majority of why we need oxygen we talked about how you know oxygen actually is 21% all over the Earth what really changes is um atmospheric pressure which we're about to move into we actually require pretty um high amounts of atmospheric pressure to to function we also talked about how the majority of our atmosphere isn't even usable you know the majority of our atmosphere is nitrogen nitrogen gas and humans really can't get much Nitro gas into the blood across the Alvi and the lungs it it's not very soluble so it doesn't move across that membrane very well um so interestingly Every Breath You Take 78% of it is nitrogen and automatically taken off the table as far as usability uh you also get a little bit of water vapor some carbon dioxide argon helium there's a lot of stuff we can't use but 21% oxygen uh and so when we think about what are we going to do with that oxygen obviously cellular respiration um as I ended with I think on um Thursday under most conditions we can't even get nitrogen from the atmosphere even if we were to take a deep breath and 78% of the gas in these lungs nitrogen we can't even get it into the blood unless we're under really high pressure I'm not talking like deadline pressure I'm talking like you dive deep into the ocean without any scuba on any scuba diving gear on and you encounter a lot of pressure that will actually drive that nitrogen gas into your blood if you come up too quickly you will suffer from something called the bends and the bends occur when you have a loss of pressure really quickly and this nitrogen that has made it into your Blood Bubbles and it comes out and it actually settles into your joints your joint cavities like your knees some of you're going oh it feels awful that's what leads to the bends it causes people to bend over in pain it's because they have nitrogen bubbles that have settled out of solution basically and found their way to their joint capsule so I can't imagine how painful that is but there you go a little bit of fun trivia about nitrogen uh and why it's called the bent but we're going to move on to our next um sort of topic here which is atmospheric pressure so we're going to talk about how humans uh evolved more or less at sea level maybe not at the sea but we still evolved at sea level which means we're really dependent upon a pretty good column of air pressure pushing down on us at all times so that we can get oxygen across the Alvar wall and the lungs and into the blood so we actually rely on the atmosphere for a lot it's not just oxygen it's how much pressure is being donated to our cause to get that oxygen into into the blood so let me kind of rearrange this and um kind of zoom in a little bit let me see if I can get this to cooperate a little bit more it's been a little finicky today in my other classes it's kind of um the iPad didn't really want to participate in class so I'm always kind of fighting with this thing asking it hey remember you still got a job to do so let me see if I can get it to focus there we go so when we think about atmospheric pressure it is sort of that um it's hard to observe you feel it it's hard to observe so we don't think about it but it substantially AIDS in our ability to breathe it's an invisible thing it's this invisible force that is hugely helpful for breathing so atmospheric pressure you really don't notice how important it is until it's gone you don't miss something until you don't have it and you're like whoa kind of needed that so humans evolved at or near sea level so elevation just called sea level where pressure is high for terrestrial animals like ourselves we find the highest amount of air pressure at sea level now if we were a marine mammal and we could dive really deep into the ocean we would encounter a lot more pressure but none of us in here appear to be SEALS or walruses or any of those mammals that can Di really deep and do quite well so for us we're going to say hey we're air breathers we're terrestrial organisms we're going to say sea level is the is the lowest elevation where we can survive at and at sea level life is easy for us and that sort of helps us understand we probably evolved at an elevation near or at sea level a lot of what we depend on from the atmosphere is found more or less at sea level so air pressure atmospheric pressure is highest at this sea level again sort of thing about that is our home base at higher elevations if we start to move up this sort of fictional Mountain that you see there we struggle we struggle a lot if you've been to high elevations you felt it if you pretended not to feel it and went out and tried to exercise you really felt it you can get into danger something called Mountain sickness elevation sickness it's a whole sort of cluster of problems that can make you very sick it can be fatal um so it's not something you should ever ignore but just to kind of paint the picture of why does atmospheric pressure change so much why is it so much harder to breathe at different elevations I'm going to uh take us on a little trip we're going to start at sea level uh we're on spring break things are pretty good uh and so we're going to be this is um some pretty awesome uh drawing here pretty technical stuff so this is you you're at sea level I know you're pretty happy um so because you're at the beach and so things are good you're obviously enjoying life at the beach and you have no worries at all about breathing you don't even thinking about it because above you is this invisible but for us not so much invisible column of air and this is air pressure and at sea level we have the most air pressure the tallest column above it and that is working like a driver to help us get oxygen atmospheric gas into our lungs we don't really think about it because we take it for granted similar to Kansas what's our elevation here thousand at a thousand yeah good job thousand so that's pretty close to sea level not at sea level but pretty close so we don't really notice the effects of atmospheric Lo loss of atmospheric pressure here in this but let's say that you're like you know what I'm kind of bored at the beach I think I'm going to take a trip up this mountain here it's really neat up there and so you start to you know sort of asend up this mountain and at first you're like hey this is pretty cool I thought I'd be like really sucking wind but I'm not I'm feeling pretty awesome and so you keep going and about here so you're really big because I can see you from this elevation um you're like I think I might have made a mistake you're about to fall off the mountain but before that happens um you start to notice it's really hard to catch your breath you feel tired your heart's racing your respiration rate is up you could get confused you could have lethargy probably suffering a little bit from dehydration reason being for at least some of that is above you in the stratosphere is a much smaller colum of air and that's because you went up and as you went up the column of air above you got smaller because you went up you have less help from the atmosphere getting that oxygen