transport channel which means we have a specific channel inside that plasma membrane that is designed to transport one specific kind of substance. So maybe that substance is potassium. So we have a potassium channel that allows just potassium to come in and it's going to keep everything else out there at bay. It's only allowed to let that one kind of thing in. The next thing we could have that could be moving substances in and out would be an enzyme. Particular enzyme comes and it attaches to this little uh this receptor on that channel and that enzyme is then going to help that molecule to be able to get into the cell. We can also have a cell surface receptor, which means we have a little receptor on a surface of the cell that is going to stimulate this particular channel to either open up or close. So maybe that cell surface receptor is saying coming by and saying, "Hey, knock it off. Don't excrete any more of this particular substance that you're excreting." We can have self-s surface markers that are going to mark that cell, mark that channel for other types of substances that may be coming by and hopefully picking those up as it comes by. We can also have cell adhesion. One cell is going to be kind of combining or hooking up with another cell in order to provide some structure. We want to have those liver cells kind of have some cell adhesion going on there and being combining up here so that they're going to hold the liver together. I mean, you know, just imagine how bad that would be if the liver cells were just kind of floating around the body. Have one liver cell up in your brain and one in your foot, you know, I mean, it wouldn't be a very good liver working that way. We can also have that attachment. We can have an attachment from the the plasma membrane to the cytokeleton. In other words, two structures in the body holding that tissue in place. And in fact, we're going to see that in many cases that we are having our organs attached in place so they're not just flopping around inside the body. So some of the functions of the plasma membrane include endoccytosis and exocytosis. Endoccytosis means we are ingesting, we're bringing things in. Endo means in. So we're bringing things into the cell. Exo means out. So we're taking things out of the cell. So we're bringing things into the cell. We're ingesting liquids and molecules. We're bringing them into the cell. And then by exocytosis, we are having cellular secretion. That ex that secretion could be excretion of waste products. It can also be secretion of certain substances that are used in the body. Maybe this particular cell is a pancreatic cell and it's going to secrete insulin. we could have our cells combined up and connect together causing cellto cell adhesions. Now this is very important in order to be able to provide structure inside the patient's body. So this is kind of a busy picture here showing a lot of stuff going on here. Over on the left hand side we have the basic structures that are putting together our tissues. So we have the endothelium which is certain kind of cells endothelial cells are going to be combining. are going to connect to this basement membrane by way of using integrans. So they're are going to combine together there. They're going to hook up and they're going to start to form a tissue. Now you can see what's happening here is we're forming that tissue of the capillary. If we were to blow that up a little bit, we can see that there's a whole bunch of stuff going on here in the basement membrane that's holding that together. Then we have this interstitial matrix. The interstitial matrix is the matrix that is holding our tissues together on kind of a more global level. So, lots of lots of stuff going on here at the cellular level, but that's what's causing us to generate some structure in the body. When cells bind up together, we're going to have this junctional complex that's occurring here. So, what's showing here at the top is we're going to see we've got this junction. And we've have these junction of these two cells binding up together at the top there. Those are epithelial cells. And in this case, they're binding up with something called a belt decim. So this belt decesimone is going to be holding like a belt holding our cells together. We also have spot decimones which are kind of like sticky tape on the side of that cell holding the cell together. So you can see there's a lot of different components here holding these cells together. And what is showing down there at the bottom is a tight junction. A tight junction is one of these belt decimals who are combining together and holding those two components together. So you can see it's almost like it's glued those two cells together. Now, one cell needs to be able to communicate with another cell so that we can tell our body parts what to do. So, I mean, even something as simple as being able to lift your hand up off the table and being able to take your heel and hit your forehead and say, "Oh, I I knew this already." Okay. Well, even something as simple as that is going to involve having a lot of cellular communication between one cell of your body and another cell of your body. So, we need to have this communication occur. Now, there's also different kinds of communication that are going to occur. So let's take a look at each one of those because it's not just a matter of moving your skeletal muscle and saying I already knew this. But it's also a matter of being able to communicate between different cells in the body so that we can run functions that you don't even think about like our hormonal functions in the body and digestion and things like that. So our plasma membrane has receptors bound to it. There's also intracellular receptors. So inside the cell there's receptors. There's also gap junctions. These are on the outside of the cell between cells that are going to have contact signaling. So, we're going to have