many students ask me on the first day of anatomy class where do I even begin there's like a million terms in my textbook and I don't know how everything connects and there's just too much to study I always give them this answer watch this video first hey everybody organized biology here where we make difficult biology Concepts simple and today we going to dive through an overview of all of anatomy and physiology this is going to give you awesome value whether you're a current Healthcare professional you want to refresh on anatomy and physiology topics or this is the very first time you've even taken an anatomy course I'm going to walk you through step by step by step the most important ideas of& as well as giving you helpful tips on how to connect Concepts and how to understand the whole entire class in a very simple way be sure to watch this in order all the way to the end so you don't miss out on anything so where do we begin well first we need a box okay so here's your human anatomy and physiology box your box may be more empty or more full than others okay so I want you to imagine this box inside of your brain and what this box is called is actually a schema don't get lost quite yet this is actually just a learning theory okay so you have these boxes called schemas these big ideas of things and your goal in learning any topic is to basically take a bunch of information and actually do what's called assimilation so we're basically placing ideas inside the big box that is anatomy and physiology so let me give you a few examples of what we could assimilate all right so in your anatomy class you're going to probably talk about the blood talk about pH the kidneys and this big weird term called the homeostasis which is probably the most important idea in anatomy and physi ology but here's the thing you're going to be taught them in a vacuum your teachers are likely going to say hey just like take this box of pH and throw it in right and then take the box about the kidneys and throw it in you'll be taught in this very isolated manner right but here's the thing your body is amazingly complex and intricate everything connects to everything so for example check this out homeostasis is basically keeping your internal environment constant and there are some things in the blood that you have to keep constant things like blood pressure things like fluid amount and also things like pH so not only are you assimilating these ideas individually but you can also connect them but then you can take it a step further and say well these are things we have to keep constant in order to stay alive the organ of the kidneys actually helps to maintain these values so not only do you want to assimilate each individual piece of information you also want to draw connections or think of these as little strings or wires connecting the ideas before you actually place them into your big box of anatomy and physiology so throughout this whole video and throughout your class I want you to try to draw as many parallels as possible because that's going to increase your learning the big first question let's get it out of the way what the heck is anatomy and physiology so Anatomy first what does that mean well Anatomy just refers to the structures of the human body so Anatomy always answers the question what does it look like as well as what is it made of so one of the ways I demonstrate this in class is I pick up a random object like this pillow and I basically ask what is the anatomy of this pillow and most of the time people will say well it is white right so what does it look like it's white it's got some blue lines on it it's got these little weird tassels that kind of confuse me and it's also soft right so these are all the structures of this pillow but that's not the whole story right you see we know the structures of the pillow it's pretty obvious kindergarten student could have answered that but then the question is what does this pillow do well obviously if you're going to bed you use a pillow to obviously cushion your head as you sleep you could use it as a throw pillow which I never fully understood why it was called a throw pillow maybe it could serve as some back support right so that as I teach I can just feel relaxed but now I can't really write on the board so I'm going to get rid of this throw pillow all of that to say was all the things that the pillow does or its functions right and that's going to be the physiology so what question are we answering here well we're answering the question what does it do now these are not separate ideas they're one and the same because the structures of the body will determine the functions of the body so I always say that structure determines function so let's take an example inside the human body on relating the structure to the function in a cell called a neuron so here's a tip whenever you are starting to learn about a certain subject like a neuron I want you to ask the question first what is the neuron's anatomy remember because if you can determine its Anatomy you can probably determine its physiology as well so looking at this neuron well what do we have here we have these little antennas in a way called dendrites I say antennas because they kind of look like these little Branch structures right so that's the structure in some neurons this one specifically has this long end that is covered in in insulation and this insulation is called myin so we're insulating this long part of the neuron that can actually be up to about 3T long which is absolutely crazy so based on what you see right you see these antenna in a way you got this long part called the axon that's covered in insulation what do you think this neuron does well based on what it looks like if this is an antenna we know that antennas receive information so we could say the dendrites the anatomy is kind of branched and the physiology the functions of the dendrites would be to receive information whereas the axon is this long insulated process right just like you see probably in different types of wiring right you see the wire but you see the insulation on the outside of the wire and what the wires do the insulated wires do is they help send signals so this axon this lung part exists to send signals so you now know the anatomy