Anatomy & Physiology 1 - Lecture 2 | Chemistry (Atoms, Water, Polarity, Macromolecules, pH)

All right, everybody. So, on to lecture two for anatomy and physiology 1. And today, as you look through the topics, you'll recognize that word chemistry and atoms and molecules, but we're going to make it understandable in this lecture. You see, I'm only going to go through the basic chemistry that you need to know specifically for this course. I'm not going to get into the weeds and all the details of things that you don't Necessarily need to know for amp to be a good nurse, etc. But before we explain all of those things, I want to

just have a little experiment for you. And I would like you to choose pill number one or pill number two. These are two different molecules, right? So molecules are just multiple atoms like carbon and hydrogen and oxygen bound together in one cool structure like all these lines are just representing carbons and hydrogens. And these are pretty big molecules. Now You'll notice between the two that there is one difference. See if you can find the one difference between these two very very very different molecules. Okay, so hopefully you notice that it's this little O group right

here, right? It's a hydroxal group with an oxygen and a hydrogen bond. And that is the one difference between this molecule and this molecule. So again, take your pick, write it down on your paper, and we'll see where we get later on. All right, so First off, why do we need to know chemistry? What's the point? Well, did you know that we live in a physical world, right? Where there's matter, there's stuff, there's atoms, and there's interactions and forces going on all the time. And we need to understand how those forces work in order to

understand everything else. So, the base science essentially for all science is physics, which is basically how forces interact and starting to talk about how Matter interacts with those forces. But then we need a way to understand how this works. We need to understand the forces. We need to understand the math behind it. So therefore, we formulated math, another science in a way. That's why math and science are so tightly related because math basically describes physics, right? How much force is there? That is a numerical value, right? But not only that, we can then take math

and apply it to how atoms interact, which is Chemistry. So chemistry is just atoms and their interactions, how they move about, how they form bonds and break bonds, how they connect. So physics informs math, math informs chemistry, and then chemistry informs biology. We know that living things are constantly doing metabolism. These chemical reactions to help keep them alive. That's basically all metabolism is just all the chemical reactions happening in them. So chemistry informs how life Biology bio meaning lifeologist means the study of how life works. But not only that, biology informs anatomy and physiology. Why?

Because we are human beings. We are living creatures. So, in order to understand anatomy and physiology, we need to have a great grasp of biology, don't we? How life works. But not only that, we need a good grasp on how chemistry works because we're made of atoms and their interactions. We need to Know how chemistry works. Uh-oh. Which means we need to know math, which means we need to know physics. So, what I always argue is that&p is one of the hardest disciplines because we need to know all of these things in order to understand

it properly. But you saw that in lecture one already. I talked about uh things in nature like to flow from high to low. You know what that is? That's physics actually informing chemistry. Physics, the force of Basically high concentrations of things moving to low concentrations of things. So we've already kind of implied some of these disciplines while we've been talking about A&P, which is kind of cool. So don't get scared. These are not scary topics, although they might be from past experiences in your life. But what I'm going to do is pick and choose the

bits of these things that you need to know for this course to be successful. So, not only is chemistry Atoms and interactions really important for A&P, but we also know that structure fits function because in chemistry the structure of the molecule informs what it's going to do and different structures will have different functions. So as an example, if you selected this molecule, this molecule to take, you actually just took a molecule called sseudafed. This is a helpful medicine to sometimes help you get over a sickness, maybe like A respiratory illness. But if you decided to

take this one, you actually just took methamphetamine, which will ruin your body and ruin your life. What's the difference? two atoms, two atoms of a difference makes the function that drastically different. You either cured your cold or you ruined your life. So don't tell me chemistry doesn't matter because you need to know how these guys interact in order to understand how they will act in Your body because different structures will have different functions. All right, please do not tell anybody. I just taught you that. But that was the first thing my organic chemistry professor taught

me in class and I thought it's a great way to engage students. So today, let's talk about why chemistry matters. Haha, pun intended, because matter is just simply anything that has mass and takes up space. So let's define that real quick. I don't Like definitions typically, but some I do. So matter, what is it? Matter is simply anything that has mass. anything. I like just when we say anything, just anything that has mass. So, has mass? It basically takes up space and takes up space. All right. So, if you look around in my room right

now, this whiteboard, is this matter? Is it made of matter? Absolutely. Am I made of matter? Yes, I'm taking up space. I have Mass. Does the air does the air take up space and have mass? certainly does. Now you'll see a commonality between all these things. We are all made of atoms. Matter is made of atoms. So we say that atoms are the building blocks of matter. Atoms are the building blocks of matter. In the same way we can say like cells are the building blocks essentially of living things. But even cells themselves are made

of many atoms. So atoms are basically the smallest unit We can zoom into in your body and we can find them and see hey how are they interacting? What does a carbon do? What does an oxygen do? What's different about them? All right. So we need to understand what atoms are obviously in order to understand how the body works. So what I'm going to be continually doing, I'm going to look at my student learning objectives, make sure I'm covering everything. Uh, so I'm going to be talking about first the three states Of matter. And this

is actually pretty important for A&P and how the human body relates to each because any type of matter typically comes in one of three forms unless you're into weird uh chemistry stuff. You might have a fourth form like plasma. It's kind of weird. But we know that there are three main states of matter. We know that there are solids. We know that there are liquids. And we know that there are gases. And I never know if gas has two S's in the Middle or one. So please check me on that solids, liquids and gases. Now

when we think about the states of matter like water as an example, you can have water vapor. We can have water as a liquid and then we can have ice as the solid. Yes. But what are we working with in a&p most of the time? Well, we know that your body is made of 65% water. Yes. And so therefore, the majority of our body is going to be operating in some sort of liquid Environment. And so we're going to look at how those molecules when they get into water, how they interact. So we'll see that

a lot later on talking about water and polarity. But we're also going to have some interaction with gases. You probably know that a very important gas in the atmosphere is oxygen. It's about 21% of the atmosphere and that is a requirement to keep us alive. We can't survive more than about 2 minutes without oxygen in our blood feeding our Cells. So, we'll also put off some gas called CO2. We'll talk about later on. Carbon dioxide. Your cells are basically these smoke stacks making a bunch of CO2, dumping it in your blood, and we've got to