it's kind of like having two contacts rubbing up against each other. You put a battery into a flashlight and screw the top on and the contact in the top of the flashlight contacts the contact of the battery and now we have a contact signaling of electricity. Same kind of thing. These two cells rubbing up against each other are going to be able to contact each other and signal between each other. We can have chemical signaling in the body and there's a number of different varieties of methods here. We're going to take a look at those in a minute. And then we can also have neurotransmitters. So let's take a look at some of those in a little bit more depth so we have a better feel for how we're getting some of this communication in the body. So here is a contact dependent type of communication on the upper left hand side here. So the two cells are actually touching each other and one cell can communicate to the other cell because they are touching. Now again I mentioned this a little bit earlier as maybe one of the modes by which one of the parts of the body where this would happen is in the heart cells. One heart cells communicating electrical energy to the next heart cell so that they both can contract. The next type over there in the middle at the top is paracrine. Paracrine is a secretreting cell is going to secrete hormones that are going to activate or they're going to have some effect on target cells that are adjacent to that secretreting cell. So para meaning next to and it's going to be secretreting hormones that are next to to cells to activate cells next to it. Autocrine is a situation where the cell is secretreting hormones that are going to target itself. it's going to stimulate itself. Okay, so that's autocrine. It's like a self-motivator, right? Hormonal stimulation. Here we have a cell that is releasing a hormone, but the hormone then has to go through the bloodstream to get to its target cell. Okay, you see how that's different than paracrine? Hormonal, we are releasing the hormones into the bloodstream. They travel throughout the bloodstream and have their effect on some other target cell. So let's say for example the thyroid is going to release thyroid hormone into the bloodstream and then stimulate the cells the muscular cells of the body that are going to increase our metabolism as we exercise. Okay, that's going to be a hormonal stimulation. Paracrine on the other hand is going to be a simul a stimula try one more time. It's going to be a situation where the secretreting cell is going to be secretreting its hormone and targeting cells that are adjacent to it. Neuro hormone secretion. Now you see over here we have the neuron. Maybe that's a brain cell. We have a neuron that is secretreting the hormone into the bloodstream and then the neuro hormone goes to the target cell and it's going to stimulate that target cell. Okay. Okay. So, let's say a situation for that fight orflight response. In the fight orflight response, your brain recognizes the fact that you're in a situation. It's a fight orflight situation. And the brain is going to say, "Okay, let's get out of here." And it releases epinephrine and norepinephrine. Those hormones get into the bloodstream. They go down to target cells and they make your heart rate increase. They cause your vascule to constrict and they're going to release more glucose from the liver and get your muscles moving so you can get out of there. We've all heard those stories of the 90-year-old woman who lifts up a car to save a baby that's stuck underneath a car and things like that. Okay, that's caused by having this big release, this fight orflight response, the big release of epinephrine and norepinephrine. And that's an example of neuro hormone secretion. Lastly, we have the neurotransmitter. neurotransmitters are going to release their neurotransmitter, their hormone, and target a cell that is adjacent. So, we have that neuron, that nerve cell that is going to target an adjacent cell. Now, that doesn't have to be in the brain. That adjacent cell could be out in the periphery. Okay? We have nerve cells throughout the body. So that could be something that's localized somewhere else in the body, but uh it's going to be an adjacent cell rather than a global kind of a situation like the neuro hormone secretion. So we're moving our signals, we're moving our communication from cell to cell in the body by a number of different ways. One way is by using these extracellular messengers called lians. We can have channel regulation and second messengers that are being used in order to be able to contact other cells and to tell them what they're supposed to be doing. Also, taking a look at this picture here over on the left hand side, what's marked as being letter A, we have an extracellular signal molecule coming in and it's attaching here to a receptor site on that plasma pro that plasma membrane. then that's causing some kind of intracellular signal to occur inside the cell. So it's not the same thing that that extracellular signal molecule doesn't just get transferred or moved inside the cell. It comes its signals then inside the cell there's a separate signal molecule that is going to whatever type of function needs to be done inside the cell. Over on the right hand side, what's listed as being I believe is letter B or letter C here is the signaling lian receptor. So we talked about the lian. So the lian there is that little pink thing, the pink ball at the top. It's coming to its receptor. Now what that's going to do is it's going to cause a number or a possibility of a number of different things happening inside the cell. First of all, it could just be re relaying information. So it's relaying information to the cell to tell the cell to do something. It could also be that inside the cell that message becomes amplified and then has some effect inside the cell. Or it could be that that particular signal becomes diverged