atmosphere gas into your lungs you don't really notice it until you ascend too quickly and then you're like oh this is not good so it turns out humans like many anals really love here there are some populations of humans that be pretty good at high elevations that they evolv there they lived there for eons generations and we can see these changes that make it easier for them to function at high elevations in their Anatomy just their gross anatom is different usually a little bit shorter than the average person they are Barrel chested not I'm not talking about weight I'm not a put down just in general instead of being sort of rectangular shaped they're kind of square shaped especially in the thoracic cavity what benefit does that provide given these challenges I've talked about that somebody said I in here they have the ability to inflate the lungs more so they can actually create more negative pressure so when you inh inhale just I'll try it this like a devil is a yoga course right now to inhale you're actually inflating the lungs which decreases the pressure in the lungs that allows air to come in the larger you can make this container that we call lungs the more negative pressure you can create and negative pressure sucks air in if you're a lowlander like you know we are here generally we don't have the ability to expand the lungs as much because our thoracic cavity seres as sort of a limit like no the ribs that's all we're going to get so some populations of humans are really good at higher elevations because they're anat is different but you're not going to get that in one generation you're certainly not going to get it in your lifetime what's the best thing you can hope for in your lifetime you go to a top of a mountain you're like I'm going to live here and about four to six weeks you noticed it's a little bit easier getting around what happened in your small amount of time that you were there yeah your body is just starting how to more efficiently use the oxygen that you do it is getting better using the do you have how is it doing that give you some Anatomy or physiological processes that have changed in the small amount of time that you've been there yeah blood cells more red blood cells that's a great answer yeah you can actually increase the amount of red blood cells or erthrocytes that is due to a hormone and interestingly that hormone is initiated by activities in the kidneys who would have ever thought the kidneys are like wait I don't think we have enough ox o we should release a hormone that fixes that the kidneys tell the bones you should make more red blood cells in in a small amount of time you will good job there what else might we do what do red blood cells contain hemoglobin hemoglobin so we're actually going to increase the production of hemoglobin as well you can also see a little bit of an increase in plasma volume the watery stuff that moves blood around important because if you just added blood cells and you kept plasma volume the same what would happen to the viscosity or thickness of blood you add cells but you don't add an equal amount of water viscosity or thickness as they go up or down it goes up your blood gets too viscous and that's dangerous it's going to cause a lot of workload on the heart which is kind of already having trouble but now you're having trouble profusing your cells with all these cells that contain oxygen so we you see a lot of physiological changes that can happen in a person quite quickly and that's called a climatization and it's a huge benefit to us whether you're in the mountains or studying it because it really helps you see how different body systems work together and how the different levels cells tissues organs have to also function together to get something done the opposite is you don't have the ability to survive in that environment and you're going to have to go back down to the ocean where life isn't probably quite so bad all right so putting some numbers on this some people are numbers people I'm going to talk about what we measure atmospheric pressure in we can measure it in millimeters of mercury that's what I generally choose to use we can also measure it in something called an atmosphere which is strange the unit of atmospheric pressure is atmosphere it's like they just ran out of words so like I don't know it's 5 o'clock on Friday just call it atmosphere B I don't know but I use millimeters of mercury but you could see atmosphere at sea level easiest for us to breath we're going to look at 760 mm of mercury or one atmosphere if we so enjoy our three-day weekend we're going to go out to Colorado let's go to Denver we're going to see oh it's kind of hard to breathe out there 640 mm of mercury we've already lost quite a bit of our air column above us that's making it easier to breathe if we decide to keep on going go to Mount Everest top of Mount Everest 250 a Mercury most of us would need supplemental oxygen air flow pressurized air just like you would in a jet pressurized air flow helps you get that air into lungs so long story short Evolution where we came from still impacts sort of our abilities today because that's how we were designed so this question now why is it so hard to bre Elation assuming you're not climatized to it before this little bit of information many people might have said there's less oxygen that is not true how much oxygen all over the globe 21% all over 21% what changes is the pressure and the distribution of those oxygen molecules and that has everything to do with of mercury we will revisit this substantially when we get to the respiratory system which is kind of towards the end of the semester we'll see these same play out in people that have diseases like COPD which is a cluster of things they can't create negative pressure so every day for them is like living in Denver when they're not acclimated they can't create negative pressure they can't get that atmospheric gas in the lungs and they can't get oxygen into the blood it's the same this is this is a lot easier to understand because you probably experienced it or we can make a simple drawing but lung diseases kind of recapitulate this problem that we have of we can't create enough negative pressure to get atmospheric gas in okay let's talk about other things we need from the atmosphere or not the atmosphere just the Earth in general to survive so I'm going to blank this for a moment while I get iPad cranky iPad up and going we're going to talk about temperature that's where we're going next and temperature I feel like when we talk about temperature either in the dead of winter or the heat of Summer It's really impactful because we're suffering through it right now especially when you have to to walk across campus we just like hot and sweaty when you get somewhere um so we're going to talk about all the things that your body is doing to try to Thermo regulate in this difficult environment sometimes Kansas likes to throw challenges at us when it comes to Thermo regulation so we're going to look at something called temperature and then I want to relate that sort of a