and crucial life functions so that's what that says if you don't have this printed I can't fit all of this in this particular screen there we go so there are about six crucial life functions these are pretty broad but we're going to start to narrow down how this organism called a human actually functions and what is required for us to stay alive so the first one we're going to look at these are crucial life functions again there are six of them and here is the first one maintenance of boundaries that is absolute requirement for any organism even uh a unicellular life form floating in the ocean would require maintenance of boundaries such that you know its internal environment cannot be allowed to equilibrate with its external environment that's likely going to lead to some sort of quick death so humans are definitely um you know sort of in that category where we have to maintain some pretty substantial boundaries so I'm going to talk about external environment and how that's different than internal environment I've left some space here because I'm going to obviously draw this out it's not as simple as one might think it's not just whatever is on the outside of the skin is outside and whatever's inside of the skin is inside it is not that simple so we're going to start with taking a look at what is this thing called external versus internal environment and then by the time I get done sort of explaining that I'm going to come down here and talk about how until something whether it's oxygen glucose ions a pathogen disase causing organism until that crosses an epithelial tissue barrier that thing is technically external uh and so that's kind of an interesting thing to think about it kind of changes how you perceive the arrangement and organization and honestly structure of the human body remember the four tissue types we talked about on Tuesday primary tissue types is this one of them epithelial tissue is that a primary tissue type yes indeed it is the other three are con connective tissue muscle tissue and nervous tissue so wherever we find these primary tissue types in the body they tend to have the same job so this is our first example of that epithelial tissue wherever we find it serves barrier function and it does a really good job at that um so we think about some common areas of epical barriers that serve as these um prevention of internal and external environments equilibrating we're going to see them pretty obvious areas like the epidermis the outside of the skin but we will see them in likely less common areas that you were thinking the lining of the gut tube the GI tract that's epithelial tissue the lining of the respiratory tra that's epithelial tissue and so that's why you can bring in a big chunk of the external environment by eating or breathing and until it crosses one of these barriers it stays in the external environment that turns out to be pretty helpful because think of all the germs you eat whether you cook your food well or not you still have germs on them uh things you breathe in I think Kansas is a great example of holy cow I didn't know that could even be in the air and then it Rams in your lungs at like 80 M hour thanks to the wind so all sorts of things that come into our body that hopefully never cross that barrier so they don't make us sick so there's a lot of benefit to that so epithelial tissue wherever we find it serves this purpose so let's talk about external environment versus internal environment so external environment see if I can find a good pen to work with here external environment is anything I'm going to start with a super obvious statement outside of a tissue called epithelium and epithelium is just another way of writing epithelial tissue epithelium and epithelial tissue are the same thing and I'm going to give you sort of a general outline of how this works wherever we find epithelial tissue forming this boundary It generally has the same pattern and I'm going to be using the example of the getu the GI tracks for this it would be very similar if it was the skin or the respiratory tract or the urinary tract but what we're going to see external environment versus internal environment is I'm going to take something that is too like so I'm going to draw it sort of three-dimensionally here so you can kind of get an idea of what I'm talking about I'm going to take this tube I'm going to call this the gut tube GI tract any tube function any organ that is a tube and if I was to cut it right there on the transverse plane and turn and look at it I would actually see it really easy to identify outside versus inside so tube organs like the gut tube the respiratory tract if I was to cut this I would see this transverse section that has a strange kind of wrinkled appearance and on the outside of that I would find a bunch of other structures that are going to help contribute to this boundary this border that I'm forming here but it's really the epithelial tissue that does the majority of this work inside of this I'm going to find the actual internal environment of the body so outside of the epithelium this is going to be so outside I know this is going to be a circle but outside of this epithelium we actually find external environment and some of you are like but that's inside the circle and I would say I know that but epithelial tissue is the boundary the border so the Lumen of this tube is external environment see if I can write that bigger or if I just make it Messier the Lumen of the gut tube the actual interior of this tube where I've just written external environment the Lumen that's external environment so that means from the oral cavity all the way to the large intestine that stuff that you eat stays in the Lumen of that G and until it crosses that pink line right here showing you AC cross cross section of this until it crosses this line right here it's technically always part of the external environment to contrast that with the internal environment I'm going to draw what's just on the other side of this epithelial border and that would be blood vessels there little tiny capillaries all surrounding the gut tube the respiratory tract reproductive tract urinary tract so this Blood sitting in a capillary that's definitely internal environment so it turns out the Line in the Sand is this epithelial border right here until it crosses that technically external environment another way we could look at this see if I can get this to focus a