into different regulation or different things occurring inside the cell. Down at the bottom here, I think what's listed as letter B, it's kind of hard to look at this diagram and figure that out. Okay, but what we have if you go across the top there, so we have our signal molecule and those signal molecules are going to that cell and telling it to survive. Okay, it did. Fantastic. All right, so let's go over to the next one over on the right. And we have those signal molecules coming, okay, that we have the same ones there telling the cell to survive, but we also have signal molecules coming to the cell telling it to differentiate. So now it differentiates into a different kind of cell. And we see that happening there. Down at the bottom, I guess this is now illustrated as being letter D. But down at the bottom here, what we have is the cell and it's being stimulated to grow and divide. And in fact, it does. It grows and it divides into two more cells. Or we have down at the bottom there the lack of the stimulation. So we have the lack of our signal signaling molecule. The signaling molecule is no longer targeting that cell. which tells that cell it's time to die. And there's a regular programmed method of cell death in the body and that's called apoptosis. Adenisonin triphosphate. Okay, you probably remember this from ATP. Adenisonin triphosphate. This is going to be the energy that the body runs on. So we need to be having we need to have enough ATP. We need to be making enough ATP in order to be able to carry out the functions that we need to have in our body. So ATP is really really important. We need to have that cellular energy. Cellular energy is important for digestion to be able to break down our proteins, our fats and our polysaccharides into subunits. It's important for glycolysis, the breaking down of glucose so that we can then use that glucose to make more energy. Glycolysis is a process that is going to be anorobic in nature and we can produce more glucose obviously by anorobic metabolism than we can through glycolysis. But glycolysis is one of the methods by which we can have a patient develop um energy and ATP in the body. Uh so there it is. The citric acidic cycle also called the Kreb cycle. Probably very familiar with this from anatomy and physiology. But this is where we produce the most ATP. So very important component here in the body. We have to be running the citric acid cycle, the KB cycle. In order to produce enough ATP to run the vital functions of the body. Now the body can live for a little while without producing as much. So we can use anorobic metabolism for a while, but that's not going to hold on forever. we need to have the citric acid KB cycle working. What happens in this cycle is we're going to have the process of oxidative phosphorilation and this is the process that's going to produce our energy from our metabolism of fats, carbohydrates and proteins. So let's take a look at this diagram here and the main component to know about this, the main thing to recognize and to really hang your hat on here is that we've got to know the difference between the top and the bottom. So you don't need to know all the details that are occurring here at every step in the process. Let's start at the top though and let's work our way down so that you can get an idea as to what's happening where and how this changes depending upon whether or not oxygen is present. So go up to the top. We have our food. The person ingests the food. We have proteins, polysaccharides, and fats. We're going to break those down. We're going to break the proteins down into amino acids. We're going to break the polysaccharides. We're going to break our carbohydrates down into simple sugars. and we're going to break our fats down into fatty acids. Okay, so the first part of our metabolism is being done here. In that carbohydrate metabolism, we can have some glycolysis go on here. In other words, breaking down glucose, which is going to produce some ATP. The result is that we're going to produce pyuvate and acetal COA. All right. Now, if we don't have oxygen present, we stop there. So the top part of this process here and then that pyuvate process right there is going to start to produce lactic acid and that's going to be a problem that we'll we'll talk about later. But we don't get down to this bottom section here without having oxygen present. So we make the acetto coa we go into the citric acid cycle. That's where we have to have oxygen present in order to be able to make this energy occur. So there's going to be much much much much more ATP produced during the process here of oxidative phospholation. You see where oxygen comes in here and then we're going to have enough energy to run the body. So if we were to break that down and say okay our patient did not uh get to that point. So here we are at the top here. We we did our digestion and we're at the pyuvate se section here. Now we're going down into producing these three different things here. the acceto COA which was what we want for our citric acid cycle but we're also producing lactic acid. Now if we're going down and we're moving through the center part and making acetto COA and going down into our citric acid cycle not such a big deal. However, if that part is not working because oxygen isn't present, then we move over to the right and we start making more lactic acid as a result of our non aerobic type of metabolism. And that's what's going to cause the patient to develop an acidosis. And we also won't be producing a whole lot of uh ATP because we're not running through that citric acid cycle. In addition to holding the cell together and keeping things where they belong, our membrane can also transport things in and out. We can take in nutrients, we can take in fluid, we can take in chemical messengers, we can excrete metabolites. Okay? of the waste products products of metabolism are endroducts of losome