really important physiological principle called thermal neutral zone humans have really just kind of a pitiful Thermon neutral zone it's super small other animals laugh at us I think consistently because we're either too hot or too cold We are Never Satisfied if you have roommates and you share a thermostat you know exactly what I'm talking about one of you will turn it up one of you will turn it down constant battle and you get that energy bill you're like you know what we just don't need air conditioning at all we're good we're good I had no idea it cost that much so we've all been there we learn how much ever money really takes um so we're going to talk about why is that why do we have such a pitifully narrow range of temperatures that we find to be acceptable and what happens if we can't manage this core body temperature so when I talk about temperature I'm talking about core body temperature I'm not talking about surface skin is allowed to vary widely in temperature think about how cold your ears and nose get in the winter they don't really get a lot of thought as far as the body's concerned for tempature when I talk body tempature I'll be very precise and specific about this throughout this course in human body too we're talking about core body temperature so what is the temperature of the vertebral column the brain the viscera that's what we pay attention to the rest of it good luck to you within you know within we don't want you to have frost bite but we see a huge range here so we're going to talk about what happens if we can't function what happens if we can't maintain these temperatures so narrow temperature range and that is due to several things first of all we lost our fur coat long ago I'm not sure anybody misses it but we're basically hairless right so that was again to get rid of ectoparasites reduce tick SCE those kinds of things and mostly were like that's good we don't want that so that really reduces our ability to Su regulate so that's Thing One Thing Two is everything about the human body is designed really to lose heat we are broad bodied we catch a lot of wind and we minimize sun exposure and that also has a lot of evolutionary significance to it we evolved to be long distance hunters and before you get too excited like yeah we ran that down we ate it let me back up a little bit we dominate in the Olympic category of speed walking now we think our ANC cestors were the most efficient at speed walking probably not running but speed walking so we literally chased on our dinner by walking it to death and I'm not sure if it got tired or just gave up out of boredom like just ended already that everything about the flip posture of the human foot tells us we're really good at speed walking so I Wish I Had A better ending to this like hey we were awesome Runners and now look at us no we're speed Walkers so get good with that but that's how we evolved and thing about our body plan says let's minimize sun exposure in a hot climate where we likely evolved and maximize wind exposure so we can keep on trkking and bore dinner to death and it'll just give up and we can eat so that was good it worked well for us but we are really meant to lose heat so that's okay in a climate like like today but thing about January in Kansas and you just can't warm up your body plan or in German the bow plan is working against you so we have a really narrow range of temperature and we spend a lot of energy trying to manage that temperature let's talk about what happens if we can't so our cell processes are really what we're trying to manage here it's not just Comfort it's let's make sure our cells don't spin out of control or stop functioning if a cell is too cold what happens to it that's really pretty detrimental it's a cell so we're not talking Comfort what processes are disrupted if a cell is too cold it's so basic people don't want to say it you're like that can't be right it's too basic okay so it's diffusion diffusion does not work well in cold temperatures because diffusion is based on something called Brownie and motion have we heard of brownie and motion Brownie and motion says particles are in random movement all particles air particles water particles doesn't matter random movement that's called Brownie and motion let me introduce that term to you Brownie and motion is really the secret to life if anybody asks you what's the secret to success you should tell them brownie emotion that's it that's the whole thing because if you don't have it you you die so the secret to success literally is brown and motion so what is this thing that's so important so browni and motion uh says that you know particles no matter what they are I never draw things perfectly round because many things in nature are not round um so it's not just that I've had a lot of caffeine which I truly have clearly but it's not just caffeine so here's some particles I'm going to give them a fancy name and call them solutes these are in motion all the time they go in all different directions until they bounce off something else and they turn around and go the opposite way this is the principle of diffusion how are we going to get things from a concentrated area to a less concentrated area I bet you've seen this before if I introduced a semi-permeable membrane and I said these holes in this semi-permeable membrane allow these particles through and I said here's container a and I said here's container B and then I asked you what happens to the distribution of particles over time what is the answer something you've answered many times before in the past what do we reach equ equilibrium that is correct how did that happen Brownie and motion Brownie and motion is how particles solutes move random motion all the time this only works in certain temperatures effectively if it's too cold what happens to motion and that's okay if we're just looking at something like this but in a cell if we slow brownie in motion to the point where oxygen deliver is too slow glucose deliver is too slow we can't get rid of carbon dioxide what happens to that cell's ability to live goes down to the point where maybe it doesn't so it turns out if we are too cold if we are too cold the problem is brownie in motion slows I don't want to say stop because how cold do you have to be for motion to stop somebody said it say louder like absolute zero would probably do it most of us are not absolute zero - 273 Kelvin that' be cold that'd be cold probably not come back from that so brownie in motion um slows and it's so slow you can't access can't get nutrients into cells you also can't remove waste but nutrients probably what's going to do that cell in so Browning motions going to slow think about this little sort of diagram down here two slow not going to move too hot what's the problem with being too hot from a cell's perspective you interview the average cell in the street walking down the sidewalk hot yeah so what's the problem with being too hot and the cell says Den say it louder Den proteins nature proteins too much brownie in motion will denature proteins the protein denatured