little bit better is the skin maybe we could take a look at a epithelial tissue that's not tubular in function so for that I'm going to come over here where I have a little bit more space draw the same thing but a different orientation and sometimes that helps you kind of understand the concept A little better the outside of your skin is called epidermis and it's pretty wavy looking under a microscope anyway and there is this Line in the Sand where the epidermis ends and the dermis begins and that line in the sand is our boundary between an epithelial tissue and the tissue below which is the dermis so here the outer part of the skin is called epidermis that's an epithelial tissue below it we have the dermis and that's a connective tissue so we kind of talked about this before but I'm sort of changing the concept or the focus a little bit more anything outside of this epidermis or epithelial tissue is technically outside of the body so we could have as I mentioned before some pretty nasty pathogens on the skin then that's my attempt at drawing a bad bug but until it gets into the connective tissue below where you have all these little blood vessels all these little capillaries it's technically going to stay in the external part of the body so external versus internal so even the skin and the GI tract are very different organs they're both an epithelial tissue and they have the same function all that differs is the structure so it's interesting we can devise these primary tis tissue types epithelial tissue all we have to do is put them in slightly different places alter their structure a little bit and we have similar function but in very very different locations so that's epithelial tissue maintenance of boundaries that is a big key player for keeping us healthy also for keeping us hydrated because right inside that blood is an awful lot of water and if we lose our epithelial barrier then we can become dehydrated pretty darn quickly and there are pathogens that will do that for us as well cha is one dehydrates it kills by dehydration let's talk about our second crucial function for Life moving away from maintenance of boundaries we're going to come down here and talk about our next one which is metabolism metabolism is a complex set of reactions so when we think about an energetically expensive reaction or if I say something is energetically expensive I'm talking about energy in the form of ATP cellular energy just to be clear so when we think about how much energy is required to sustain a large organism like ourselves it is a lot you know between 2, 2500 kilo calories per day and that's just for the average person that's not Super Active that's a lot of calories so we measure our food in Kil calories or C cows so that is going to we hope provide a lot of ATP let's talk about what we're going to need though to produce this ATP we're going to need nutrients enzymes and often overlooks but I hope you don't waste removal we're going to use blood to provide the inputs to make ATP that blood will carry nutrients cells then which have enzymes can use those enzymes to alter those nutrients make the ATP but you also have waste removal and I'm going to talk about the value of all of this for ATP production so let's come over here and talk about just a single cell just a single cell what it's going to make as far as waste what it's going to need as far as puts so I'm just going to draw this cell over here give it a nucleus just so we know it's a cell and of course cells have to have a blood supply we talked about that on Tuesday do you remember how close most cells have to be to a blood supply in order to survive I gave a number anybody remember that it's about 10 micrometers it's very very close the the reason being is that diffusion is a slow process diffusion is a very slow process so if we're going to have nutrients diffuse out of the blood and into a cell then we cannot have a huge distance that we have to span very slow process so let's talk about what we might need to get this cell the stuff that's required for ATP production oxygen talked about that on Tuesday O2 molecular oxygen and I'm just going to stick with this sort of simple stuff glucose C6 h12 06 cells like to make ATP out of glucose it's they're set up to handle it so here are some inputs can you remind me what process this cell uses to get oxygen from the blood through the extracellular fluid across the cell membrane and into its intracellular environment what is that process simple diffusion great similarly we need glucose it's going to have to take a little bit more complicated route what is that process called facilitated diffusion facilitated diffusion facilitated diffusion because we need some sort of channel in the cell's membrane to get that glucose into the cell once oxygen and glucose get into the cell of course we'll have enzymes that start the process of ATP production hexokinase for example that's a really important enzyme so from that we hope the cell is able to make adequate amounts of ATP and it's pretty happy about that but in doing so it's going to produce some byproducts and equally important to nutrient provision is the removal of byproducts because cells if they are allowed to accumulate in their own byproducts or waste they don't like it any more than you would imagine if nobody ever took out the trash at your house maybe some of you have that going on right now getting used to new roommates um but nobody likes to sit in their own waste right just to make it very blunt cells are no difference so what do we need to contend with to get these byproducts out of the cell what are these byproducts give me some byproducts of ATP production CO2 that's great I'm going take that CO2 so in the process of making ATP we're going to produce CO2 got to get rid of that what's the other ambiguous often forgotten byproduct it's a byproduct of any enzimatic reaction water's not bad the cell will probably use it and it will be dissipated through the skin there's your hint you said it not water it's heat heat is always this byproduct that's sneakily accumulating from enzymatic reactions and we always have to contend with it this will be especially true when we start talking about body temperature regulation how can heat from metabolism creep up and literally kill you so we have to manage that so CO2 and the easy to forget because you can't see it heat these have to be managed how do we get rid of CO2 well it