digestion and okay so we're excreting our digestive waste products is what it's saying electrolytes are very important to the function of our cells but we don't just want a whole bunch of electrolytes to come flooding into the cell that might cause some problems we can't have a whole bunch of sodium or a whole bunch of chloride or a whole bunch of potassium potassium running in and out of the cell. We need to have a balance. Obviously, your body has a balance of electrolytes at any time. And if you take in too much, so let's say for example uh you decided, hey boy, I really like these energy drinks or I really like these uh workout drinks they advertise on TV that sounds really good and you drink these and it's got all sorts of electrolytes in it and your body doesn't need it. Well, guess what your body does? You just excrete it. It gets excreted in urine and you don't even use it. Okay? So the body doesn't need it. You're not going to hang on to it. Two different kinds of electrolytes. We talk about them as being positively charged. We call those cations ions. Or negatively charged. We call those annions. Okay. One thing that helps me to remember the difference between the cations ions and annions is an like a being without or whatever. A n negative. So that helps me. I don't know if it's, you know, maybe it helps you to to remember it a different way or whatever, but annions are negatively charged and we got the N in the word uh at the beginning of the word at least. And that helped me to remember that's negative. Electrolytes are going to be measured either in mill equivalents per liter or in mill per deciliter. So you're going to see two different ways of measuring this when you look at patients charts. For example, if we're looking at somebody's potassium level, it's going to say the potassium level is 4.8 8 mill equivalents per liter. If we're looking at somebody's blood glucose level, it's going to say the patient's blood glucose is 102 mg per deciliter. But uh those are just two different units of measurement that we use when we're measuring electrolytes. We're not going to get into why. I mean, it's a whole chemical and chemistry thing or whatever. So, you don't need to really worry about that a whole lot. You don't really need to worry a whole lot about what's going on here with these different charges, etc. Just understand that some of our electrolytes have one charge such as sodium. It's got one positive charge. Some of them have two charges such as calcium. Calcium has two positive charges in our body fluid compartments. We have an intracellular compartment that's inside the cell. Extra or I should say intravascular compartment that's inside the vessels, blood vessels. And then we have an intra or interstitial compartment. So we have three different compartments inside the cell, inside the blood vessel, and then pretty much the rest of the tissue. Each one of these different areas is going to have its own balance of electrolytes. So the blood vessel may contain more electrolyte than the tissue does or the blood vessel may contain less electrolyte than the tissue does. It's going to maintain its balance by these positive and negative charges that are on the electrolytes. One equivalent of any cation. Okay, cation is positively charged or negatively charged. Okay, if you said positive, you're right. Can combine chemically with one mill equivalent of any annion. So then an annion must be negatively charged, right? So one positive charge, one negative charge. Okay, they neutralize each other. So, we're going to have to try to find something that's going to neutralize so we don't have these elements, these electrolytes running around in the body with this positive charge. So, for example, calcium. Calcium might combine up with a couple chlorides and then we have calcium chloride. There's a couple different ways that we can have body fluids move around. Body fluids and electrolytes can move across our cell membranes. either be a passive mechanism, so there's no energy required, or an active mechanism. A good example of an active mechanism is our sodium potassium pump. Passive transport. Okay, so there's no energy needed here. We don't need any ATP to run this. There's just a diffusion. So solutes just kind of diffuse across that membrane. There may be some filtration. Okay, different processes going on here. Diffusion is just a passive process by which fluid and electrolytes move through a filter. Just think of like a maybe a coffee filter. It's just passive. It's just the fluid is running through it. Some of that coffee is running through it. Uh we can have filtration. And I don't want you to get confused here because I was just talking about a coffee filter. Filtration is caused by hydrostatic pressure. Hydrostatic pressure is the pressure in the blood vessel. The higher the pressure, the more fluid that gets pushed out. The lower the pressure, the less fluid and electrolytes that get pushed out. So hydrostatic pressure is pressure inside the blood vessel pushing fluid out. Okay. Now remember with diffusion we didn't need to have pressure. We didn't need to have anything else. Diffusion was just fluid moving. It's just moving across that membrane. Doesn't need any help. Okay. Now we have osmosis and osmotic pressure. With osmosis or osmotic pressure, fluid is going to move from when there is less electrolyte to where there is more electrolyte to try to balance out the amount of electrolyte. So let's say that we have half of our class. We split the class in half. We've got 12 people in our class. We've got six h six in each half. All right. Well, instead of just splitting them evenly, let's say that instead we take eight people on one half and four people on the other half. That's going to look uneven, right? So, the natural tendency is for some of those people to go over to the other section. So, we have an even split of six and six. That's what osmosis