right what it looks like and you also know the physiology of the neuron to receive signals and send signals awesome and you can do this for literally any organ cell structure of the body from the mouth all the way down to the anus okay let's not talk about the digestive system yet all right great but why do we have these neurons why do we have kidneys why do we have blood what's the what's the pH why do we have to have our acidity levels right well all of anatomy and physiology ties into one single concept and that is going to be homeostasis so let's talk about that next now to understand homeostasis I first need to tell you the most pessimistic view of the human body and that is that everything outside of you literally exists to kill you now if you don't believe me let me just give you a short little list okay so fun fact the air temperature is 70° fhe well you know that your body temperature needs to say probably around 98 degrees fenhe right furthermore there are probably trillions of bacteria crawling specifically on your phone right now maybe on your mouse your computer and if they were to hop into your bloodstream they would likely murder you and furthermore the air outside likes to evaporate water if you haven't realized this before if you spill some water you come back the next day it's gone it all evaporated right well your body is made of 65% water and the air could quite literally evaporate you very quickly now there's other things that could exist to kill you outside but this is just a short list so notice these types of things right keeping your body temperature at the right range keeping your body around 65% water preventing bacteria and viruses from getting inside of you all of these things tie into the idea of homeostasis now what is homeostasis it's the ability of your body to maintain an internal set of specific condition conditions Okay so we've got all these things inside of your body you have to keep within this certain set right and you have to be able to maintain it so for example with body temperature I gave you a specific range of 97 to 99 degrees Fahrenheits so this is considered the homeostatic set range so your body is going to continually doing everything it possibly can to keep your body temperature in this range right this is because this specific body temperature helps maintain life and that's what we all want right is to sustain life now there are so many other homeostatic set ranges like blood pressure blood pH electrolyte levels oxygen Etc and there's so many other set ranges of different things like this but key point if you are unable to maintain homeostasis of any of these ranges it is called disease you've obviously heard of diseases before and a disease by definition is the inability of your body to maintain homeostasis so for example if you've been smoking your whole life and you have like a disease called COPD right chronic obstructive pulmonary disease your blood oxygen levels will likely not be in the set range and if they're not in the set range and you can't keep it in the set range that means you have a disease and ultimately if diseases are not fixed it usually leads to obvious death because remember homeostasis helps to maintain life so the opposite of Life obviously is death so what a beautiful way to look at the world every outside of it exists to kill you and if you can't keep homeostasis you end up dying but that's logical right but I didn't tell you the full truth you see not everything outside of you exists to kill you so this statement is basically false because there are some things outside of your immediate bodily environment that are essential for you to live and these are other things like nutrients and oxygen from the air and water and so forth and so on so when in doubt always come back to the idea of homeostasis keeping your body within a set range of specific internal conditions but maintaining homeostasis is an incredibly complex process you've got all these different values so therefore you have all these different structures of the body that are going to function to help maintain homeostasis but in order to understand that we have to use a very good analogy to help align something we know with something we don't necessarily know too well in the human body okay so here's the next question how do we understand how the body is organized or structured right to help maintain homeostasis well let's relate this question to the idea of a business so what's the goal of any major business like Amazon or apple Etc well the business wants to create an ideal environment but not just for good workers conditions although they should fight for that but specifically why do you have a business it's to make a profit and you can contrast with the human body's goal right you can say that the human body's goal is to create an ideal internal environment to help what well help to maintain life as we previously learned so both a business and the human body are one and the same we need to make a good environment and we need to either make a profit or maintain life so let's roll through first how the business is organized to help do this so first you have the idea of a business think in a big scale right like apple well then Apple has specific Office Buildings and within those Office Buildings you are going to have a lot of different offices right and obviously within those offices you have these clusters of workers right like janitors like software Engineers it's Etc and usually these people work together right but then finally the smallest unit per se of a business would be the individual workers so in order to build a successful business you essentially have to work from the bottom up you have to understand what the individual workers are doing as well as the groups offices and the whole scale buildings themselves in order to run an efficient business to make a profit well what's amazing about this analogy is we can perfectly compare it to to the human body so well what do we have in terms of organization for the human body well obviously in the big scale it'll just be the human body itself and we're considered an organism well what is the body primarily made of in its next subdivision well we know that the organism is a combination of a bunch of organ systems