diffuses out of the cell via simple diffusion and into the blood and the blood will carry it away to the lungs where it's expelled heat also carried by the blood heat also moves with diffusion and so you can't really see it so it's hard to understand that at first but heat moves with diffusion so this blood will get warmed as it moves through these cells that are going through cell respiration and hopefully that blood goes to the skin the surface for dissipation so there's a lot to contend with when we talk about metabolism and this is the big picture I like to sort of impart on students what metabolism looks like from a physiological perspective I will talk a little bit about the enzymatic reactions broadly that are also part of this but physiologically Ally This is how people get in trouble when they have lung conditions COPD bronchitis asthma when a person has those lung conditions pretty common by the way oxygen attainment by cells is hard does that make sense because you can't breathe equally difficult is the the expulsion of carbon dioxide and this is where people really get into trouble and sometimes at at our level at undergraduate education we don't do a good job of explaining why is that so a person has COPD bronchitis pneumonia covid no shortage of respiratory problems that's for sure I think we can understand what happens without adequate oxygen we can't make enough ATP but what happens if you can't get rid of CO2 cells are producing it and it accumulates in the blood what new problem have we just created think chemistry chemistry is a PR for this course because we use it a lot especially for things like this CO2 when it dissolves in water what do you get as a result acid yeah so what's going to happen is if you produce carbon dioxide and it goes into the blood where it will dissolve some of it will form hydrogen a free proton which is going to lower the pH of the blood if you can't get rid of that CO2 and it accumulates in the blood you will continue to create hydrogen you will overwhelm your blood buffering system you guys are familiar with buffers for pH help normalize that pH you overwhelm that blood buffering system now you've got two problems you still have the COPD or the bronchitis or whatever lung problem this person's dealing with and you still have oxygen levels that are too low but now you have entered the realm of acidosis and acidosis is low blood pH what happens to any Protein that's in a low PH environment is it good is not good it's very much no bueno it's bad and that's because low PH can start to impact the way proteins function it will denature them they will unfold for example so now we're starting to Trend to many problems so when we think about what does any of this have to do with anatomy and physiology I would say everything I've just given you the blueprint for how people literally die from COPD or an asthma attack it's right here by doing something simple like this so that's why I always encourage people draw this stuff out get down to the level where you can really prove to yourself how this could become dangerous very quickly and then hopefully it becomes more interesting to you and you're starting to see how different parts of your education really have led up to this understanding to something that is a little bit more sophisticated than just yes cells needs oxygen to produce ATP that's an okay statement but you guys are ready for much more so that's why we always go a little bit more back to the notes though let's talk about how metabolism in the cell the attainment of nutrients the production of something else this cellular respiration or metabolism is going to require two sort of subsets of reactions and it takes both of these to equal metabolism metabolism equals catabolism plus anabolism this up so people in the back can see catabolism plus anabolism equals metabolism so metabolism can be broken down broadly into two different categories and I'm going to compare these and then explain how they're linked so catabolism is the breakdown of nutrients like glucose you could break that down into its simpler Parts anabolism on the other hand is building products and sometimes those products may be ATP sometimes those products may be protein something more complex so what we're going to do with catabolism is break down nutrients and release energy and then we'll use those nutrients like building blocks and we'll build products something small like ATP or something large like protein so these are links notice the arrows that sort of cycle I think it's pretty easy to see how catabolism supports anabolism you break down nutrients and you can use the energy to make products why is the arrow feeding back to catabolism what's the relationship there why is it a cycle because as we break down it's anism is used to like create a back up and that same thing that we just built back up get T yep so we could cycle nutrients yeah so we could do that what else might we do could cycle nutrients build products break them back down use the components again I like this answer what does it take to get glucose into a cell what's the process facilitated diffusion do you think we use a protein to do that yeah that's what facilitated diffusion really is using a protein to get nutrients into a cell so it turns out catabolism may allow us to build the protein that allows glucose to enter the cell and those have to be replaced every so often you can't just build it and leave it alone they have to be replaced so there's an example did you have a different one similar okay so it turns out a lot of nutrients that we need from the blood need proteins to get into the cell and so the catabolism brings the nutrients to make the protein in turn the protein allow the cell to get more nutrients so it is a cycle it is a cycle so that's metabolism in a nutshell let's move on to our third requirement for life responsiveness it turns out we have have to sense and respond to all sorts of stimuli being able to sense our neighbor really important it's a true statement now it was a true statement billions of years ago when my formed in cells needed to sense other cells what are other cells doing are they too close to me could they eat me could I eat them so it turns out being able to sense the environment started long ago and likely began in an environment in with a premise of something completely different than what we use it for now but still the heart of it is we need