is like. Osmosis is water moving to where there is a greater concentration in order to dilute that concentration so that the concentration will be the same on both sides of the membrane. This is controlled by a concept called osmalerity or osmolality. This is not something that you're going to need to differentiate in your clinical practice. Okay. So whenever you think that the term osmalerity osmolity think of concentration. So the concentration of water tenicity re this is a concept that is talking about osmalerity and osmolality. We're going to get into that a little bit more a little later but we can have solutions that are either going to be very concentrated or they're going to be normal concentrated or they're going to have a lower concentration and that will affect how fluid moves. We can also have a process that's called passive mediated transport. So, this does not involve energy, but it does involve having specific proteins or specific channels that are going to allow that substance, usually an electrolyte, to pass into the cell. So, in this case, what we have going on here is we have a protein transporter and a protein transporter is even moving the solute into the cell. That's what we see here over on the left hand side with uniport or we could be exchanging. We're moving the solute into the cell and we're also moving another solute in. So it won't move in without that other solute. So that's what we're seeing with Simport is we're seeing two molecules move into the cell at the same time because one won't move without the other. Over on the right hand side, what we see is anaport. We're moving the substance into the cell. But in order to do that, we have to move something else out of the cell. So there has to be an exchange. One goes in, one goes out. Active mediated transport is a process by which there is going to be some energy expended. A good example of this might be our sodium potassium pump. Sodium potassium pump is pumping sodium and potassium in and out of the cell in order to maintain a good balance inside the cell. We can also have endoccytosis caused by vesicle formation and our vesicles are moving things moving substances into the cell or we can have exocytosis where we're moving waste products out of the cell by an active mediated process. So this diagram here is illustrating our sodium potassium pump. So we have our sodium potassium pump and actually I think the diagram here is it's kind of confusing maybe a little bit. It looks like it's starting at the bottom here. So we have our ATP coming to the sodium potassium pump and we are moving our sodium outside of the cell and potassium starts moving out of the cell as we move over to the picture on the right there at the bottom and then we move up to the picture at the top left. I'm sorry. We move over to the left and the picture at the top left. We have our sodium potassium ATPAS is coming to our sodium potassium pump and that's going to activate the pump. So ATP is going to activate the pump and pump sodium out. All right. Potassium is going to come in in its place. I guess it does start at the top left. So sodium is being pumped out on the top left there by using ATP. ATP has to activate this. Then potassium comes in through the channel on the right. See the potassium coming into the cell. And then we're going to have that exchange of sodium for potassium. So we're going to have an unequal amount of sodium potassium on either sides of that cell membrane as a result of using that sodium potassium pump. This is showing the process here by which we have endoccytosis. So we have this particle coming to the cell membrane. in the cell membranes are able to cause a membrane bound vesicle to bring that particle into the cell and then that vesicle is going to be digested by our lo. Uh then we can have the waste products of that digestion excreted through a membranebound vesicle to have exoccytosis for those waste products. In addition, our membrane, our plasma membrane can have a resting potential and cause an electrical impulse to be generated. Now, certainly you've seen on TV where they have the pictures of the EKG complexes and they have somebody hooked up to an EKG machine and you're hearing that beep beep beep of the EKG machine. Well, this is what we're reading here is the electrical impulse that were generated by the heart cells. So, they generate first of all a resting membrane potential. This is important because the resting membrane potential is what's going to allow that cell to be able to create an electrical energy. Without that resting membrane potential, it does nothing. It's just flat. It's just sitting there. It's got no electrical energy going on there. Okay? But we need a little resting membrane potential is what creates the possibility for that cell to be able to become electrically charged. Then we have the action potential itself. If the action potential is going to be characterized by a depolarization, then we reach a threshold potential which is a hyperpolarization. Then we go into repolarization which is kind of like reloading and then we have a refractory period. So let's take a look at this a little bit more here. Uh what this is showing here on the over on the left hand side is the movement of sodium potassium inside of the out of the cell. So in other words, this is happening by way of an active pump, an active transport pump which is causing the movement of sodium potassium in and out. Okay, looking over on the right hand side, we see we have hooked up this cell to this EKG machine, which is going to determine how much electrical energy is being generated by the cell. So we have a resting membrane potential, which means there's more charge on one side of the membrane than the other. Okay, so there's more charge on one side of the membrane than the other. And that's what gives it an electrical capability. If the electrical energy is the same on both sides of that