get that out. So, we breathe out CO2. So typically we're going to be talking about these two states of matter as we go through this course because physiologically physiology and function typically functions best when we're talking about A liquid state especially. So I'm going to mention that a lot as we go forward. So now back to atoms or building blocks. This may be a review for you. If it is awesome stick with me and if not hey we're going to learn something new. So, at this point, hopefully you're realizing that chemistry and physics, they're not

so scary. So, go ahead and comment, "Chemistry ain't so scary." I would really appreciate that. I just love to see all the comments saying, "Chemistry ain't so scary." All right, so let's talk about atoms and their structure. I'm going to show you a very basic atom. And once again, I'm going to only teach you the stuff you need to know for A&P. First off, in the center of an atom, there are subatomic particles, basically smaller than an atom particles that'll be positively charged, positive one charge, and these are going to be called protons. Once you

know that Protons are a positive one charge. So therefore, every time you have a proton, you add one positive charge. That'll be important here in a second. You'll also have inside of this section of the atom other subatomic particles called neutrons. And I'm going to put a zero in them because neutrons have a neutral charge. So they don't contribute any charge to the atom. Neutral charge. So basically zero. So we this is actually the last time I'm Going to mention neutron in this class because they're not very important physiologically. So inside here we got protons

kind of squished together with neutrons. And we call this structure of both protons and neutrons. We call it the nucleus. Nucleus is just a fancy term that means center of something, right? So we'll see later on on a different level of organization. We have cells with the nucleus in the center. That's an organel of the cell. It's Still called the nucleus because it's kind of in the center of the cell. So we call this the nucleus because it's going to be in the center of the atom. But probably my favorite subatomic particle, the last one,

the third one is going to be your electrons. So draw an electron far out from the nucleus, a little smaller, a lot smaller actually. And these are again electrons. You can see that I put a negative in there. And the electrons are a -1 charge. -1 charge. So you notice if this is the atom itself, and we'll see what's happening here in a second. What is the total charge of this atom? Well, we know there's a positive one charge, negative one charge that is zero. So, typically atoms exist in a neutral form where they don't

have a charge. We'll see later on there are some circumstances where they actually turn into a positive or negative charge depending on the atom. Okay? So, atoms Are typically neutral. However, most important thing to catch with atoms, these electrons are not just standing still. These electrons are flying, orbiting at rapid speed around the nucleus. They're moving so so so fast that they basically make this cloud. It's called the electron cloud. And it looks like basically it's a solid object because they're moving so fast. That's a fascinating thing. We're not going to talk about a whole

lot. But what I want You to recognize is that they're moving so fast that they never crash into the nucleus. Well, Mr. J, why would they cra why would the electrons crash into the nucleus in the first place? Uh, well, if you've ever like heard weird dating shows, they have this cliche that where they say, uh, opposites attract. Have you heard of that before? Opposites attract. Like this type of person is opposite of this Type of person, so therefore they attract each other. Well, that may or may not be true in relationships, but in physics,

when we're talking about charges in electricity, opposites do attract. I want you to write that here. Opposites attract. That is so important to understand. Opposites attract. In other words, there's a force basically wanting both of them to come together. So, the electrons really have A force that's pulling them towards that nucleus. The nucleus is so big, it's so massive compared to the electron that it doesn't really have a pull towards the electron, but they do kind of attract each other. Very similar to how we are attracted to the earth because of the gravity of the

earth. So the earth is pulling us towards itself. So same thing here, but the electrons are moving so fast. This is kind of a fascinating uh subject. They're moving so fast, so much Kinetic energy that instead of moving towards the nucleus, they kind of form this circle. So that's what's happening inside of an atom. Pretty cool. If you have any questions so far, go ahead and drop them in the comments below. Um, and we can continue on talking about atoms because we know that atoms are designated based on how many protons they have, how many

protons they have. So, the proton number is also called the atomic number. Fun Fact, atomic number tells the type of atom. So, as an example, I'm not going to go through this uh too in detail, but when you have a one proton atom, this is actually an atom of hydrogen. We shorten up hydrogen just with that H. So, a hydrogen atom has one proton and one electron and actually usually doesn't even have a neutron. I'm just using this as an example. All right, so you got one proton, one electron, but the indicator Of what it

is is the proton number. All right. If I had two protons as an example, it would be helium. Um, and etc., etc., etc. But I don't really care about that stuff. Now, what I'm going to worry about is the electron. Okay? The electrons are the one moving a lot. The one the ones moving a lot. So, I want you to remember that electrons have the energy. Electrons have the energy. So, as we watch what electrons do, we will see how in a way energy is going to be Transferred. And energy is just the ability to

do anything. So as I am moving, I'm using energy. I'm harvesting energy in order to move. So let's move on and start talking about some of the atoms in the body that we will see as well as how electrons interact in that game. All right, so let me pause, look at my sheet real quick. We looked at the structure of the atom and now we're going to talk specifically about molecules in the human body. So let's Get rolling with that. I want you to write the following name. It's kind of sounds weird. It's called ch.

Ch. Ch or ch, however you want to say it. Ch. These are the five atoms that make up most of your body. So C is going to stand for carbon. We're going to have that guy a lot. H is going to stand for hydrogen as we just talked about. O is going to stand for oxygen atom. N is going to stand for nitrogen. And then P is going to stand for phosphorus. Okay, these are the most common atoms in your body, but we're also going to have other ones like sodium and chlorine and potassium and

others guys like that, but these make up most of your body. Now, that being said, when we form molecules with chonp, we can form a variety of different ones. So, as an example, we've got H2O. Yes, H2O, the most common molecule in our body is water. There are two hydrogens, H2 and just one oxygen. So, anytime there's no number outside of It, it's just going to say there's one. We can draw this guy and write water. H O H. That's a molecule of water. Now, you may be saying, "Okay, Mr. J, you just hopped from

an atom with protons, neutrons, electrons, and now you're just going to letters and lines. What the heck does this mean?" Well, what I want you to know here is anytime we have molecules with chon P with a C H O N or P inside of it, these atoms of these, right, are going to form things called Co-vealent bonds. Co-vealent bonds. What does that mean? Covealent bonds I'm going to write down here. So covealent bonds are when atoms share co- remember covealent bonds right co means like together they share electrons they share electrons what does that