to sense the external stimuli around us that's part of it so when we think about responsiveness our ability to sense and respond to stimuli an easy one to understand is external stimuli give me some examples of external stimuli that you might be responding to maybe right now yeah it's cold in this room it's cold in this room yeah temperature temperature so so external stimuli that's great temperature I'm just going to abbreviate what else yeah light that's great yeah so temperature photons that's what light is little packets of energy perceived by our eyes photons what else temperature and light sound sound yeah sound is another one sound is just nothing more than changes in air pressure pressure that we perceive as sound what about the chair you're sitting on do you like it I don't like those chairs so I'm happy to stand they're not particularly comfortable are they so it turns out you're perceiving this thing called pressure your little sensors in your skin called meano receptors and they're telling you this thing is uncomfortable so I'm just going to keep that very basic and say pressure you're actually also most of you I believe are wearing shoes and none of you seem to too upset about that right now first time you were in shoes you're probably really upset about it right and so it turns out we can sort of tune out some stimuli a lot and some we really don't tune out very well and we shouldn't so these are some examples of external stimuli these are just sort of the basic senses that we use to perceive our environment hopefully none of them are too alarming but we also have the ability to understand really alarming Sensations like capsacin where do you find capsacin Peppers yeah jalapenos ghost peppers on your tongue will tell you holy crap that is hot it's the same receptor that is going to be used for heat so it turns out heat and capsacin Trigger the same sensor in your skin which is why it feels hot anyway you can trick your receptors sometimes we also though respond usually unknowingly to a bunch of internal stimuli that's it's really important for sort of checking in with the body's status the physiological parameters going how are we doing what's the hydration level like in here what's the body tempature like in here do we have adequate blood calcium we have adequate blood pottassium should we change something and so it turns out internal stimuli are also something that we have to sense and respond to all the time if we're going to stay alive it's not just what's the outside environment like it's what the internal environment is like so internal stimuli may include things like I'm just going to abbreviate because I'm short of space BP for blood pressure hopefully everybody's familiar with that BP blood pressure we're always monitoring that we are always always monitoring body temperature body temperature and then we measure more um sort of like esoteric things that are really important to the body but we don't really think about it much maybe like ion level ions sodium potassium calcium these are super important the body is always checking in on those blood glucose is another one blood pH all the parameters that allow your cells to live so long story short your brain right now is having to take in an incredible amount of information in real time external and internal it has to do that and also sort through and filter out the stuff that's not very important like the fact you're wearing shoes or the fact that you're chair is uncomfortable or that maybe it's cold in here over time you become desensitized to it that turns out to be hugely important because that would you ever concentrate on anything if you are always worried about those things that are constant background noise you couldn't and so it is good that we become desensitized to some stimuli there are however some simula that we should never become desensitized to like pain because pain indicates tissue damage and you don't want to become desensitized to that so amazingly the brain has the ability to sort out who important or not important I'm just going to ignore it and that can change based on your um mental status as well if you're really stressed you won't notice some some forms of damage compared to if you were not so stressed so let's talk about why we need to be responsive internal or external stimula so being responsive allows small problems we hope they're small to be detected and corrected quickly Det detect and correct quickly if we can do that then we can prevent larger problems that are more expensive to correct so larger issues are more diff difficult to correct and that has to do with the amount of ATP and time required to correct them correcting small problems in body temperature easy you can even do it by by changing blood shunting patterns send more to the skin or less to the skin easy easy if you ignore that then you're going to have to call in more energetically expensive mechanisms like sweating sweating is hugely energetically expensive we hope that works because after that we're kind of out of options if we're too hot so we're going to always take the cheapest energetically speaking route possible so we want to detect problems before they start it turns out if we look at physiologically your an ically it's the nervous and endocrine systems that are mostly responsible for this the nervous system pretty straightforward I'm guessing you know that's sensing responding interpreting information but the endocrine system also hugely important especially for adjusting blood parameters like calcium or glucose takes both of these organ systems to do the job they kind of work together aot of organ systems sometimes dual actions sometimes redundant actions all right I'm gonna give you a five minute break here and we'll come back the other half of this I will see you at 3:8 I have a clock up here so 38 is the time that I have on this that's when we will meet back it's 303 right now I prom no I didn't but I [Music] [Music] [Music] that's why they still exist I got Y show your handshake last [Music] r [Music] [Music] [Music] so is I'll make it [Music] all right I'm going to get back into it so right at 308 going to get into our fourth crucial life function movement movement so life requires motion continuously and it's not just on the macro scale we're going to have a lot of motion on the micro scale and honestly that's really for amp students more important to think about is what is moving inside