cell, the plasma membrane, then there will not be the capability of having an electrical discharge. Now we move into the middle picture. Now we're starting to get depolarization. Notice what's happening there. Those positively charged sodiums on the outside of that cell are rushing into the cell. Now there's more positive charge inside the cell than there is outside the cell. See how that changed. Picture at the top of the page, more positive charge on the outside of the cell. The middle of the page, more positive charge inside the cell. And that's what's called depolarization. Okay. Now, we want to get that cell back to its normal resting state so it can depolarize again. In a heart muscle cell, when we see deolarization, what happens is the heart muscle contracts. So now, we can't have it just sit there contracting all day long. It needs to relax and be ready for the next contraction. Right? So now we move into repolarization. And you see what's happening there at the bottom. We're pushing potassiums out so that we can rapidly get that cell back to a state where there's more positive charge on the outside of the cell than there is on the inside of the cell. Okay. Okay. Now, what's going to happen eventually? That sodium potassium pump's going to pump those potassiums back in the cell and the sodiums back out of the cell. But initially, what happens is the potassiums rush out in order to cause that repolarization in order to cause that positive charge on the outside of the cell. Just a couple words here about the process of cells dividing and can be turning into a couple different cells. We're going to talk a little bit more about this when we talk about genetics. Uh but in this case here, just very basically take a look at the diagram here and get a feel for what's happening as this cell is starting to divide. [Music] [Applause] [Music] So what you see going on here is we see that there's the genetic material being kind of pulled apart into two separate entities. so that we have two separate entities of genetic material available for these two new cells that are going to be formed. And again, we'll get into more detail with that later. So, we have different types of tissue that are going to be formed in the body. One type of tissue, a very common type of tissue that we see throughout the body, very important type of tissue is our epithelial tissue. It is going to be the lining tissue of most of the organs of the body. We can differentiate our tissue as either being simple or stratified squamus types of epithelial tissue. There's also transitional cubuidal simple or stratified colmer or pseudoratified siliated epithelial tissue. So you can see there's a lot of different kinds of epithelial tissue in the body. Kind of makes sense, doesn't it? Okay, we got a lot of different kinds of tissue in the body. So this is showing a picture here, a microscope picture here of the stratified transitional epithelial cells on the right hand side, our connective tissue at the bottom, the basement membrane that's combining the two of those things together so that we can form different kinds of tissue in the body. But epithelial tissue is the underlying base tissue that is forming the inside lining of most of our organs and tissues in the body. Connective tissue on the other hand is going to be tissue that is connecting as the name implies, right? Connecting two things together. It can be either defined as being regular or irregular. Uh there's going to be fibers that are going to connect one tissue to the next. It's going to have this elastic reticular connective kind of a component to it. And this is going to be the thing that's going to make up cartilage, our bone, our vascule, and our atapost tissues. So those are all going to be types of connective tissue. Muscle tissue can also be divided down into three major categories being smooth muscle, styate. Yeah, let's try that again. Striated which is skeletal muscle and cardiac muscle. So three main types of tissue here or muscle tissue in the body is smooth muscle. The smooth muscle tissue is going to be the muscle tissue in your heart and your other autonomic functions of the body. So the GI tract etc. That's smooth muscle. Smooth muscle does not need voluntary control. In other words, you don't have to wake up in the morning and say, "Okay, heart beat. Okay. Uh intestines, let's digest right now." Okay? You don't have to tell it what to do. It's autonomic. It's going to just run on its own. Skeletal muscle, on the other hand, for the most part, you need to tell it what to what to do. Now, we don't always think about the things we're doing. So, let's say that you slip on a little patch of ice. You're not thinking, "Oh my gosh, there's ice. I need to catch myself before I fall." Okay, that happens automatically. That's a reflex. So, we have reflex nerves that are going to be detecting what's going on and sending out impulses to those muscle fibers. That's not the same as what's happening with smooth muscle. Smooth muscle is generating its own information or it's getting its own information on a continuous basis. So it doesn't have to be told that okay time for the heart to start beating. It's doing this all the time on a regular basis as opposed to skeletal muscle which always has to be stimulated from somewhere either from a conscious thought or it's going to have to be stimulated from some other kind of nerve activity. Cardiac muscle is being defined separately from smooth muscle in this example here because cardiac muscle not only is going to be able to do its thing on its own. you know, it doesn't need to have a conscious voluntary action to be able to make it beat. But cardiac muscle also has the ability to generate and conduct electricity, which other muscle fibers in the body may not have the ability to do. Well, thank you for joining me for Cellular Biology. My name is David Woodruff, and until next time, bye now. [Music]