what does that mean yeah you lose its structure it comes apart in a Cell in a biological entity once the proteins denature does it come back no it doesn't so you're done and most cells are made of protein and enzymes are protein so cell life stops because it's too hot so we have interesting structures inside of our cells called chaperon proteins which sounds a lot like it does when you're in junior high or prom chaperons but here chaperon proteins come and find a protein that's struggling and it gives it like a giant bear hug and says it's okay I'm going to help you out and that works as long as you have enough shaper room proteins or they themselves haven't been denatured but too hot you'll denature everything and it won't matter so it turns out you denature proteins inside a cell and that cell dies so I hope I have at least convinced you on a you know fairly um quick level why we need to be at a constant body temperature we sort of the goldilock principles you can't be too hot and you can't be too cold either way your cells suffer so let's talk about how we could map this this thermal neutral zone so I kind of talked about tempature let's talk about thermal neutral zone ours is like really pitiful I think other animals laugh at us but you know we probably get them back in some way or the other so when we think about thermal neutral zone let me introduce this to you energy in the form of ATP is what we need to maintain Core Body tempure this denotation here T subb if I haven't introduced it already paper right T subb this is the uh denotation that you see for core body temperature so t for temperature uh the subscript here means core core body temperature so true homeotherms like humans have the ability to crank up ATP production and use just to maintain core body temperature and we're going to do that if we're too hot or too cold they both are energetically expensive and it's probably easier to understand that if you've been too cold you go inside and you just feel like you can't eat enough you probably don't experience that hunger drive when you're too hot but you're still using a lot of energy not eating when you're too hot is very beneficial why is that what happens if you're really hot and you eat a lot of food have you tried this yeah is it good you feel terrible so that's the least of your concerns that you feel gross what can actually happen if you really hot and eat a big meal you think eating creates heat friction of food along the digestive tract creates a lot of heat enzimatic digestion of your food creates a lot of heat so if you're too hot and then you also eat what you're doing is just adding to that heat load and that can sort of kick you over the edge of going from uncomfortable to uh oh I I now actually have a medical problem so you don't want to eat if it's too hot so let your body tell you hey don't do it it doesn't feel good so it turns out either way too hot or too cold we're going to crank up the ATP production and use just to maintain core body temperature ideally we stay within so there's my short hand if I haven't introduced this to you ideally we'd stay within what's called our thermal neutral zone or tnz thermal neutral zone so many physiological experiments went into figuring out what is the human Thermon neutral zone the information we have mostly comes from young men who enlisted in the Army so I don't if you familiar with the Army but maybe some of you've been in the Army but they like to use their recruits for all sorts of purposes in figuring out thermal neutral zone was one of them to get this they took a healthy young male about age 21 many of them to get accumul data put them in a room on a metal chair no clothing and they wanted to see what temperature did they become too hot or too cold and so it took a lot of time actually to figure this out because everybody's got a little bit different and then they as the Army does experimented a little bit by misting them putting a fan on them what happens to ATP usage if we just introduce little environmental Challenge and either way too hot or too cold metabolic rate went way up way up and so that's how we kind of got to know what is a thermal neutral zone from those kinds of experiments now with the Army interested in pure physiology maybe but they're probably trying to design better like equipment for soldiers to use when they went into to battle so that's where a lot of our science information actually comes from stuff like that so in the thermal neutral zone that's what we shoot for here in our Zone ATP usage is really minimal we don't use a lot of energy to maintain our Poe Body temp mature and the reason for that is the heat that's produced from metabolism or blood flow in friction is matched with the dissipation of that heat equally from the skin so we produce it in the core and we lose it from the skin at an equal rate that's our thermal neutral zone we produce it and lose it at an equal rate and we don't have to put any effort into either one but we have a really small one so let's talk about a Thermon neutral zone this is something that is helpful for healthy humans this is something that's helpful for those of you going into athletic training this is helpful for those of you going into maybe you want to be a a neonatal Intensive Care Unit specialist babies have a horrible time with this as do older people there's so much that we can get from a graph like this and we could apply it to different situations an athlete that's working too hard in the heat a newborn baby an older person someone that has cardiovascular disease so you see this a lot it will definitely make an appearance on the exam because it explains so much physiology so I'm going to give you a moment to think about this I will explain it a little bit on the X AIS I have something called T sub A A is for ambient Ambient is the Environmental temperature so T subb is core body temperature T sub a is ambient temperature or environmental temperature what is a temperature right outside of your skin that's ambient you can think of that is environmental but we call it ambient on the Y AIS we have metabolic rate ATP production and because we are true homeotherms we can alter that ectotherms frogs Turtles fish they can't do that so they have a really kind of hard time in the cold you ever seen a turtle in the cold Mo really slowly it's because it can't crank up the furnace so we're really lucky that we have this ability because we can explore new habitats we can go out in the cold or the heat and more or less manage ourselves this is not true for all humans though especially those that are older newborn babies those that have disease they cannot do this so if you work with someone that has had a previous heart attack and be work in a clinical setting you should tell them you you need to avoid temperature swings have you heard this cardiovascular helps people have heart attacks you really can't go out into mature swings why is that because everything here requires more ATP which requires increased heart rate if you've already had a heart attack that's the last thing you