of the body and how did it get there so on a macro scale we could talk about Locomotion or movement maybe we could talk about finding food running away from danger so macro movement muscles and bones but I also want to mention micr skill because I think most people when you think motion you think muscles bones but to stay alive we're really talking about how we're going to move stuff around in the body maybe to support those muscles and bones but also all the cells of the body the 30 to 40 trillion cells in the body so on a smaller scale a micro scale motion as we've seen before could be in the form of Osmosis or diffusion osmosis or diffusion across a membrane that is a form of motion and that is definitely essential for life you could also think about circulation or blood flow providing those nutrients such that the cell could get them via osmosis or diffusion we could talk about shunting of heat so the word shunting that might be new for some of you shunting just means movement of a fluid we could shunt blood to the surface for Co we could shunt blood to the core for cold we want to keep warm so we're going to shunt that blood towards the center so shunting of heat is how we move it in the body and of course we move heat with blood shunting patterns is something you'll hear me talk about as well and then we could talk about intracellular trafficking that's kind of a weird term intracellular trafficking obviously the intracellular just means internal to the cell inside of the cell and trafficking is how we move stuff around inside of that cell many things do move with diffusion inside of a cell but a lot of items in a Cell move on little tracks called cytoskeleton and that's a form of trafficking as well so intracellular trafficking could take many forms but we're still trying to move stuff around so back to my original statement up here that life requires constant motion that is true if we look at circulation for example blood flows got to be continuous what happens if it stops and we have something called stasis stasis is the opposite of movement or change stasis is the stopping or cessation of flow in this case what happens to cells Downstream if blood doesn't circulate not good right not good at all they don't get their inputs what could cause a stasis in blood flow a clot for example that would certainly stop blood flow maybe you've got uh an aneurysm where a large blood vessel ruptures that would certainly stop blood flow Downstream so then we can start to see how those are related as well without blood flow you're not really going to be able to do much of the other things on this list so that one's pretty straightforward let's move into something that may be a little little more foreign fifth of six crucial by functions development and growth development and growth and then we'll end with reproduction obviously these go together so development and growth of the human begins with fertilization fertilization and it ends with a process called sence sence is the deterioration of Life function aging we technically known as sence and there's a whole lot of change growth and development that happens in between those two so fertilization begins it if we're talking about a single human and sence is the deterioration of that process leading to death let's talk about fertilization and so here's some terms that I want to introduce to you with a little picture to help make those terms more relevant when we think about Fertilization in humans we're talking about male and female gametes male and female gamet these are single celled life forms shortlived but nonetheless going to contribute some genetics so in the male the male gami haid it is called a that's its name it is haids I'm going to put one in haid the female gamet is known as an oite it is the largest cell of the human body the oite it too is one in haid upon fertilization with a spaty buries into the Zona paluca the little Rim surrounding this oite so the spaty head buries into the zon palua surrounding the oite allows it to stay attached for a while so it can deposit isite material and what we get as a result of that is something called a zygote a zygote a zote is a pretty large singular celled organism it's pretty featureless I'm just going to draw kind of a large Circle and give it a name zyo it doesn't live very long it's about a day and then it will start to just really absolutely take off in a massive rates of growth it will become a morula and a blasticus eventually attached to the uterine lining where it will actually allow the mother to understand she is pregnant so a lot of differentiation of things happen in like about a five or six day period you go through an incredible amount of change you go from a single cell life form a zygote to a morula which has 16 cells and that's going to happen within like 48 hours to a blasticus which has a lot more cells embrionic stem cells develop and then you attach to the uterine W lots and lots of changes happen there and that's just the beginning of it we're really within day five postconception so after that things really take off and we're going to have a lot of new cells created so when we think about the addition of new cells how are we going to do that during this process and after this process because it's not like you stop developing and growing during feudal development it's just really kind of the start of it if we're going to continue need to add more cells renew cells repair old ones we're going to need three things one of these is a very short fleeting process the other two are more common but you've heard two of the three of these maybe you've heard of the first one cleavage cleavage refers to a massive rate of growth of cells from the zygote to morila zygote to morula we're going to get a huge ball of cells that are created but we don't change the size of the actual container and that's due to a process called cleavage so cleavage basically defined as the addition of cells without a change in overall size and that's going to be due to some massive amount of compaction so just a sort of finish this thought this may be kind of new to you cleavage is going to allow a zygote to become a morula which we're going to go from one cell to something that's about similar size I make it a little bumpy because these cells start to poke out on the outside we're going to have 16 cells in here so that's a lot of addition of cells one cell to 16 cells but we don't