mean well we know that oxygen has electrons we know that Hydrogens's have electrons and there's some interactions I'm not going to go through the details of them on how oxygen likes to share two different of its electrons and hydrogen actually likes to kind of share just one because remember hydrogen just has one electron. So what I like to remember this as and I don't have another person to demonstrate this but imagine like there's a person over here reaching out with their hand. This person is going to represent Hydrogen that hydrogen's reaching out with their hand

and oxygen's reaching out with their hand and they come together. All right, that's going to represent this covealent bond right here with that we'll go this hydrogen over here, right? Reaching out and grabbing that oxygen over there. That's a covealent bond. But what what are the what is what are these arms? These arms each arm individually is an electron. It's as if we're sharing each other's Arms so that this hydrogen almost has like two and this oxygen has two but there's only two arms in the bond but they're sharing them. So whatever we share we

basically hold both right. So what does that mean? I want you to draw this very specifically in every covealent bond. This is not the perfect way to draw but I think I I like it. Draw two red dots. Two red dots. So each line is a coalent bond and we got two red dots there. Every coalent bond Represents two shared electrons. Two shared electrons. So what if we have a new molecule? What if we have the molecule O2 oxygen? In that case, it's a cool little thing where that one oxygen atom is double bonded to

another oxygen atom. That's kind of cool. Well, how many electrons are represented here? Well, one coalent bond, two arms, two electrons. Another coalent bond, two Arms, two electrons. There are four electrons bonded between these oxygens. All right? So, all I want you to know is, hey, coalent bonds, they're when we share electrons between these five atoms. So, it could be the same thing with phosphorus and nitrogen like uh another one is like ammonia, NH3 or four. We'll do NH4. NH4, you got the nitrogen bond to a bunch of hydrogen. I'm not sure how many bonds

there are. I didn't prep this. I think it's actually Think it's this. But again, this is just representing, hey, there's electrons bond between hydrogen and nitrogen. Hydrogen, nitrogen, so forth and so on. All right? So, don't get overwhelmed by all of this. This is just a way to represent, hey, what's between the atoms and their electrons. Now, think about this. Think about this. If the electrons are between the atoms, what is stored here? What is stored here? What do you mean stored? What is Stored between these atoms in this case? Remember what the electrons are

doing? What are the electrons doing around the nucleus? They're flying so fast, right? And I said that the electrons have a lot of energy, right? So what's stored between these bonds? Energy. There's energy in a way harvested inside of those bonds. It's like holding itself together. There's so much energy because they're electrons. These arms are electrons and they're flying, flying, flying, moving, moving, moving. So a lot of energy is packed in between these bonds. All right? We'll see that a little later on when we talk about macroolelecules, especially like glucose. We'll see a lot of

bonds and there's going to be a lot of energy to harvest out of glucose. So we'll see that a little later on. So again, covealent bonds, we share electrons. It's the most common bond because these Are the most common atoms in the human body and it's just where two electrons are shared between atoms. All right. Now, that's not the only type of bond we need to understand. We also need to understand the bonds between what's called ions or ionic bonds. So let's briefly go through that and see how that relates specifically to A and P.

So on this side I'm going to write ionic bonds and this is going to represent the bonds formed When atoms transfer electrons. Transfer electrons. Now this is a different verb right? Transfer is different than share right? These are very different verbs. So very different bonds in this case. This is basically when an atom, imagine this is one atom with an electron that it really doesn't like. It's just like, oh man, I got an extra one of these. I don't really like this. I want to give it to Another atom who is actually like, I miss

I want one more electron and it wants to receive it. So, it's like a win-win, right? So, one great example is sodium and chlorine. Sodium and chlorine. You've probably heard of this one before for some reason or another. I'm not going to go through the details. It's called the octet rule. You can learn about it if you'd like to. For some reason, chlorine is in group number Seven and it wants one more electron to be more stable. It'll have eight electrons in its veence shell. It's called the octet rule. It really wants one more electron.

But the problem is sodium actually wants to give away one of its electrons. Okay? Okay, so sodium wants to give away one electron. Okay, reason being it's in group number one. It's got one extra veence electron Essentially and if it got rid of it, it would have a full outer shell, full octet. Uh don't worry about that for A&P, but just know that it wants to do that. So what sodium will do is when it encounters chlorine in a certain uh reaction, chemical reaction, bonding or breaking bonds, it's going to donate that chlorine its extra

electron. Okay, now here's the thing. What charge was sodium when it had that when it had that electron? What charge Was sodium? What charge was chlorine? What charge was carbon? What charge was hydrogen? What charge was oxygen? All of these atoms always what did I say? They are always neutral because their proton number typically equals their electron number. So right now sodium is neutral. Doesn't have a charge but it just gave away a negative. If you lose some negativity in your life you become a more positive person. Right? So when sodium which has a negative

one electron that it wants to give away donates that electron it's gone now sodium actually turns into a positive one charge. So sodium is now positively charged because it gave away one electron. One minus a negative 1 is positive one. But then chlorine was neutral too and it just received an electron a new electron. It was neutral beforehand, but now it just gained an electron. What Charge will chlorine be? Chlorine will be a negative one charge. Usually you see it written as one negative or you don't even have that one whenever it's a single. So

usually it's just like this. Whoops. So usually it's just sodium plus and then chlorine minus. It's typically what you'll see in any textbook. All right. Now sodium is now positive. Chlorine is now negative. What do you know? What's the rule? Opposite what's attract? Opposite Charges attract. And so therefore, sodium and chlorine form what's called an ionic bond. So sodium and chlorine are now budded together following that electron transfer because they're now opposite charges and they smush together. So now we have sodium chloride, table salt, right? You've heard of that before. Now, here's the thing. You

will never ever ever see this written in an A&P class. Instead, you will always see it written like this. Sodium plus chlorine minus. So, in other words, you'll always see them in their ionized form, which by the way, if you want this terminology, any positively charged ion is called a cat ion. Any negatively charged ion is called an anion. And I'm throwing around that term ion. It just means charged atom. So ion is a charged atom. Cat ion has a T. It looks like a plus. Positively charged. An ion has a Negative. Um so it's