need is a sudden spike in heart rate there's so much that can be gleaned from this particular graph so when we think about how to read this graph how to use this graph I'm going to start in the middle and the dotted line here 25° C to 29 9° C this is the ambient or environmental temperature that we call our thermal neutral zone so the human thermal neutral zone this is an unclothed person sitting in a room with no air current so it's just you and the pocket of air that surrounds you so this is sort of like uh just raw data so our Thermon neutral zone is only 4° C let's talk about if we're too cold if a human is too cold what happens to metabolic rate well it goes up and it goes up pretty quickly why is that what are we trying to do trying to make heat how do you think we're going to make heat shiver yeah somebody said Shiver I like that so if you're too cold one of the things we will do is shiver and shivering requires skeletal muscles to move their contract proteins which are actin amiin violently and really quickly past each other and that creates friction so that warms us up but it comes at a huge cost because you're running your skeletal muscles and skeletal muscles are expensive so shivering is hugely expensive the other thing we'll start to do is we will shunt or move blood where do you think we'll move it to the surface or to the core core to the Core try to keep hot blood as close to the core as possible because those are where the organs that really matter reside shunting blood changing the blood shunting patterns that takes energy because you have to use smooth muscle to squeeze some vessels and slow flow to the skin it to dilate other vessels increase flow to the skin or excuse me to the core so that all takes a lot of energy and these are just a few examples but it takes a lot of energy if you're too hot it also takes a lot of energy and your metabolic rate goes up why what are you going to do that's energetically expensive if you're too hot remember this person is sitting in a room they're not moving somebody said it sweat yeah so humans possess Ean sweat glands erran sweat glands produce a lot of sweat for evaporative cooling but that takes a lot of energy so you will sweat what else might you do it's the same as two cold but opposite direction you're in shunt blood yep shunt shun blood probably do that first it's cheaper than sweating but you're still going to use some energy you're going to move that blood towards the surface for a heat dissipation so that's a lot of energy either way we hope we can stay in that thermal neutral zone again thermal neutral zone defined as heat production just through basic metabolism basic friction like blood flowing through a vessel that creates friction heat production equals passive heat release just through diffusion so thermal neutral zone that's what we want to do give you a little break here I'm going to give you five minutes I'll meet you back here at L 3:15 315 for your break [Music] okay can I ask you a question sorry um so talk about when you're adj higher elevation when you make the adjustment from going high low what's your body doing respon okay why you train elevation that only works for a couple weeks because you don't need that much oxygen your body body just yeah it can um it increases blood pressure because you're trying to move your cells which increases workload on the heart yeah all right that's the same as injecting um EPO blood doping that so athletes like Lance AR got in trouble thing that's what that is he injected a compound that then him on that does that okay great athletic advantage totally illegal and if people do it they too will get physiologically because super you'll lose it in a week you get a little bit of in the first couple weeks which is why athletes train at iations and that's totally fine there event better be right okay gotcha and then um the B Be motion is that how you brownie in motion Brown yeah like brown Ian okay you said it was the bouncing of molecules off of one another yeah just random so they'll go until they hit something and turn around and go back perect what is your name laen what's your major I'm bical engineering oh good yeah then minor in math and hopefully biology soon but we'll see come on to the good that's what I'm that's what I'm gathering [Music] okay for [Music] [Music] okay welcome back continue here sort of the last lar envir we need obviously nutrients and water got have these constant inputs humans need a lot of food because we are again relatively speaking on the scale of animals on the planet there's a lot of them that are way smaller than us remember insects are also animals there are a few that are larger but relatively speaking we're kind of towards the larger thing so we're going to need a lot of nutrients and nutrients are measured in something called K calories kilo calories kilo calories we need about 2, 2500 on average for the normal adults just me so that can vary widely depending on activity level growth um obviously athletes need a lot more professional athletes but average person so we need those kilo calories for again sustaining cellular processes like metabolism grow need it for immune function immune functions rely on proper nutrients so that's a pretty General list but got to have these things and they all require ATP in order to make sure cells have what they need these nutrients and this water so they can make ATP we're going to have to make sure the blood actually is densely packed with nutrients and still capable of carrying off waste so when we think about what this blood does as cells I've mentioned this several times already I feel like this point was not made strong enough last semester so that's why I'm being hyper clear blood doesn't just deliver nutrients takes away waste products and byproducts and that's really important so don't forget that part of what blood does so when we think about nutrients and water though that's really delivering input to cells nutrients and water going talk about how we could classify these nutrients and this is pretty broad but still pretty important and then I'll end with sort of a thinking question here I can get this to cooperate so when we think about nutrients nutrients we could broadly classify nutrients in three different ways we could classify them as macro micro and then we have this weird category called water and some people say water is a nutrient some people say water is not a nutrient because it doesn't have calories so I just put it in its own what do you think a macronutrient means macronutrients what do you think that means macro think you need in large amounts or small amounts large amounts we need large quantities of these daily so a macronutrient means we need a large quantity daily and macronutrients include things you've probably heard of like carbs fats proteins these are the macronutrients carbs fats and proteins you need pretty good amount of those every day micronutrients obviously viously you need a smaller quantity these include things like vitamins I'm going to abbreviate minerals vitamins and minerals they