organ systems things like the cardiovascular system so just like the Office Buildings the systems have a very specific role within the business or within the human body now the organ systems then are built from Individual organs organs like the heart and blood vessels so just like the organ systems are composed of organs so too the office buildings are built from the offices really cool now although the organs are individual units by themselves they're made of different things just like the offices they are made of groups of cells called tissues so for example you have the groups of workers like the janitors well a group of similarly functioning cells would be something like the measy which actually stands for muscle cells within the heart or also some of the blood vessels so we have groups of workers on both sides but then what's the individual unit of the human body well the functional unit of any organism is going to be the cell so an individual myosite would be a cell but here's where the human body is a little more complex than a business per se is because the cells are further subdivided into small and smaller parts so the cells are made of organel which are made from macromolecules organel meaning quite literally a tiny organ within the cell macromolecule meaning big molecules followed up by molecules and finally atoms so this is not to scare you I'm going to go through some of these things here in a little bit so here's the thing in order for a business to function properly all of the individuals workers need to know what to do when to do it how much how little right in order to function properly for the business to make a profit all the same way these cells right the main workers need to know how to function when to do their things and so forth in order to help the human body sustain life so anytime you see a cell or a tissue or something along these lines doing something it's because it's helping the human body as a whole maintain homeostasis but the next question I want to address is how does an individual worker know what to do within the business in other words how does a cell know what to do within the human body because you are made of quite literally 30 trillion cells that would be a really big business if you had 30 trillion workers right so if you have 30 trillion cells and they all need to do a specific thing at the right time how do they know what to do let's get into that next all right so here's when things start to get a little more interesting and really applicable to the subject you'll learn in anatomy and physiology first off how do our cells know what to do and when to do it this is really complex because cells exist individually right but you have 30 trillion cells within your human body so all of them need to know basically when to do things and when especially not to do things right so first first I'm going to talk about how individual cells know what to do by themselves so inside any cell you will have a structure you've probably heard of before and that's called the nucleus and most cells have a nucleus exceptions would be like red blood cells but the nucleus contains a very very important Macro Molecule we call a nucleic acid now specifically this is going to be DNA which stands for deoxy ribonucleic acid really big word sounds cool makes you sound smart but DNA I just want you to think of this as basically a big recipe book for the cell now just like recipe book you and I have at home maybe I mostly have just dessert recipe books uh but these recipe books will contain a lot of different recipes now what do recipes make obviously for us they make food but for the cells they produce proteins now proteins are another Macro Molecule just like DNA but they're very very very specific in structure and so we can conclude that whatever proteins a cell makes that cell will have a specific structure and therefore a specific function anatomy and physiology right so what any cell will do is basically read certain instructions inside the DNA those instructions will be copied onto a little transcript called mRNA eventually going to these little chefs called ribosomes and these ribosomes will take those instructions in the MRNA and build the protein and when you need to learn the specifics about that process I recommend you watch this video here on protein synthesis it'll go through the details of this but just for now know that cells build proteins and that gives them their structure function but here's the thing I'm going to talk about here in a second cells inside of your pancreas little organ tucked underneath your stomach and then I'm going to talk about your biceps or your skeletal muscles right obviously this is not the same as that but what's interesting is inside the cells they have the exact same DNA for the most part besides your sex cells like your testes and your ovaries they'll make a little different cells of different DNA that that's for a later video so if all of these cells like the pancreas cells and the bicep cells have the same DNA why are they making different proteins right because the proteins are the structure and function of the cells well although they have the same DNA they read different parts and these different parts or segments of the DNA that make proteins are called genes so that's where we get the terms gene expression right these cells expressing specific genes that are encoding specific proteins that build their specific structures great so that's a real brief overview on Cell Biology which you can learn more about in this playlist after you get done with this video but now I want to bring back the idea of how do our cells know what to do and when to do it so we're going to key in on two organ systems these are kind of Big overarching Ideas like the Office Buildings right we're going to talk about the nervous system and the endocrine system so these systems exist to essentially tell the cells what to do and when to do it so let's tie this all together let's say for example you want to contract your bicep well the cell will have previously built itself to be prepared to contract what do I mean by that well if you look at these cells these are called muscle fibers otherwise known as muscle cells and what these cells have done is they've read their DNA