going to be a negative charge. You'll always see them written like this. Why is that? You'll always see those written like this. And in fact, all of the ones that you will see written like that, things like calcium, things like potassium, things like chlorine, things like sodium. Let me write all these down. Chlorine, uh, sorry, sodium. Chlorine. Yeah, potassium is weird. It's that K. So that's Potassium. Sodium. Chlorine. You also see some magnesium a lot of the times. I think that's usually a just a plus. It might be a two plus. Um, what do you

notice? You may have heard that all of these guys are called electrolytes. Yes. Which literally translates to a separation or a breakage of charge. So there's kind of this this this charge difference somewhere. So what does that What does that mean? What does that mean? What are electrolytes? Well, we need to understand electrolytes and how they work based specifically on how water operates. because electrolytes are only present in fluid. Electrolytes are only present in fluid. And we're going to figure out why next. So now we get to a point in our lecture where we have

to talk about something called a polar molecule or polarity as well as nonpolar molecules. So let's break this Down over here. We're going to give some examples. So go ahead and write polar versus nonpolar. All right, these are kind of weird terms. It's like, okay, are we going to talk about Santa Claus here or not? But what are polar things or what is polarity? Well, polar molecules are molecules, okay? Molecules or atoms in some cases that have a separation of charge Within themselves. molecules that have a separation of charge, all right, within themselves. That's a

weird statement, weird definition. We'll get to it in a second. Then we've got non-polar molecules. If polar molecules are by definition molecules, so two or more atoms bond together. So sodium chloride, that was a molecule. We talked about water, H2O, these are molecules, just atoms bonded together, two or more. They have a Separation of charge if they're polar. What do you think non-polar definition would be? Well, it would be molecules that don't have a separation of charge, right? So, no separation of charge within the molecule within molecule. That's all we mean by that. Okay, what

do I mean by that? Well, let's do polar first because I just gave you some examples of those. We had sodium Chloride. So, we can write example. Example was sodium chloride. Why is sodium chloride a polar molecule? Well, how did this bond form? How did this sodium chloride form a bond? Well, we remember that sodium was a positive charge and chlorine was a negative charge and they still are. And opposites attracted, right? So, they came together and now they're neutral because there's a positive and a negative. So, they're neutral. But is sodium positive? Is Chlorine

negative? Yes. Therefore, is there a separation of a positive and negative charge in sodium chloride? Yes. Because that's the positive end, that's the negative end. So therefore, sodium chloride is a polar molecule. Does that make sense? So any ionic bonded molecule is polar. So any ionic compound or molecule is polar because by definition ionic bonds are when they have a negative or Positive charge and then they combine but they've got that separation. One's positive, one's negative. So therefore it's polar. All right? So that's easy. Ionic bond. Now I'm going to confuse you. Another example of

a polar molecule is water. H2O. Okay, Mr. J, I hate you already. I thought you said water was covealently bonded where we had our H here and it was coalently bonded to oxygen and also Coalently bonded to hydrogen. Yeah, that's water. I don't see a separation of charge there. It's not like oxygen is negative and hydrogen's positive. It's not like they formed ionic bonds. They form coalent bonds. They're sharing electrons. So, don't they don't they have an equal charge? No. Come over here. Water is a very interesting molecule. Why? Well, you've got to buckle up

here. I'm going to make this really simple, but you really need to listen to this next part. Look at water. What is inside of these bonds again? You could say a lot of things. You could say energy. There's potential energy. There's stored energy inside them. But why is there potential energy? It's because there are electrons. And the electrons have that energy. They're flying around like crazy. So those electrons, right, are shared between oxygen and hydrogen. But Oxygen is a little greedy. Oxygen is a little greedy for electrons. Have you ever had a kid, maybe you

have two kids in your family, and like one of them likes to hog things a lot more than the other? A little more greedy kid, right? So he hogs the toys close to himself. What's really interesting is oxygen right here is a very electro negative atom. Very electrogative. I know I'm throwing a lot of terms at you, but it Basically means it's going to be slightly negative because it has electrons closer to itself. So, what does that mean? Okay, so remember my analogy with the arms, right? These are electrons. Yes, this is hydrogen person over

here. Here's oxygen person over here. They share the electrons, right? There's two here. But what oxygen does over there is it pulls the arm slightly closer to itself. So now the electrons no longer equally shared. They're kind Of slightly hogged by oxygen. Does hydrogen still have it? Yes. But oxygen has them closer to itself. So what charge is an electron? An electron is one charge, right? So if there is this slight hogging I'm going to draw like an arrow hogging of these electrons closer to oxygen what oxygen becomes is slightly negative slightly negative I think

that's theta that's just a symbol representing it's a slight Negative charge it's a slight negative charge it's not full because they're sharing but it's a slight negative neative charge pulled a little closer to the oxygen. But wait, if oxygen's hogging those electrons, who's kind of losing out on some of that negative charge? The hydrogens's. So if oxygen's hogging some of the negative charge, hydrogens have a slight positive charge. Yeah. So this represents a slight positive charge Because they don't have the electrons close to them too much. So therefore come back to the definition. Is water

a polar molecule within this molecule. Is there a separation of charge? Yes. So water is a very polar molecule. And what's interesting is that water I'm going to move on to a new statement here. Water you write this water is The universal polar solvent. Solvent. Okay, now we're going to get into some details here, and I think this is where it's really going to apply and kind of break down where sodium chloride comes in here. So, solvent, what is a polar solvent? Well, a solvent is anything that dissolves. Anything that dissolves something. Okay. So, let's

just break it down from what you probably know. If you put say um I don't know sugar or salt in water and you mix it up, mix it up. Mix it up. What happens to the sugar or the salt or stuff? Well, it dissolves in water. Why? Because water is dissolving it. Okay. What does that mean? What does dissolve mean? Well, let's look at this. Let's say that we have water in a canister. I'm actually going to draw it out as a molecule. H O H and then H O H. So we've got a bunch

of water molecules here. Now one thing before we get into that I want to show you is that if the oxygen I'm just going to draw the negatives like this. If the oxygen are slightly negative and the hydrogens's are slightly positive, why did I draw the water molecules the way I did? Well, because if the hydrogen on one Water is slightly positive and the oxygen on the other water is slightly negative, what happens? There's a slight attraction here, right? Because opposites attract. This is called a hydrogen bond. Go ahead and write hydrogen bond. This is

