hello bisque 132 this is the beginning of recorded lecture five one um starting off on the circulatory system so we've actually talked about circulatory systems before in previous chapters we compared and contrasted open circulatory systems and closed circulatory systems in various groups of invertebrates and vertebrates so there's a bit of this in the chapter that i'm skipping because we've done this already for the rest of this chapter what we're going to be talking about is closed circulatory systems uh so we've said all we need to say about open um in previous chapters so let's start by talking about blood so there are three main components to blood uh platelets small things here blood cells coming in all sorts of different uh types and sizes and you can't see it here but it's everything else that they're suspended in plasma so blood if we're talking about whole blood uh that refers to plasma plus blood cells plus platelets all three of these things together make up blood so let's start by talking about plasma uh plasma is defined in the key terms as the liquid component of blood that is left after the cells are removed so this is the liquid component so unsurprisingly it's mostly water but there are other things in plasma as well you should think of this as as really as small stuff uh so plasma also contains nutrients you know stuff like glucose that your body is circulating around to get from one place to another uh wastes stuff like urea that we'll talk about in a later chapter that circulates in the in the bloodstream and it's part of the plasma hormones you know signaling molecules that your body is using to to send messages from place to place um ions stuff like the carbonate bicarbonate buffer that is um used to buffer ph in the blood again maybe you're seeing a pattern here these are all you know fairly small molecules uh we're getting a little bit bigger here proteins including fat carriers uh and any other proteins in fact some hormones are proteins but again these are definitely much smaller than a cell part of the plasma proteins are part of the plasma and then clotting factors this is another protein we'll talk about a little bit when we talk about clotting and this brings us to another term that you'll see brought up when talking about blood and blood products and that's the term serum serum is basically plasma that doesn't clot so the key terms define serum as plasma without the coagulation factor so when these things have been removed or destroyed somehow uh we we call this serum instead of plasma so okay that's straightforward enough let's talk about the cells next so there are actually two different types of cells red blood cells or erythrocytes and white blood cells and you can see many different types here and this is definitely not even naming all of them but all these other ones called leukocytes so red blood cells all you know abbreviated as rbc uh also known as erythrocytes um erythrocytes uh have kind of a weird shape i i always think of this this horrible butterscotch candy the werther's original as sort of a shape of an urethra site the other very strange thing about them is they don't have a nucleus so don't memorize this but but this is showing that during their development of of course early on they have a nucleus but as they differentiate at a certain stage they actually eject their nucleus and uh you know continue on as as as a cell without a brain essentially a cell without a nucleus and we had discussed this uh in the last chapter that their job is to carry hemoglobin which carries oxygen so i guess you don't need a nucleus to do that if you're just a bag filled with protein that's carrying oxygen so these erythrocytes disc shaped with no nucleus and they contain hemoglobin which carries out too that's a good enough summary there so what about all these white blood cells well i'm to kick the can down the road and not really talk about these at all i'm going to save it for the immune system chapter so white blood cells abbreviated wbc also known as leukocytes involved in the immune system we will get into more of of their function of the different types when we get to that chapter so that's it for now all right so we've done plasma we've done cells the only thing left is platelets so as you can see here platelets are much smaller than a cell they are not cells they are cell fragments uh and you could see this even more clearly when you look at how platelets are made so here's the megakaryocyte that is making these and yeah it rips off pieces of its membrane a little bit at a time and that's how platelets are created so cell fragments their job along with some of the proteins that are present in plasma their job is involved in clotting so if you have a a wound or something like that that you know breaks uh the wall of a of a capillary your your plasma your blood is going to start leaking out in the to the surrounding tissue and that is uh that's no good um so if you have a hole in anything the first thing you want to do is patch that hole so you can prevent leaking and so um platelets along with um you know fibrin a couple of other proteins that are present in plasma but not serum are going to form a clot that's going to plot plug up this hole so platelets or cell fragments involved in clotting along with proteins okay so that that was just you know talking about blood as far as you know what it what it is and what its components are let's now talk about circulation how this blood moves around now this is kind of a complicated process but i think by breaking it down step by step it's it's not going to be as intimidating as it looks and so this is a this is a never-ending circuit uh and so there really isn't a beginning or an end but arbitrarily let's start in the the body and