from their multiple nuclei within cells which is interesting these have multiple nucleuses inside of each individual cell super cool and the reason for that is because they build a lot of proteins okay so the proteins these guys produce are proteins called mein literally translating to muscle protein actin literally translating to the aced upon protein and then Titan literally translating to very large protein as you can see all of these proteins end in i in just like the name protein itself which is really cool now all of these proteins as well as others will quite literally build the skeletal muscle so that we'll have all these striations so you see these up and down Stripes what those guys will do is accordion together so all of these lines will accordion together to contract which is super cool because if all those little accordion lines come together the whole muscle contracts and you move your bicep you want to learn more about that sliding filament theory but let's stick stay here and talk about how these cells know what to do okay they built themselves so they can contract right when do your muscle cells know to contract when do I know how to do this well it's when you want it to right you contract your muscles when you want it to but what told the muscle cells to contract in this case it was the nervous system so your nervous system consists of your brain and your spinal cord in your brain spinal cord are called the nervous system because they're made of those neurons remember these guys which we drew earlier they basically exist to send and receive signals so what will happen is when you want to move your muscle just as an overview there will be a neuron from your brain that will extend down through your spinal cord exit at some level and then come and directly communicate with your skeletal muscles so what they're going to do is they're going to produce a little chemical called a neurotransmitter which is basically a chemical signal and that signal will tell the muscle cells to contract but wait there's a problem because anytime you have a signal that is being sent you need something else in order for that signal to do its job you need a receptor right so in order for this signal to be received by the muscle cells to actually contract well we need to have a receptor based on what you've learned so far what do you think the receptor will be made of well in order to build the structures of the cells you need those proteins right so the receptor will actually be a protein on the skeletal muscle cell that is structured perfectly to fit those neurotransmitters then as those neurotransmitters bind to the receptor the muscle cell gets excited and it will contract so this is a great example of how the nervous system right can communicate directly with cells via those chemical signals as long as they have the receptor to change their function so they know when to do it now the fascinating thing about this is that you consciously can control your skeletal muscles because it originates in a brain region that actually is controlled by your conscious thinking so that's just one example of how the nervous system can communicate with cells to change their function and there's a lot more complexity within that if you want to learn about it but then we also have a system called the endocrine system now the endocrine system is composed of a variety of dis different organs like the pancreas that we'll talk about like the thyroid gland like the pituitary gland in your brain they're going to direct when cells do specific functions now in this case the endocrine system is going to deal with chemicals in the blood now the reason the endocrine system uses the blood to send signals to different cells is because the blood goes to virtually every cell of your body and we'll talk more about the blood importance in The Next Step so if the blood goes basically everywhere that includes all the pancreas cells which I've drawn below now this specific cell inside of the pancreas is called a beta cell and the beta cell is going to produce a protein by reading one of the segments of its DNA and that protein is going to be called insulin quick quiz how did I know that insulin was a protein well because it ends in that I in right so insulin is going to be a type of hormone which is basically a chemical messenger or signal in the blood that's going to change some sort of cell functioning we'll get to that here in a second now what this hormone will do is actually lower your blood glucose levels otherwise known as your blood sugar levels all right so blood glucose well glucose is sugar right so in your bloodstream at any moment you'll have a certain amount of glucose in your blood and just like we talked about earlier glucose has a specific set range in terms of homeostasis in your body and that set range is anywhere from 70 to 100 milles per deciliter that's not a unit you need to memorize by any means I just mean there's a range right so let's say for example right now your blood glucose is at 140 milles per DEC well that obviously is outside of the homeo itic range so what would cause this well if you ate a really sugary food like candy bar your blood sugar will likely Spike because all that Sugar dumped into your bloodstream we know that that is bad so we need to bring it down how do we do it we need to do it with that hormone insulin because it'll lower our blood sugar levels but here's the thing in this case the blood glucose is almost acting as the signal right that's some sort of stimulus that is out of homeostasis so in order for the beta cell to even realize that glucose is too high it needs to produce produce again a receptor protein and this receptor protein that made from Reading specific segment of DNA is going to detect blood sugar levels and obviously as soon as it detects this high blood sugar level it's going to induce a cellular response that will kick insulin into the bloodstream and eventually insulin will do an action on a variety of different cell types including the muscles interestingly enough and it will lower that blood sugar back to homeostasis will say around 90 so two systems of the body the nervous system and the endocrine system will basically tell these cells directly through neurotransmitters or