a slight attraction, a slight pulling of one oxygen of one water and a hydrogen of another water towards themselves. Now, there's no like there's no electrons there. There's no actual Thing there. It's just a slight attraction. It's like when you're in middle school and you're slightly attracted to that one girl across the way, so you kind of get closer to her, but there's nothing really between you, right? That's a hydrogen bond. Okay? So, hydrogen bonds are forming between again the hydrogen's and the oxygen. And that actually provides water what we call surface tension and cohesion

where water just likes to kind of flow together a Lot, right? And you can see that if you like spin water together, it kind of moves as one whole thing because there's this light like attraction from one water molecule to the other and all the billions other ones in there and they kind of stay together, right? And it also flows really smoothly. And it also has we're not going to go into that because it has a high specific heat. We'll talk about that later on, but I want to focus on that dissolving. It is A

dissolver. Why does this all imply that it dissolves something? Well, dissolve just simply means to break apart. To break apart in some way, shape or form. Easy example is sodium chloride. Look at this. Sodium chloride. We know when we put sodium chloride, salt, into water, it will dissolve. Yes. Well, dissolve means to break apart. So, what's going to happen to this molecule? It's going to break apart into obviously sodium and chlorine. Why does it do that? We know that sodium is positive, chlorine's negative. So, when sodium chloride, neutral molecule, gets put into water, where do

you think the sodiums will like to hang out? And where do you think the chlorines will like to hang out? I will tell you chlorine will like to hang out right here. Sodium will like to hang out right here. Why? Chlorine is negative. It's going to hang out with the slightly positive hydrogen. Sodium is positive. It's going to hang out slightly near the oxygen, which is slightly negative. Yes, that is why water breaks apart any polar thing. It is the universal polar solvent. So basically anything most anything that is polar that's put into water will

dissolve well in the Water. So I want you to write that here. Anything polar come come into this little uh category. Anything polar in A and P that we're talking about will dissolve well in water. So therefore now sodium chloride is in this water. It's like salt water now. And the salt is mixed in with the water, dissolved in the water and it can kind of flow as one. This makes a lot of Physiological sense because your blood is made of mostly water. And your blood is carrying a variety of different really good things to

feed your cells and keep them alive. And so we use water, universal polar solvent, to help those things move through the blood successfully. Now, this is where things can get a little in the weeds, but instead of going through the details of it, I'm actually going to instead give you some Examples of things that are polar just for you to memorize, honestly. So what I would like you to remember that are polar okay so just write polar things okay polar things include electrolytes I gave you a list of electrolytes earlier like sodium chlorine potassium um

as well as we'll see later on these polyatomic ions like hydrogen positive and bicarbonate we'll talk about that later on these are buffer systems and pH but these are charged anytime you see a Charged thing it's going to be um in water. So brain, sorry I I skipped one thing. I apologize. Come back. Why do we write sodium and chlorine in our body like this rather than like this like uncharged versus charged? Because typically our body is made of mostly water. If our body's made of mostly water, it means that anything in the water has

been dissolved. Therefore, it's going to be in its charged form. So anytime you see some Sort of charged thing, so just write charged things are in water. Charged things are in water. They're dissolved in water. All right? So that's why we write them as such. Now, so electrolytes are some polar things. Also, several macroolelecules are polar. So I'm going to write proteins are polar. Proteins dissolve very well in fluid. Carbohydrates dissolve very well in Fluid and actually nucleic acids dissolve pretty well in fluid as well. These are your main macroolelecules. So remember electrolytes, proteins, carbs

and nucleic acids for polar things. All right, so we know these things if you put them in water they dissolve. Let's move on to non-polar things. Right, there's a no separation of charge within the molecule. Let me give you a list of them real quick. Gases are non-polar As well as lipids are non-polar. Those are going to be the main two that you see. So gases, things like oxygen, things like CO2, we'll talk about lipids, any like cholesterol would be a very common one, right? These are fats. These do not uh mix well in water.

They do not interact with polar things very well. So I want you to write that polar and nonpolar do not mix. do not mix. So in other words, if You were to put cholesterol or like oil, we'll write oil just as an example you've probably seen before. If you pour oil into water, does the water like mix in with the oil? No. The oil will actually sit on top and the water will sit on the bottom. they'll they'll stay separate. They do not mix very well. So essentially fats form this barrier between kind of environments.

We'll see this a little later on when we look at cells. The outermost portion of a cell Is called the cell membrane. So I'll write that cell membrane and it is primarily made of a lipid. So therefore there's a separation and on the inside of the cell most of the inside of the cell is going to be water. So like a polar fluid object and on the outside is mostly going to be water. But there's this separation of environments because the lipids don't mix in the water. So they form this little circular barrier. So the

inside of the cell, the Fluid stays there and the fluid outside stays there. And there's that defined uh barrier between them called the membrane. So that's really a common way you can apply it to A&P. All right. Now, the last thing we need to go through real real quick and then we're going to move on to macroolelecules and pH and stuff like that is how this cell membrane, which is a fat, in a way can face the water but not have any issues. Well, this is where there's a very Interesting molecule type that's kind of

polar and non-polar. that is going to be called an amphipatic amphi amphipathic molecule. So give me a second here. So let's write that up here. So this is a very important molecule in the cell membrane called an amphiathic molecule. The main one we're going to be talking about is going to be something called a phospho Lipid. Phospholipid. Okay, break that word down. Amphi meaning amphibian or lives on land and water. It means both, right? So it kind of has a both nature in a way. And so phospholipids have a phosphate group that is going to

be polar. It can face water. But then we're going to have a lipid lipid part that's going to have a long fat tail. It's going to be the lipid aspect that is going to be nonpolar. They're bound together. So essentially the polar end can face water, but the lipid and the fat end can't. And so what happens is in the cell membrane you have what's called a phospholipid billayer where you've got another phospholipid here. You got the lipid and you got the phosphate that can face the inside of the cell. So imagine this is inside