help with the process of ATP production they might also serve as uh free radical scavengers vitamin B vitamin E beta katene these help us scavenge free radicals so micronutrients smaller quantities but still very important vitamins and minerals water I don't know that I need to really explain water in the first world in Western diets we are usually somewhat chronically dehydrated as a population and our blood is a little acidic so most people need to drink more water um so um water of course important for Thermo regulation why do we need water Thermo regulation you're not going to regulate very well if you're dehydrated that's because you lose blood volume and if you lose blood volume then you can't shunt blood you can't move heat heat moves via blood you want to move heat you move blood not enough blood not going to move heat I gu everybody's drinking water right now so that was your water reminder it's time to drink water um also water is needed for um diffusion diffusion or the movement of solutes in the body that's a water-based process water is the medium that solutes use to move so just some basic stuff about water nothing too Earth shattering there I do want to end with a sort of a question for you though can a person be overweight yet also malnourished y absolutely so you're shaking your head right away yes they definitely can person can definitely be overweight and malnourished they might be eating the wrong things so they have nutrient deficiency but they still could have too many calories for example um let's talk about sugar you think Americans eat too much sugar yeah yeah we eat a lot of sugar so the average adult evolve to eat about 10 pounds of sugar per year the average adult evolve to eat our our ancestral diet our native diet 10 pounds of sugar a year how much sugar you think the average adult now in the United States consumes per year about 100 pounds a year it's an order of a magnitude more than what we evolve to eat we evolve to eat 10 pounds a year average adult eats 100 pounds a year so does that contribute to this overweight yet malnourished definitely so you think about how much sugar the average person consumes it's not hard to see now why diabetes like type two diabetes is usually one of the third leading causes of mortality in in this country it's because it's just too much sugar we never evolved to handle that much sugar other animals have but not not us we are not meant to e that much sugar but sugar is available and so it's really hard to criticize because what's available and accurate if you're hungry a vending machine what's in there you're going to find broccoli and kale nope you're going to find different forms of sugar in the form of high glucose High um corn St for example so no shortage of bad food options okay here is a thinking question I'm going to let you chew on for a couple minutes before we move on I can't fit all this in there so if you've got this printed that's good if you have someone next to you that's got it printed you could maybe ask them nicely you could look off of their notes so about 50 million years ago large mammals began to evolve this was also a time when the Earth's atmosphere so our oxygen levels were at some I wish I could fit all this in really can't some of their highest levels so when we evolved we had some of the highest oxygen levels about 23% now we have 21% just to put this in perspective so mammals require large amounts of oxygen just to move around and we evolved at a time when there was a lot of oxygen so we got to have this oxygen too maintain metabolism and fuel brain functions so we need a lot of oxy oxygen maintain metabolism and brain functions additionally a million mothers use up to 60% of the oxygen in their blood before it gets to the placenta and the placenta is how the fetus in the womb connects to the mother's blood supply to get what it needs so the moms use a lot of oxygen before it even gets to the placenta so more oxygen in the air would have contributed to more or better conditions in their womb so this turns out to be kind of an interesting evolutionary uh relationship between our atmosphere long ago and our ability to sustain ourselves and pregnancy so what is it about oxygen why is it specifically needed in the body how is it transported what happens to our ability to intake adequate amounts of oxygen at high levels so these are all things we've talked about I put this on here because this is an example of kind of some questions you may see on the exam and people always want to know what's the format like I've talked about the format I think people in this class are far more sophisticated than just regurgitating information in the exam I'm not going to ask you list the three macronutrients that's not useful what's useful is being able to use that information so on the exam you might see sort of a scenario based question like this and it may have answer possibilities that are all wrapped up and directly related to what we talk about but I want to see if you can sort of tease apart why it matters so just a heads up when I put questions like this on these um sort of the bottom of these notes don't just blow through them after class take some time and go through them it will it will help you on the exam and if you don't know the answer like this one's pretty obvious because we talked about it if you don't know the answer it's fine all it means is ask me you can ask me in office hours you can ask me an email it doesn't matter you just got to ask me so just a word to the wise there at the bottom but for us we're now moving into homeostasis in the interest of time so we're moving away from this particular set of notes moving into how are we going to maintain this giant human body with all this energy and all this oxygen and all the cool stuff that we have access to so this process of homeostasis is really Central to physiology many physiological experiments did not go the way the researcher had intended because of homeostasis it is hard to dislodge an animal or person from homeostasis especially when you're researching it's like why why didn't that research animal leave its homeostatic range so that I can measure it many physiological experiments have been undone because homeostasis is just so wellmaintained so the reason why this is important not only just because it's a central theme to physiology and human survival it's because if you understand the goal of homeostasis which is to maintain the internal environment you can start to think about how different diseas is pick that apart and systematically kind of ruin our ability to maintain this steady environment that our cells rely upon so let's start with kind of just a basic definition what is this thing called homeostasis there's a lot of really fancy definitions this one works for us because you're going to see me use this a lot so I like simple and straight forward so we're going to talk about homeostasis as the maintenance of the internal environment maintenance of the internal environment internal environment is likely not what you're thinking it's not everything