the head so what i'm calling step one but again this is all arbitrary blood in the body and the head loses its o2 which should make sense that that's the the job of blood or one of the many jobs of blood is is to give the o2 that it has been storing to these tissues that need it so the o2 is given to surrounding tissues the blood is now what is called deoxygenated it's it's given away its o2 and this deoxygenated blood is drawn the color blue so and in this figure but i mean every every circulation physiology blood flow you know figure that i've seen in any textbook ever seems to follow this convention that you know here we have the the blood in the body or the blood in the head you know getting rid of its o2 giving it to the surrounding tissues and and now it's blue i i making a fine point of this your blood is always red you're uh if you have pale skin sometimes your blood can look blue in in certain places but that has to do with how light is filtered through the layers of your skin your blood is never actually blue it's always red but it is a convention that is you know convenient for these figures that deoxygenated blood is drawn the color blue so okay now we could we can guess what needs to come next i mean this deoxygenated blood needs to get oxygen so we can do this whole process again but they're going to be a few steps before we can do this so step number two uh blood enters the heart through veins so okay they're gonna be a few terms as we go through this process of blood circulation a vein is defined in the key terms as a blood vessel that brings blood back to the heart so if it's if it's traveling toward the heart it's traveling in a vein just just know that so blood enters the heart through veins into the right atrium so this is the first of four chambers that we're going to bring up uh the right atrium here and again these these are also color-coded they're blue because they're dealing with deoxygenated blood now you might be looking at this as i you know confidently move my mouse around the right atrium and think this is on the left what's going on here well another convention in every textbook ever is when when you're looking at a heart you are looking at the heart of a person imagine this being a person you know like this standing in front of you you know facing you so this is this is their right side even though it's on your left and this is their left side uh even though it looks to be on your right so anyway sorry if that's confusion confusing but that is just the way it's done you are looking forward at the heart of a person who's looking forward at you so okay this deoxygenated blood is coming in through veins into this atrium so we're actually going to see a couple of atria again there are four chambers in the heart uh keep this in mind blood enters heart through atria uh so anytime blood is coming into the heart the chamber is an atrium chamber atria is just plural okay so again we know what's what's supposed to happen this deoxygenated blood is supposed to go to the lungs so it can get oxygen but before it can do that um we need some power to send it to the lungs so this this low low pressure chamber this atrium where the blood just entered after making its long journey throughout the body um it's got to move to a different chamber so it can be pumped to lungs so this deoxygenated blood moves from the right atrium to the right ventricle so blood is pumped from the right atrium to the right ventricle and importantly there is a valve here that makes sure that this movement is uh is one way we don't want backflow we definitely don't want this system going in reverse uh so if there there is a valve here that ensures one-way movement uh but by the way yeah there there are names for this valve and the other valve there are names for these veins and arteries and stuff i'm skipping over a lot of details that i don't think are important in an intro course so yeah just remember that what i have on these slides is what i want you to be familiar with for an exam so okay we are now in the right ventricle and finally we're able to go to the lungs so blood reminding you this is still deoxygenated is pumped through an artery to the lung so an artery is the opposite of a vein it's defined in the key terms a blood vessel that takes blood away from the heart so veins go to the heart arteries go away uh deoxygenated blood pumped uh through an artery to the lungs uh and blood exits the heart through ventricles so again we are in the the right ventricle now going toward the lungs uh you can this will this will bring you a long way towards uh towards you know being able to answer any test question if you remember these two statements blood always enters in an atrium through atria and uh blood always exits through a ventricle so here on in the right ventricle we can we know where it's going it's exiting the heart because it's a ventricle so um at this point uh we're at the lungs uh and in the lungs the blood is going to pick up o2 from the from the surrounding air so now we're going to go from deoxygenated to oxygenated so there we go at the lungs uh blood obtains o2 it is now oxygenated and again it's now drawn the color red it's always red but oxygenated blood is now drawn the color red so okay we logically we know what's about to happen or what's going to eventually happen this blood that has o2 is supposed to deliver it to the body but just like we saw before in order to make that trip you got to go back to the heart again so this oxygenated blood is going to come into the heart now on the left side remember blood always enters in an atrium so here comes in from the lungs into this left atrium so oxygenated blood enters the heart from the lungs at the left atrium and again we know that if uh we're gonna exit