the cell like here and this is the outside of the cell here. That's where amphipathic molecules come in. So we can kind of have this intermixing of yes there's polar and non-polar but certain molecules have two ends of it and so they can kind of face both sides and be just fine. So I know I just taught a lot at you. This is a lot of details of chemistry. Very important to understand how your body works. We're going to continue to bring these concepts up as we go through these lecture series. Don't get scared. Uh

but Hopefully this gave you kind of a breakdown. And I recognize that non-polar I didn't really like show you why there's no separation of charge. I don't think that's as important. Just knowing the categories. What is non-polar? What is polar? What would dissolve in water? What would not dissolve in water is incredibly incredibly important. So I'm actually going to switch something up a little bit. I'm going to skip to Macroolelecules because it's going to apply to some of these things that we just talked about and then we're going to finish up with what is pH,

what are buffers and and why do we need to know about them. So, let's do macros. Then we're going to go to pH and buffers. All right, so on to macro molecules, which as you could probably guess that macro refers to anything that is big. So, we've got big molecules that we're talking about and there are four classes Of macroolelecules we're going to talk about. We're going to talk about carbohydrates. We're going to talk about proteins. We're going to talk about lipids. And then we're going to briefly talk about nucleic acids. So, go ahead and

write those down here with me. And then we'll roll through them pretty quick. And you can probably remember like, hey, if you're getting your macros in, you're getting those main three Um things in these three particularly in your food, but you're also getting nucleic acids from food. we just don't really talk about a whole lot. Now, that being said, I want to actually confirm a myth you may have heard. Have you heard this statement before? You are what you eat. Have you heard that before? You are what you eat. Is that true or false? It's

actually true. Did you know that? It is true. But you may say, "Well, I Ate a a hamburger and I didn't turn into a hamburger." Uh well, you kind of did. Let me explain. So, what happens is in when we're talking about the human body, we're typically talking about cells, right? Well, what do you know that the outermost membrane of a cell is mainly made of what? A lipid, right? So, lipids are the outermost membranes of not only the cell, but also the membrane bound organels. Like the mitochondria have got a bunch of lipids. The

nucleus has a lot Of lipids on the outside because it's all these kind of separations of organels. So therefore, you got a lot of lipids in cells and you also have a lot of stored carbohydrates in cells. So you might have like some glycogen in here that uh your cells store for long-term energy. Uh and then you'll also have a lot of proteins embedded in the membrane maybe holding the cell up maybe um in the membrane itself. I just said that. Uh so you might have a variety of Membrane proteins even in the nucleus. You're

going to see a lot of those. We'll talk about them later on in the cell units. Uh and then in the nucleic acids, it's all the DNA RNA that's stored in the nucleus as well as there might be some floating around in the cytoplasm. Um so as you can see a typical cell has all four macroolelecules. And fun fact, what has cells? What is made of cells? Well, any living thing. Yes. What do you eat? Living things. You eat plants and animals and their products. So therefore, you are literally eating cells. What do you do

with those cells? Well, you digest them. You break those cells apart when you put it into your digestive tract. And now you have the individual base units of all of those macroolelecules, right? So you have all the lipids and proteins, Nucleic acids that have all been chopped up by your digestive tract. And then what do you go and do? Well, you take those broken down parts and you compile them into what? Your own cells. So now you form your human cells with the same exact components that you took from the plant or animal. So are

you what you eat? Do you basically steal the little individual building blocks of these cells and build your own? Yes. That's How it works. This is literally representing eating and absorbing the nutrients. So what you'll notice is sometimes these macros are organized in these beautiful ways as a membrane as DNA in a long chain and mitochondria and glycogen all this stuff. But can they be broken apart and then put back together? Yes. I want you to remember that all of these for the most part are kind of like Lego blocks. You can break them apart

and then you Can put them together. You can break them apart. You can put them together. And fun fact, do you know what that's called? Breaking things apart and putting things together. It's just chemical reactions. Chemical reactions is basically just breaking molecules apart, putting them back together. That's all chemical reactions are. We saw that earlier with sodium chloride, right? We formed a bond, we put them together, and then we broke it Apart. Yeah. So, that's all chemical reactions are. Breaking things down, putting them together. And especially with these macroolelecules, we can do that a lot.

very similar to Lego pieces. So what we call that is when they are broken apart into their individual units. We call those individual units monomers. Mono meaning single. Mr. kind of meaning unit. So we can write single unit. And then we can also have chains of Polymers which are long chains of monomers very similar to um Legos right. So poly means many and then obviously mer unit. So as an example a carbohydrate a monomer of a carbohydrate could be like glucose or fructose or galactose. These are single units and if you put these glucose chains

together glucose kind of looks like this. We can put those together and form polymers like this. Kind of looks something like this where we have long chains of Carbohydrates. All right. So same thing with all of these. You can have individuals and then you can chain them together. Now you know that structure fits function, right? Structure fits function. So glucose can be used for very fast energy. We can actually break it down because it's got a lot of those covealent bonds. So um I know I'm going into details here, but glucose is a molecule C6

H12 06. Look at all the atoms here. Look at all the atoms here. Right? Well, all of these atoms have covealent bonds between them. How do I know that they're coalent? Well, because chonp right P always forms coalent bonds. So, these are all coalently bonded. And what's stored in those coalent bonds? A lot of energy electrons. Yeah. So, glucose is used by your body for fast energy. We break it down, produce ATP. We'll talk about that later on. But then we can also store it. We can put these things together and put It in the

form of what's called glycogen. Glycogen is stored carbohydrates in the body, stored carbs in the body and that is basically stored in your cells for a rainy day when they need some more glucose. We could if we want chop them apart, make glucose and get energy out of it. So that's a very basic way of talking about how monomers and polymers can kind of be uh used in the body. Now for uh proteins, for proteins, we know That proteins, the monomer is going to be our amino acids. Amino acids, fun fact, there are 20 different

amino acids in your body. So 20 different Lego blocks that can form different structures and shapes. And the polymers are typically either going to be just called proteins or polyeptides. Proteins or polyeptides. Now what I want you to know about proteins, these are the structure and function Of your cells. Structure and function of your cells. If your cells are doing something, it's usually because the proteins are doing it for the cells. So as an example, you've got actin and meosin. These are two proteins in your muscles, your skeletal muscles and your heart muscle actually. And