inside the body there's a lot of parts of the body that are not homeostatically regulated there's some parts of the body that are very very carefully regulated we'll talk about what does the internal environment mean before we get there though let's talk about the goal the goal of homeostasis is for the internal environment to remain steady over a period of time the internal environment to remain steady over a period of of time so when we measure homeostasis we're not looking at a single time Point that's not very helpful we need to look at 24 hours or 48 hours or six weeks because things sometimes fluctuate on different time scales so time scales are really important when we think about physiological regulation but overall we want to see these environments and some variables remain fairly constant if we can maintain steady internal environment then we should be able to provide the cells of the body 30 or 40 trillion of them with whatever they need to be healthy if any of this falls apart we'll start to see cells suffer so back to that set of notes earlier about levels of organization if cells suffer how much of that organizational chart those clades fall apart you lose cells what happens to tissues they don't do so good lose enough tissues what happens to organs they don't do so good lose enough organs you lose organ system so we're still back in the interconnected sort of levels of life and it all comes down to did you maintain homeostasis I feel like it's a personal question so you don't have to answer it you could ask your roommate did you maintain homeostasis but we're really looking at how organ systems in organs provide the internal environment that allows cells to thrive and if cells Thrive then the organ thrives so it works both ways so well-being homeostasis let's talk about internal versus external environment internal versus external environment so remember I'm not talking anything inside the body and anything outside the body that's not a very sophisticated or accurate definition when it comes to homeostasis so let's talk about internal versus external environment I'm GNA start with internal and then I'll move into external so when we think about internal environment the internal environment provides cells the inputs and waste removal that's required for life so the internal environment is what directly nourishes cells and removes their waste so with this hint what is the internal environment or would you say sort of anatomically that includes blood good there's there's a good start blood specifically the plasma and there's only one other area that this pertains to easy to ignore but please don't what directly bathes all the cells in the body directly B what are they sitting in extracellular fluid it's this fluid Mass that's so easy to forget and it's so important if you don't have enough of it or you don't balance the composition cells the diffusional gradient between blood and cells is messed up we have to manage that extracellular fluid it's also called interstitial fluid but extracellular fluid allows us to abbreviate as ECF so that's nice as far as homeostasis is concerned managing cells of the body that's what we're trying to manage five lers of blood and a whole bunch of extracellular fluid how hard could that be really hard really hard it'll take all the ATP you have some days just to get that done so that's what extracellular fluid and blood comprises the internal environment external environment believe it or not is not managed as part of the homeostasis external environment not managed as part of homeostasis so external environment doesn't just include anything outside of the skin in fact that's not even figured into this equation so external environment is anything that is outside of the blood and extra fluid so tissue masses for example that would definitely be external environment uh Lumen of the gut tube Lumen of the respiratory tract all of those things are external environment we don't regulate at them as part of homeostasis we allow them to fluctuate widely so external environment not part of homeostasis to put this together some sort of visual I'm going to put some cells here I'm going to go Bob Ross style happy little cells happy little cells and they're going to be living in a happy little environment we'll talk about what does it take to maintain them so if I introduce a group of cells and a blood supply that feeds it's pretty easy to understand why the blood supply is important because that's where oxygen glucose comes from but there is a little bit of fluid in between that blood and those cells that also has to be managed and that's why the extracellular fluid environment or ECF is part of what has to be managed as part of homeostasis so never forget the value of this extracellular fluid component putting this in perspective if you've ever suffered or worked with someone in a clinical setting that had edema em a edema what is that edema just a collection of fluid you know maybe their ankles were swollen maybe they had some sort of swelling somewhere else that not only is painful but in the case of Edema you would have a lot of extracellular fluid what does that do to the rate at which those cells can get oxygen and glucose in the blood the rate at which those cells can get oxygen and glucose decreases that rate because you've just increased the distance the diffusional distance from blood to cells just increased so getting those cells what they need difficult so those cells aren't going to do so good so we have to be able to manage the extracellular fluid blood's an easy one to understand extracellular fluid people forget about because it doesn't get sort of the same level of well that's not too sexy I'm not going to talk about composition of blood I'm going to talk about composition of ECF that is equally important moving on let's talk about regulated versus unregulated or nonregulated physiological variables not everything in the human body is considered managed as part of homeostasis some things are allowed to vary widely and some things really aren't allowed to vary at all I even put a chart in your eex about examples of regulated physiological variables when you look at something like that should you memorize it no charts are for reference but what you should do is start to draw patterns about what do these things have in common what are some Trends we can notice and you'll find that those Trends are things about the blood and ECF those Trends are also called regulated physiological variables let's talk about what is a regulated variable versus a non-regulated variable so I'm going to come over here and talk about the regulated ones first regulated physiological variables are the ones we have to manage because they're critical for survival they have to be really carefully controlled there's not a lot of wiggle room for some variables there's hardly any wiggle room and then I'm going to talk about what do we need in order for a variable to be considered regulated turns out there's not as many as you might think but they're really important I'm going to give you an often