it's gonna have to be through a ventricle so before this blood can make its exit to the the head and the body it's going to move from the left atrium to the left ventricle and once again there's a valve here that makes sure that this movement is one way so blood is pumped from the left atrium to the left ventricle valve ensures one-way movement here and uh again we know what's going to happen that this is the a ventricle so it's about to leave the heart it's oxygenated blood so we know it's not going to the lungs it's supposed to go to the the head and the body and that's exactly what happens here blood oxygenated is pumped from the left ventricle to the head and the body and and from there it's going to deliver its o2 and that's right where we started again blood in the body and head losing its o2 and then you know the whole process repeats itself um another thing that uh if you keep in mind we'll help you remember what each of the four chambers does again i said blood enters through atria and exits through ventricles also keep this in mind the right side always deals with deoxygenated blood and the left side of the heart always deals with oxygenated blood so again the right side whether it's the atrium receiving deoxygenated blood or sending out deoxygenated blood the right side is always blue drawn blue it's always dealing with deoxygenated and the the left side again whether it's receiving or sending out it's always dealing with oxygenated blood so so keeping this in mind will will help you a lot as well now there are actually three different circuits that exist in blood circulation so that this is just some some terminology here the pulmonary circuit is what we call the part of this journey that we talked about from the heart to and from the lungs so yeah this is the the pulmonary circuit here from the heart to the lungs to get oxygen then back to the heart again uh the systemic circuit is the other one we saw from the heart to and from the body so there's the systemic circuit going to the body and the head losing its o2 and then back to the heart again but i just said there were three circuits and then this is this is only showing two so what could the third possibly be uh the third is called the coronary circuit which is easy to forget about but the heart needs blood the heart is a muscle the heart is working very hard and the heart muscle itself needs to be supplied with oxygenated blood the blood in this chamber well first of all only half the heart gets to have oxygenated blood but it's not really getting a chance to absorb this o2 that's you know as it's flowing through these chambers so we need to have veins and arteries um connected to the heart itself this is called the coronary circuit from the heart to and from the heart kind of a weird way to say that but yeah the heart muscles must have veins and arteries themselves and i referenced this earlier there are names for all of these things but we're definitely not not going to worry about this level of detail in an intro course so there's one uh last topic in this chapter that i think is worth uh worth uh discussing before we move to the next chapter uh and that is comparing and contrasting uh vertebrate circulatory systems so uh this uh the circulatory system that we've been looking at so far is uh what we see in mammals and and birds uh this four chambered heart you know everything we just went through that's how mammals do it that's how birds do this it's called double circulation because it is you know basically a figure eight the systemic circuit the pulmonary circuit um those are the two main big circuits so it's called double circulation this is defined in the key terms uh flow of blood in two circuits the pulmonary circuit through the lungs and the systemic circuit through the organs and the body so four chambered heart double circulation everything we just talked about mammals and birds so how is this different well in reptiles let's move to a from mammal bird circulation to reptile or most reptiles see if you can spot the difference so a lot of this looks uh looks very similar you have a systemic circuit here you have a pulmonary circuit here to the lungs if you're if you've got a sharp eye you might notice the difference is here in the heart so in the mammalian and bird heart the chambers that hold oxygenated blood and the chambers that hold deoxygenated blood are completely separate from one another it looks like they're you're they're mixing here it's actually just crossing over they're completely separated from one another you don't want blood with oxygen in it and blood that doesn't have oxygen in it to mix with one another uh because then you'd you'd end up sending red blood cells with no oxygen to the body and head and that's a waste or you would send red blood cells that have oxygen to the lungs which would be a waste so they're completely separated here but in most reptiles they're not there's a septum that incompletely divides this chamber and you have a little bit of mixing it's sort of drawn purple here uh in between oxygenated and deoxygenated blood this is obviously not great uh but it is the way it is in most reptiles so most reptiles have a three chambered heart there is a partial septum this is like the fifth time we've seen the word septum in this course the septum is just a wall or a barrier or whatever so there is some mixing of oxygenated and deoxygenated blood this is very bad but you know it is what it is uh and this is still a double circuit this is still double circulation but you have you you have this mixing now let's move from reptile heart we're kind of going backwards evolutionarily so uh things are getting getting more primitive and more simple as we go back let's move from reptile to amphibian spot the