when they interact, they literally contract and pull, right? And so your body moves. So those by definition are proteins and they are Doing the structure, doing the function for your cells. Pretty fascinating stuff. And the reason they can do that is because there's 20 different Lego pieces. You could with 20 different Lego pieces virtually build an infinite amount of shapes. In a very similar way, we have 26 letters in the English alphabet and we can form just like literally trillions of different words by just organizing them in different ways. So you can form Just a

ton of different shapes of proteins. And if we have a ton of different shapes of proteins, we have a ton of different structure or functions of proteins, right? So that's why proteins are the structure and function of your body. Now lipids, lipids, they don't really have a true monomer polymer. Uh, you may hear of things called like triglycerides, triglycerides. Um, you may hear things like fatty Acids. Um, I'm not going to break those down too much in detail. Uh, but they kind of have these monomer polymer shapes, but not really. Uh, so I just want

you to remember the main functions of lipids, which are going to be basically energy storage and usage. You can use fatty acids especially as well as membrane production and insulation um as well. So you'll have some fats in Your body that help insulate and then your membranes form that barrier um between organels and cells in other environments. Um and you'll also see some lipids acting as um signaling cells. Uh so certain hormones are going to be lipids as well as uh proteins. There's also some signaling here too, but proteins just catch all. They do literally

everything like enzymes, catalyze chemical reactions. We'll talk About all these things a little later on. Last thing with nucleic acids, this is going to be your nucleotides. You've probably heard of those nucleotides as A's, T's, G's, and C's. These are basically the letters in a way of your genetic code. And when we put those together, we form DNA and or RNA. And those are going to be the main ones that we talk about. And I just want you to write information On how to build proteins. Information on how to build proteins. That's what nucleic acid's

main job is. Uh uh so let me talk on that and talk about a different type. Um so when we're looking at a cell, right, a cell has a nucleus with the DNA and mRNA that it reads off of it. that is going to inform the cell as to how to build proteins which are the structure and function of your cells in general. So it's very important that these Letters are in the right order and the right uh letters so that we know how to build the right state shaped protein to do the right function.

So that's the main role of nucleic acids. There's also a weird nucleic acid called ATP that's actually nucleic acid interestingly enough. um and that is going to be our energy currency molecule that we will talk about in chapter three um energy and metabolism. So basically any energy that is in a Glucose molecule any energy that is in a lipid molecule like a fatty acid has to has to has to be converted changed into this molecule form so that we can actually use it for the cell. So it's the usable form of energy for cells. All

right. Now, last thing with macros, I'm skipping a lot. If you want more, I'm going to attach a macroolelecules comprehensive overview video to this if you want more details on it, but how do we know that things are carbs or Proteins or lipids or nucleic acids? Well, luckily, words matter. And there are common suffixes and prefixes sometimes that you'll see that indicate what something is. So, as a carbohydrate goes, typically these will start with glide or glue. Have you seen that? Glucose, glycogen. You also may see it end in o those are the main ones

that you will likely see. So glue and o is typically What you'll see. Proteins always end okay not always a lot of the times end in iin. I mentioned actin earlier. I mentioned meosin earlier. Those both ended in n. You know they are proteins. Um, but you'll also know of enzymes, which are going to be these catalyzation of these chemical reaction molecules. And enzymes will typically end in ace, and we'll talk about those later on. So, in ace, and you also may see, I'm sorry I'm writing this everywhere, uh, pept or Pepto. Um, and those

are the common ones. All right? So, pept in ace, um, you'll see a lot. All right, moving on to lipids. Lipids a lot of the times will end in or own. Uh you'll also see oid a lot. Um so as an example, testosterone, cholesterol, glucosenoids. Um these all have lipid aspects to them. Um and I think I'm just going to stick with that those for now. Some literally sometimes you'll just see fatty acid at The very end. So fatty acid. Anytime I mentions fat, it's a lipid. And then nucleic acids literally just end in something

something nucleic acid. So deoxxyribboucleic acid ribboucleic acid. That's what DNA and RNA are. They just end in nucleic acid. All right. So that's an overview of the macroolelecules. Do you see why they are important? They're level and organization that's right basically below the organels and cellular level Because the macros literally build the majority of the cell. Very important to understand how they operate. All right. So now the last thing we need to talk about is pH. All right. So to wrap up this lecture, we're going to briefly talk about pH, what it is, what its

implications are in the human body, as well as a little bit about buffer systems. Uh so you can kind of understand how several structures of the body work, and why that's so important. So first off, PH. Well, PH, it's a P and an H. It literally stands for power or parts of hydrogen. Power or parts of hydrogen. Now, what do the heck does that mean? We know hydrogen is an atom, but more specifically, we're going to be talking about the ionized form of hydrogen, which is H+. Okay? So, remember that's just a dissolved hydrogen atom.

Now, what pH stands for is how much hydrogen is in any solution of water. So, basically, in A certain thing of water, how much hydrogen is in it? All right. So, how does that look? How does that look in this case? Well, we have a scale that we're going to use called the pH scale. And it's going to run from zero at the beginning all the way up to 14 at the top. Now, what's kind of interesting is as you get further to the left towards zero, the more hydrogen ions there are. And the further

you get to the right, the fewer hydrogens there are. So Basically, you could think about this as the closer to zero, the more hydrogen. The closer to 14, the less hydrogen. That's kind of weird because you'd think pH parts of hydrogen. You think more hydrogen would be a higher number, but it's actually the reverse. So make sure you get that in your mind. Okay. So now, what would this look like? Well, if I had say a solution of water that's on this side, okay, the further left side, we'd have this water and we just have

a Ton of hydrogen ions packed into the water that were added from some molecule. Maybe hydrochloric acid, maybe other things. But then if you're on this side, you will just have fewer. So maybe just one. All right, so that's just what it would look like. And that's the difference. Now, several things to break down here. You mentioned me say the word acid earlier. If we are closer to zero, we are going to be more acidic. Acidic. If you are closer to 14, you Will be either one of two names. You'll hear either alkaline or you