overlooked but super critical physiological variable highly regulated not a lot of wiggle worm if you work in an ER you'll know how important this is if you're going to any sort of health professional school after this you're going to spend a lot of time talking about this variable and that's pH what is the acceptable range of pH in the blood 7.35 to about 7.45 good job whoever rattled that off good job that's not a lot of wiggle room so are we neutral no we're a little bit basic ideally this is a really tightly regulated physiological variable blood PH does not get to move much at all what do you think could impact blood pH these are also regulated physiological variables what can impact blood pH why do people end up in such blood pH problems in the emergency room CO2 CO2 good job CO2 is really the number one thing that impacts blood pH so blood pH is really a factor of things like blood CO2 and so automatically we've just made the jump from conceptual homeostasis to blood to physiology to survival to ER stuff so if you're going into any sort of medicine at all nursing school hits this really hard you're going be talking about blood pH so it turns out blood pH tightly regulated and it has a lot to do with blood CO2 because CO2 plus H2O nice trip back to chemistry plasma is mostly water when CO2 disol dissolves in H2O what do we get what's the compound it's unstable does stick around but it's there H2O CO2 you're so close good job because you didn't know I was going to ask this today so good job H2 CO3 highly unstable it dissociates into some things that are going to cause US problems one of those is that and then we finish that off with this what happens when we have a lot of protons being donated to a fluid what happens with a pH starts to go down and if we overwhelm this amount compared the buffer really get into trouble we can overwhelm that easily because this is not the only thing creating acid we're going to create a lot of acid but we don't buffer it so well blood pH starts to drop we enter something called acidosis could be metabolic acidosis could be respiratory acidosis to that patient it doesn't matter exactly they're just in trouble and so as the clinician you're going to have to figure out how do you manage that how do you fix it before it becomes fatal and this is such a pervasive problem for lots of different reasons why people end up in the ER heart problems respiratory problems tumor Mass lymphoma that all end here kidney failure all here so it turns out at the end of this why I'm making such a big deal out of blood pH is because regulated physiological variables are super important for survival and we we can see that quickly when they start to fall apart Things Fall Apart quickly so regulated physiological variables what does it take to be a regulated physiological variables of all the variables in the body what do we have to have to make one considered a regulated physiological variable there are three things and if a variable does not have these three things it's not regulated it's a non-regulated variable there's a lot of those too three things one we have to have a dedicated sensor in physiology those are called neurons Sensory neurons with receptors and sensory neurons are able to detect a very specific variable a specific stimulus and if they they detect something that triggers them they will send a signal and that signal goes to the second thing that's required for homeostasis and that's a dedicated control center in physiology that's usually the brain specifically the hypothalamus not always but usually and then the third thing we have to have for our regulated physiological variables are effors and effors are anatomical structures that can do something these are things we could dissect in a cadav and say there's one there's another one and here's a whole bunch of them defectors are structures anatomical structures that are charged with fixing the variable back to this this is our problem blood pH is starting to tick down 7.3 7.25 all sort of problems going off the control center says well I got a problem what factors might you think would be involved in fixing this what defectors would be employed some buffers buffers maybe some buffers give me an anatomical structure though keep it in the realm of an anatomical structure what would cause carbon dioxide to creep up anyway problem in the lungs so what might we use to fix it the lungs we might just increase respiratory rate let's get rid of this carbon dioxide we're going to blow off this carbon dioxide that's going to help in the short term and the long-term kidneys are going to have to manage all this too short-term lungs long-term kidneys so that's some effectors these are actual organs we can look at go uh oh we got a problem what's going to be involved in fixing it lungs what happens if the person has COPD and pneumonia and their lung function is compromised then you got another problem to manage which is you have continuously increasing protons you got a pH problem and the main Defector that's charged with getting rid of it is taken offline you're going have to figure out how to fix that and that's complicated from a scientist is interesting right so we can kind of look at this in two different ways so that's how people can get in trouble quickly when their regulated variables are off sometimes it's the effector that can't get the job done let's talk about non-regulated variables these are important variables I'm not saying they're not important just because they're non-regulated doesn't mean we just ignore them these are important we can measure them you can even wear the variables like eyewatch apple eyewatch or Garmin they measure all these doesn't really contribute to homeostasis but they're still kind of important so nonregulated variables are important they're measurable but they're not controlled there's nothing that prevents them from going really high or becoming a lot lower lower they are allowed to fluctuate or swing widely they need to and that's because those fluctuations are actually really helpful for managing our regulated physiological variables I'll give you some examples and that might make it a little more concrete examples of important measurable but not controlled variables includ heart rate heart rate is not controlled nor should it be if you had to keep your heart rate in a narrow range let's say 72 beats per minute what would happen if you had to get up and run really quickly away from danger could you nope you'd be like uh oh this is bad or if you went to sleep your heart would still be racing also bad so heart rate is not a regulated physiological variable another example respiratory rate and that might make my other example down here more meaningful respiratory rate can swing widely why do we need it to swing widely what are we managing in a way by allowing respiratory rate to swing widely blood CO2 levels you got too much CO2 increase that respiratory rate get rid of that carbon dioxide so some things need to fluctuates some things cannot I'll pick it up here on Thursday have a good mid part of your week