difference this mixing is even worse without even a partial septum to divide this chamber this is a a fully you know three chambered heart where there's a lot of mixing of oxygenated and deoxygenated blood and that's really not great as far as efficiency goes so amphibians have a three a three chambered heart no septum at all mixing of oxygenated and deoxygenated blood that's bad like i said in the last slide and this is still double circulation though okay moving backwards again from amphibians down to fish uh whoa this is completely different so uh there's no mixing of oxygenated and deoxygenated blood because fish circulation has just two chambers to the heart one atrium and one ventricle and so uh instead of making a figure eight of one loop to and from the lungs or the gills in this case and another loop to and from the body in a single loop this blood is pumped from the ventricle to the gills to acquire oxygen to the body to the liver oxygen and then back to the heart again so fish have a two chambered heart with a single circuit circulation so let's review this again so this is the simplest way to have a heart and these are the the simplest vertebrates with two chambers it is kind of an upgrade to to do this in two loops uh it allows you to you know pump more effectively if you're making two different circuits here so this is kind of an upgrade even even though there is some mixing and obviously you know we see a further upgrade in the partial septum of reptiles and then we see sort of the peak performance of the heart uh in the complete separation what we see in mammals and birds so again i thought this was this was interesting uh to explore the differences in circulation among these vertebrates all right that does it for circulatory system now on to the immune system okay this is going to be a big chapter and so we can actually divide the immune system into two basic halves or two parts um the innate immune system and the adaptive immune system let's start with the simpler one and and we'll get we'll get more complicated as we go through so the simpler of the two is called the innate immune system so the innate immune system i'm double underlining this because there are going to be several things that are a part of this and i'll underline those so just my way of organizing the innate immune system has limited pathogen specificity so pathogen is a term i'm going to use a lot in this chapter because a pathogen is a bad thing something trying to cause disease the key terms define this as an agent that's very vague usually a microorganism that causes disease in organisms that it invades so i'm being vague like this because this could be a bacterium this could be a eukaryotic parasite this could be a virus so all of those things some of those are alive some of those are not alive virus is not alive um all those things fall under the heading of pathogen if it's it's trying to harm you it's a pathogen so again using this word a lot in the chapter so the innate immune system is not very limited or specific about the pathogens that it deals with it fights against pathogens certainly but not in a very specific way the innate immune system is however very immediate uh the the other immune system is is going to take a little bit longer but this is much faster but not as specific so the first part of this i want to talk about is actually the largest organ of the human body it's a fun trivia question here and he guesses the largest organ is the skin uh so google image search supply supplying some skin here if you didn't know what this looked like uh looking more closely at a patch of skin here oh hey i was talking about receptors last time i used this uh this slide but there's a lot going on here the part that has to do with the immune system though is the the outer layer this thick layer of epithelial tissue as well as the sweat created by sweat glands and excreted here it provides a barrier to entry so the skin is just a physical barrier that prevents stuff from getting in um if we want to zoom in even further here oh don't sweat all the detail here but there's a lot of stuff going on other than just epithelial cells so you have oils here and you have sweat which is at a low ph this creates an environment that's actually not a great place to live even though this is a lot of available real estate it's pretty inhospitable because of the oil and the sweat and the locals so i referenced these way earlier in the quarter in our chapter on prokaryotes but we have a lot of normal flora normal bacteria and fungi that make their home in this environment and so the normal flora with the sweat and the the oils make this just a place that's not a great place to live so the skin is an inhospitable environment for pathogens it's a good way to put it low ph and the normal flora crowd out pathogens just uh make it difficult for them to get a foothold here now as great as the skin is this cannot cover our entire body we need entrances and we need exits so to cover those parts of the body we have what are called mucosal epithelial surfaces so these are epithelial cells that secrete mucus this is the nasal epithelium we're looking at here but most mucosal epithelia are the same way you got these cells and then you have a layer of mucus that they have secreted as like an additional layer of protection for these cells so mucosal epithelial surfaces are at entrances and exits of the body cells secrete mucus and enzymes the mucus just you know traps and destroys things the enzymes a lot of times are specific uh um well not too specific but uh will actually destroy pathogens the the one that comes to mind your eyes so that's another entrance to the body technically make an enzyme called lysozyme that targets peptidoglycan remember that compound