can also hear the word basic. You'll hear both interchangeably. Now, you'll notice it changes right at that middle part, which is going to be seven. And that is going to be considered a neutral pH at seven. And interestingly enough, the one neutral molecule is actually going to be water. So if you have pure water, you should have a pH of seven, right smack dab in the middle. Okay. So that being said, what are some implications here? Well, we know that in the body your blood pH is about right here. So I want you to remember

this blood pH, sorry that I'm drawing a blue, blood pH is around 7.35 to 7.45. That is your homeostatic range for blood acidity, blood pH. All right. Now, true north obviously is going to be 7.4. That's perfect. Uh but it's anywhere in that range is healthy. So, our blood is slightly what? Slightly alkaline. Yeah. But then you can also look at a structure specifically inside the um stomach's lumen. So, inside the stomach and that's going to be hydrochloric acid H. And that's stomach acid. And as you can see, that is very, very, very acidic. It's

usually around zero to one pH. All right? So, we have different acidities of uh things in your body. Um, but the main one we're going to think about is blood pH because that is actually going to be a homeostatic set Point. I want you to write that homeostatic set point. Why do we need to keep blood pH in homeostasis? Why do we need to keep your blood around there? Well, we know your blood your blood is full of different proteins. Blood is full of proteins. Okay? Things like uh some examples of proteins in your blood

would be like hormones. Uh things like carrier proteins we'll talk About later on. Um and then also enzymes. We'll see enzymes, little things that do chemical reactions for you. We'll talk about in the next video. These are all proteins. And what's really interesting is proteins can denature if they are out of the correct pH. They can denature if out of the correct pH. So in other words, these proteins in your blood like the pH to be in here. Yeah. But if they get out, so say now Your blood pH is 7.2 two, for some reason

it's out of homeostasis. Your proteins could denature. They could lose their nature. They could lose their nature. What's their nature? How they're built, their structure. And if the proteins lose their structure, obviously they will also lose their function. Okay? So, we need to keep our blood pH in that range to keep our proteins functioning, the structure and function of our body so that they stay in the Right structure so they don't denature and lose their function. Does that make sense? All right. Now, the other thing I do want to mention real quick here is that

proteins can also denature if out of the correct temperature as well. So that's why body temperature is also a homeostatic set point because these proteins stay in the right structure um when they're at adequate temperature in adequate pH. Very interesting, huh? All right. So that's why these are Homeostatic set points. Now how do we keep our blood in that range? How do we do that? Well, a lot of the times the body will use what's called buffer systems. Buffer systems. Now what buffers are, these are anything that help resist the change in pH. Resist changes

in pH. So this is basically saying, hey, we want it to be here. What would happen if the body uh got some acid inside of it? So interestingly enough, I want you to Write here, and we're going to talk about it later on. uh if you add CO2 to a solution, we actually add hydrogen ions to it. And if you lose CO2 out of a solution, you actually uh lose hydrogen's ions out of it. So that's kind of interesting. But the problem is what's happening in your body is you have a bunch of cells that

are like little smoke stacks and cells are constantly producing CO2 and throwing that CO2 into the Bloodstream, high to low, right? CO2 is a gas. diffuses right across all these membranes, gets into the bloodstream, and now we have a lower pH, right? Because we're going to add CO2, we're going to become more acidic. So now our blood pH could get off. What could we use to help resist that change? We could use buffer systems. Okay, so buffers help resist changes in pH. I like to think of buffers as basically um A way of uh lifting

weights. So, let's draw an example real quick where we have um let me draw this. We've got a barbell right here. Okay. And that barbell sitting horizontally is going to represent that pH of 7.4. That's our blood pH, right? And on each side, we're going to add some weights in this case. So, we can either add weight that's red or we can add weight that is blue. Okay? This is going to represent any alkaline substance. This is going to represent Any acidic substance. Now, if I was just teetering this weight on a very thin bench,

okay? And I decided to add just the smallest bit of acid, maybe some CO2. I add some CO2 or I add some uh acidic substance. What would likely happen to the horizontal bar? Well, would likely tip down rather rapidly and there would be a drop in pH, right? there'd be a drop in pH and now your blood pH maybe goes to 7.1 and You're out of homeostasis and that is bad, right? You could denature your proteins. You could potentially die. So, what buffers do instead and and by the way, like you could do it either

way, right? Like what if you took weights away here? What if you uh took some of the weights here away? Took some of the acid away. Uhoh. Well, now that part is going to drop and you'll actually have a pH rise maybe to 7.6. Also bad, right? So either way, if you had too much of Either one thing, it's a bad thing. So how can we fix this uh process? How can we fix this process? Well, let's try. What if I added a weight rack that would help hold the weights like this? So now I've

got my weight rack, my barbell is through here, and I have my weights. What would happen if I added some weight on one side? So I add another hydrogen ion or something That bar would stay the same appro approximately, right? Because you have that leverage to hold onto both sides of the bar. So the pH stays at around 7.4. So buffers exist to basically even if there's a lot of something or a less of something else, it'll hold it steady and keep that pH adequate at 7.4. Now, obviously, if you were to add a ton,

like add a ton of acidic substances, eventually it would fall, but the buffer is going to be this little support System. This is the buffer. All right. Now, the most common buffer system you'll talk about in A&P, we'll see later on, is something called the biccarbonate buffer system. I'm just going to introduce it. We'll talk about it probably inparent buffer system where basically let's say we've got some hydrogen ions over here and then that's making it acidic, right? Well, if we add bicarbonate, Which is H3 minus, so we add some of this to a solution,

what will happen is is we're going to push the reaction this way, form a new um molecule called carbonic acid. And that carbonic acid is just going to kind of hold onto it, just keep it there. And as you notice, if we did this, we added bicarbonate, we took the hydrogen ion away, and now we have a new molecule. Do you see any hydrogen ions by themselves now? No. So therefore, it's Not too acidic anymore. So we've buffered it and we're not going to change the pH too much. If you want more details about how

that buffer system works, I'm going to actually link two videos here. One is more about this kind of weightlifting analogy and then one is going to be about how uh buffer systems work in both directions because if we have too many blue, we have it too high. And if we have too many red, we have it too low. So, how do we kind of Interconvert them based on our certain circumstance? But if you want to watch the next lecture once it is produced about enzymes and energy and metabolism, it's going to be right here. Thanks

for watching.