really change the size of this structure and this is unique we don't see this in the human body besides this particular time period so a zygote is one cell formed from the fusion of oosy and spaite that is going to start the process of an absolute explosion of cells within in about a day we're going to go from a single cell zygote one cell to about 16 cell morula so it's kind of bumpy looking morula is actually Latin for Mulberry You' ever seen a mberry p they everywhere it kind of looks like that anyway mberry morula there you have it from weird fact today so 16 cells and you don't change the size of the container that's an interesting challenge that is due to this thing called cleavage you add new cells but they're so densely packed they don't change in size normally though when we talk about adding cells in the human body we're going to do it with something called mitosis and you've had this before many times but mitosis you're going to go from a diploid cell any body cell diploid or 2 N to another diploid or two n cell so you start and end with the same pyy you're just making a copy of that cell and then meosis meosis is only going to happen in the reproductive organs meosis allows for the production of haid gametes haid gametes and then we're kind of back to where I began which is speratti site and oite so for the vast majority of life we're going to be relying on mitosis and in some respect meosis to produce new cells there's a couple other terms I want to introduce when it comes to the development and growth of cells and you will hear me use these a lot in this class class so I want to introduce them to you now two processes here hyperplasia hyperplasia versus hypertrophy hyperplasia see if I can increase my writing a little bit hyperplasia versus hypertrophy hyperplasia is defined as an increase in cell number an increase in cell number mitosis gives us hyperplasia hypertrophy this is different it is an increase in cell size building muscle cells for examp example you work out that muscle cell gets thicker because of the addition of actin and myosin inside and that's hypertrophy you didn't increase the number of muscle cells rarely after fetal development do you do that skeletal muscle cell does not undergo the process of mitosis when you build muscle you're taking your existing muscle cells and adding to their bulk that's hypertrophy an easy way to remember this is if you compete in something you want the bigger trophy hyper trophy the bigger trophy so maybe that will help you remember these two terms at first so where you sort of get your bearing straight hyperplasia increase in number hypertrophy increase in cell size growth and development last one I want to talk about required for life is reproduction and obviously that kind of goes hand inand with what I've been talking about but reproduction so sexual reproduction provides a lot of new combination of gen that's the whole purpose of it I mean it is an expensive undertaking no matter how you look at it sexual reproduction is expensive from a biological standpoint from a sociological standpoint it is expensive so there's got to be a reason why some life forms do this and others choose asexual reproduction which is just self- reproduction so for vertebrates sexual reproduction allows us a new comp combination of genes with every single person created because as we saw up here speratti site oite those are always going to have small changes in their genome even when they're produced by the same person that means every single person that is born has a new chance of outlasting outdoing outrunning whatever the environment throws at them and so that is a huge benefit to the species it is a personal cost but a benefit to the species so it allows us to outrun pathogens survive changing environmental conditions and should some I don't know plague come through we have a chance of some of us living we don't lose the entire species because of small changes in the genome that allow some people to survive we saw that lately with Co some people were you know absolutely wiped out by it and some people got it and all they lost was their sense of difference in genes and that is true no matter what pandemic we may be talking about that's true for lots of different viruses or bacteria or environmental changes or parasites so this genetic diversity is really a strength of of humans and all vertebras if we were all the same it would just take one virus coming through and write us all out we have the keys to all of our cells different cells different combinations of those locks viruses can't do their job very well this is actually captured in something called the Red Queen hypothesis and this was something that came about in the early 1970s where they're really looking at from an evolutionary standpoint what is the value of sexual reproduction and they came up with this hypothesis which still works today it's pretty genius it comes from the phrase that it takes all the running you can do to stay in the same place which is from the Looking Glass which led to Alice and Wonderland that's a rabbit hole that I'm not going to go any farther down but it takes all the running you can do to stay in the same place that's really a great explanation for why I go through all the complexities of sexual reproduction it takes all the running you can do to stay in the same place it takes every single thing our species has as a unit to not be wiped out by a single virus so I really think that's pretty applicable to why hopefully that explains the whole complexity of it with the significance of it beyond the um sort of sociological standpoint so just to recap these are the things that are required for life not just in a person but as a species and it's a lot it is a lot coming down here wrapping it up with the question you have in front of you if you've got the notes get this to focus there we go before we move on let's think about this this one for a moment an organ looked at different organ systems uh earlier Tuesday now we're seeing how those organ systems came combin and can play different roles an organ can belong to two or more organ systems this is true and it can serve multiple roles like the ones described above think about three examples of organs that do this I'm going to give you two minutes go like dogs three organs have multiple roles for volunte years need Brave so I want to go first an organ with multiple rolls yeah the kidneys and