it's part of the bacterial cell wall so uh they're gonna trap and destroy pathogens and again this is part of the innate immune system this is all very generic mucus is gonna trap just anything that gets stuck in it and you know those enzymes have to have a bit of specificity but bacterial cell wall that's definitely not a specific species of bacteria so this is the to whom it may concern part of uh of the immune system so what about the cells uh what about leukocytes so there are some leukocytes that are involved in the innate immune system in addition to you know these epithelial cells one way in which leukocytes involved themselves in innate immunity has to do with pattern recognition receptors and pathogen-associated molecular patterns okay so the immune system as a whole becomes a lot of alphabet soup after a while so i'm gonna try to go through this as as simply as i can so um here's the leukocyte it's a macrophage it has a pattern recognition receptor or prr let's break this down pattern recognition receptor so it's a receptor it recognizes something it binds to something pattern recognition means it binds to some specific pattern so uh the pattern recognition receptors are on the leukocytes the patterns that they are capable of binding are on the pathogens so here's a bacterium for example the the pamp is a pathogen-associated molecular pattern so again it's a pattern associated on a molecular level with a pathogen a pamp is basically a bad thing a thing that you you associate with a pathogen it's it's never a good thing um more alphabet two lipopolysaccharide lps is is one of these those pamps it's it's bad stuff it's found on gram-negative bacteria we do not have this in our bodies so if you encounter lipopolysaccharide that's always going to be associated with a pathogen with something bad so the let me write down what i have so far so pattern recognition receptors or prrs present on some leukocytes for example macrophages we're not gonna we're not gonna name the learn the names of all the leukocytes but this this is an important one the macrophage so the the prr on something like a macrophage binds to a pathogen associated molecular pattern or pamp on again common pathogens so there's some specificity here but this is all still kind of generic for for common pathogens so what happens when this recognition happens well again that tells this macrophage hey something bad is happening here and so it's going to send out a bunch of signaling molecules called cytokines more alphabet soup interleukin-8 interleukin-1 tumor necrosis factor alpha my point is these these are cytokines um so this binding leads to the release of cytokines and eventual phagocytosis of the pathogen so cytokines are defined in the key terms these are signaling molecules used by the immune system i'm sorry i'm reading the wrong thing chemical messenger that regulates cell differentiation proliferation gene expression and cell trafficking to effect immune responses it's kind of wordy but it's a message it's a signaling molecule that tells the immune system to do something so anyway prr binds to pamp cytokines are released phagocytosis so this is how your immune system deals with viruses and bacteria these cells will eat the pathogens they engulf the pathogen and uh and destroy it uh from the inside sending it to the lysosome if you remember that organelle back from bisque 130. so that is how uh that is how the these leukocytes deal with a specific pathogen and again there's some specificity here because it's only something that happens to have this common danger pattern on it but it's also very generic any gram-negative bacterium any species or whatever anything that has lps for example is going to be destroyed through this process so that's why this is the innate immune system it's it's pretty generic for what you're going to fight against so another way in which leukocytes can be involved here is at the site of injury so phagocytic leukocytes which they're leukocytes that do phagocytosis that includes uh neutrophils uh and the macrophages so macrophages you know are kind of smart they recognize stuff but they can also you know eat things they can also fight uh so phagocytic leukocytes like neutrophils and macrophages can be brought to the site of injury by cytokines so here's a wound site again you've been stabbed with something uh obviously there's you know some blood leaking out here and all the stuff we talked in the last chapter about clotting but also you get some pathogens that you know make it past you know this primary barrier this primary line of defense uh we got we got to bring in some some cells to try to deal with this so the damaged cells will actually send out cytokines that recruit the that bring these leukocytes to the site of of injury and they're going to do phagocytosis on the bacteria or the viruses that have managed to get past the skin so this uh this is called inflammation when this happens when you have the sight of an injury also in the key terms localized redness swelling heat and pain that results from the movement of leukocytes and fluid through opened capillaries to a site of infection so a lot of the symptoms of just like ah man it's so swollen and it's hard to move if you you have an injury somewhere a lot of that is due to your immune system you're bringing stuff into that site to try to deal with these pathogens and just bringing a bunch of stuff in is gonna lead to swelling and heat and redness there okay so that is not definitely not the end of the immune system but uh and not even the end to the innate immune system but this is a good cut off point this is typically where i've run out of time in lecture five one this is the end of lecture five one uh more immune system stuff in the next lecture