they'll be of the endocine ccat O heavy hitter there yes ma'am kidneys they are part of the well they're part of the renal system so they're going to create urine they are part of the endocrine system they produce quite a few hormones and oddly those hormones help regulate the third system the kidneys are part of which is circulatory or blood flow the kidneys can produce hormones that actually regulate blood flow to the kidneys so pretty potent organs thank you for that kidneys are one of my favorite organs kidneys once you're adult become an adult you have adult knees kidneys and adult tough crowds you got to than you very much yes ma'am pancreas what does it do multiple actions explain yeah what do you think it is part of the endocrine system because it produces things like insulin and glucagon what else is a pancreas tube yeah digestive system great because it produces an awful lot of digestive enzymes who else wants to go brave soul you have to name the organ and explain why you think it belongs to two different systems or functions could be tissue tissue level I if that helps like no that does not help us at all somebody said something skin I don't who's talking it freaks me out thank you I was looking over there her mouth wasn't moving skin what do we want to say for skin nervous system it does contain the nervous system so it's got sensory functions that's great what else does it do immune system IM it has a lot of immune roles thank you very much some of the largest immune concentration of cells are in the skin good job I knew you guys could do it I knew you could do it all right we're going to move on to at least start our next set of notes called environmental requirements for life so the the thought process here was here we're talking about all the organ systems in the body that are required for life so we took a look at what we need to do in order to maintain life but we don't live in a vacuum we are completely dependent upon the environment for inputs and if those inputs cannot be attained from the environment then our organ either have to work harder or we're not going to make it so still on the tour of this thing called the human body which I know you have one I know but you have to sort of think about it outside of yourself um that's kind of the whole point of this is to look at the body from a very different perspective so let's talk about what the body needs from the environment in order to survive some of these are pretty obvious and some of them usually people have rarely thought about because you can't see it and so that makes it a little bit I guess not confusing but a little bit harder to get your head around so we're going to take a look at some main environmental requirements for life we have to have these continuously or we don't last for so let me get myself set up here and we'll talk about how this is going to work so as I mentioned we don't live in a vacuum we have to have inputs to survive so don't live that's good that's a good job iPad keep it up there we go I think iPad gets cranky this time of day so we got to have these inputs constantly in order to survive and the first one I want to talk about is oxygen and introduce you to why we need oxygen which I've kind of already talked about but why oxygen is hard to get in some parts of the globe and what happens if we try try to get it so we we can do okay we don't do great at this in certain environments but we do okay so I'm going to mute this just for a moment while I set myself back up and we're going to talk about kind of how humans evolve in the presence of oxygen we have some interesting adaptations in our body that you take for granted that are the result of us having a hard time getting oxygen for example our biconvex concave excuse excuse me red blood cells that's the result of us having trouble getting oxygen long ago long ago so humans are aerobic organisms and I'm not talking about like jazzer size I'm talking like the need for oxygen and we require a lot of oxygen for really important things that we've already discussed ATP production huge huge huge need got to have that oxygen from the environment get into the blood and then we can produce some ATP we hope with ourselves if we can produce enough ATP then we can sustain Locomotion and by this Locomotion I could be talking about the macro level skeletal muscles moving your body around or I could be talking about the micro level being able to sustain the ATP needs of the heart so that it can pump blood or of the lungs so that they can get air into the body so Locomotion could be macro or micro given what we just talked about oxygen also permits this thing we talked about on Tuesday we are true homeotherms what does that mean can you remind me what that means constant body temperature we don't tolerate much of a range of temperature without getting into trouble part of that is because of the way our bodies are built tall broad also because we're more or less hairless and so that came at a cost we think we got rid of our body hair because of the parasite load ectoparasites like ticks lice for example huge draw on our resources not having the fur that houses those hugely helpful it also came at a cost we have trouble Thermo regulating especially in colder temperatures so always a trade-off but if we can get enough oxygen we should be able to maintain a constant body temperature however expensive that may be so first of all simple question how do we attain Oxygen by breathing what are we going to use to get that oxygen into the body take a deep breath and Ponder this give me a structure that you're using to make that happen lungs getting air into the lungs is going to require some muscles what muscles might those be diaphrag diaphragm that's a great one broad skeletal muscles the base of the lungs when it contracts it flattens and then expands the lungs what other muscles might we be using they're associated with the ribs hint inter Coastal muscles I heard someone say it inter Coastal muscles there internal and external inter Coastal muscles all of these are examples of skeletal muscle diaphragm inter Coastal muscles these are striated skeletal muscle skeletal muscle is expensive to use very expensive to use requires a lot of ATP so ironically the active breathing requires oxygen to produce ATP so that you can continue breathing a strange cycle so how do we attain oxygen breathing but also with skeletal muscle contraction how do we move oxygen in the body what are we going to use for that circulatory system yeah we're going use the blood so we have this funny setup mammals other vertebrates don't have this birds don't have it Birds laugh at us when it comes to breathing birds are way better at it than we are but what are you going to do so anyway when we talk about breathing for mammals we have a complicated system we have these lungs that basically terminate in little air sacks and I'm just going to draw a really basic one right now I could call it an Alvis but that's really beyond what we need to talk about right now I'm just going to say air comes in so oxygen comes in from the outside atmosphere through the respiratory system and then right on the other side of this Alvis this little air sack is a cap AR and in this capillary mammals have the strangest things we have these by convex red blood cells and they're shaped like this you've seen them before no other vertebrate has this shape only mammals have a Bic convex concave I'm always going to make that mist do over by concave red blood cell ER resite what it looks like from the front the top it's not that exciting it looks like a sphere with a little indention but if you were to cut this open and you were to look at it has a really interesting shape and it reveals the purpose of this strange adaptation that mammals have so this is a cross-section of a red blood cell an arthrite so this is sort of the top the cross-section compare that to birds reptiles amphibians fish any other vertebrate and they're going to have something that looks like this and it's much smaller what's the benefit of this this by concave red blood cell shape as oppos something that's just kind of plain elliptical you're close hemoglobin holds oxygen but what to do with oxygen service area everything about our red blood cells with this strange shape which gets us into trouble when we try to get it through little tiny capillaries has to do with the fact that we had trouble getting enough oxygen long long ago when we evolved so did BBS they developed a completely different answer they have bir directional breathing where they don't waste time exhaling they're always absorbing oxygen we waste time exhaling because we're always trying to Exhale so half of our time breathing is spent exhaling that's wasteful so we develop this idea which work pretty dang well when I say this by concave shape with this massive service area allows a lot more efficient oxygen uptake after you can get a lot more oxygen into the cell that spends less than a second at this interface so the name of the game was who can get the most oxygen into their red blood cells in this small amount of time and birds said oh oh we'll do it with our special LS and we're like whatever so we said okay we're going to develop these by shape CU surface area we get a lot of oxygen in here as well and then we put hemoglobin in there increased the amount of oxygen we could carry so it turns out oxygen has a lot to do with how we evolve this weird Anatomy we have these lungs these biconcave red blood cells everything about that has to do with the ability to get oxygen from the environment millions of years ago and you fast forward to today and here we are and we still have this setup which means it's worked pretty well not too bad let get birds but what are you going to do so that's a little bit of evolutionary history about oxygen and why we are shaped this way let's talk about oxygen levels in the environment in the globe so obviously I have a picture of a globe here if we went anywhere anywhere in the United States anywhere on this planet would oxygen levels be the same oxygen levels be some of you are shaking your head no some like M that's a weird question why' she ask that so interestingly the answer is yes oxygen is 21% of the atmosphere all over the globe highest elevation lowest elevation it's still 211% still 21% everywhere Manhattan Kansas what's the elevation of Manhattan Kansas right now you are currently sitting at an elevation of about 1,000 ft so it's not sea level right we're not sea level we're not that flat so we have some elevation 1,000 ft above sea level but it turns out oxygen levels are 21% of Earth's atmosphere all over the Earth that includes sea level all the way to the highest elevation so some of you are like but wait wait wait wait when I go up to a mountain I have a hard time breathing I would say you're right most of us do but it has nothing to do with the level of oxygen has to do with atmospheric pressure and these are different oxygen and atmospheric pressure related but still different the majority of our atmosphere one reason why it's hard to breathe is because every time you breathe in the majority of the stuff you breathe in is not even oxygen it's nitrogen about 78% of our atmosphere Every Breath You Take is 78% nitrogen you can't even get that across the lungs and into the blood you shouldn't unless you're a deep sea diver and you come up too fast and then you get the bends but majority of what you inhale is nitrogen gas and you can't use it so automatically we're sort of hindered by oh dang I can't even use most of this so now we're back to 21% is oxygen when we think about nitrogen getting into the blood from the lungs can't do that unless we have a lot of high pressure that's going to happen if you go scuba diving without the scuba or if you fly really high without pressurized cabin nitrogen generally useless oxygen fickle because it's not the majority of our atmosphere and we also have the problem of our red blood cells only spend about a second passing through that interface between the lungs so so what it turns out to have at the heart of it why is it hard to breathe at high elevations it's not because of oxygen amount it's because of this thing called atmospheric pressure atmospheric pressure is our enemy in many instances where you blame low levels of oxygen but instead it's atmospheric pressure parting s atmospheric pressure is higher or lower at sea level this is a parting question atmospheric pressure higher or lower at sea level compared to top of mountain much higher yeah sea level has the highest atmospheric pressure it gets lower incrementally as you go up in elevation for reasons that we'll talk about on Tuesday so let me know if you have any questions please remember to take your quiz available to you tomorrow 5 video is posted tomorrow at 5 as well have a good weekend