actually through hormones to go and act on other cells and tell them what to do and when but wait I have another question that's kind of bothering me how did these cells actually have the bricks per se to build themselves how did this cell build itself with no materials how did this cell build itself with no materials think of these cells as Just Like Houses they didn't just build themselves they needed raw materials in order to build it so the question that's coming up next is how do your cells get what they need so now we're going to answer the question how do our cells actually get what they need and if this has been helpful so far this entire video series please consider liking this video subscribing to the channel I'll continue to make all these complex ideas more simple at organized biology so first we need to start with the cell itself so this is going to be any cell and notice I've drawn a lot of cool little STP structures inside of the cell so the cell as you can see is made of a cell membrane which we can see is what's called a fat or a lipid right so this is made of a fat then we've got a lot of these different proteins right the cell has built and it's in its membrane there will also be different proteins basically inside of the cell too within the nucleus membrane as well we'll also have some carbohydrates that will act as little ID tags on the cell and we'll talk about the need for them in terms of energy production here in a second and then finally also have our nucleic acids in the nucleus right and then water so the cell is built of a lot of things and it needs a lot of things to continue functioning properly so I'm going to split the cell's jobs in a way in terms of number one building itself as we mentioned previously as well as we need the ability to produce energy within the cell and energy in terms of the cell is going to be through a molecule called ATP now I made a couple videos on ATP if you're confused about it so hop over there if you need to but ATP is basically the energy currency molecule for the cell so just at like an arcade you need to use those little tokens you need to basically convert any sort of money out here into those tokens so that the game can work properly we have to convert energy from the outside environment that will actually eat and we need to convert it into this molecule so how do we do that well we need to go through a process called cellular respiration and the best kind of cellular respiration in terms of your textbooks will be when we take a carbohydrate called glucose and we basically burst the glucose apart with a very very important molecule called oxygen which is a gas O2 and what will happen is we're going to do some chemical reactions with that and produce our happy molecule ATP but we'll also make two other byproducts one interestingly being water as well as carbon dioxide so this is the classic cellular respiration equation where we're basically taking carbohydrate and oxygen blowing it up Mak a lot of ATP and then producing a couple byproducts so that's happening within this cell so if this cell is constantly doing this we know that we will have relatively low glucose inside of the cell as well as low oxygen so in order to continue producing that ATP molecule we need to bring glucose and oxygen back into the cell to replenish it and furthermore in order to build all the structures and maintain the structures in the cell we need to basically bring in a bunch of fats proteins nucleic acids and other carbohydrates in order to keep the cell built so how do we keep this cell Happy by building itself and making ATP a few different systems number one we're going to use the cardiovascular system now the cardiovascular system quite literally means the heart and the blood vessels and as I mentioned previously the vessels go virtually everywhere so we can basically talk to each cell of the body via the blood so what the heart is going to do is it's going to continually circulate circulate the blood so Whatever Gets In The Blood it's going to be forced in a oneway direction constantly so let's start first with the respiratory system so the respiratory system I drew in this kind of purple I think this is purple I'm color blind so please make fun of me in the comments if I'm wrong but this respiratory system exists to bring air into the lungs and then expel it now specifically inside the lungs the air is going to be very high in oxygen and that's the key so when the heart pumps out on its right side it's going to go to the lungs and the oxygen is going to flow into the bloodstream and from there if you trace the oxygen it will get into the left side of the heart get pumped out and then actually go down to the cells so the cells being low in oxygen will get bathed in a high oxygen environment from the bloodstream which is going everywhere and the oxygen is going to flow from high to low very common core concept and oxygen is going to get into the cell so we can feed it for cell respiration wonderful but remember we also need sugar or carbohydrates as well as all the other structures of the cell to build it well oxygen was delivered by the basically the respiratory system cardiovascular system but as the blood continues to circulate throughout the body it also bypasses the digestive system and when you eat anything you are quite literally eating living things you are eating the cells of other plants and other animals so in essence every single molecule that you build your cells in you are going to put through the digestive system break them down and from there all of these nutrients including water will pass into your bloodstream and if you follow the path all the way back to the heart to the lungs and then back to the cells we are now able to feed the cells the nutrients that they need now notice when the nutrients come in they're pretty big molecules so let's say we've got glucose in this green circle the glucose will have to pass through a protein channel it's a really common concept that we'll see in order to get big things into the cell we have to use these little protein channels now other like fats and oxygen can just pass right through and if you want to learn more about that process go ahead and hop over to cell transport but overall how does this cell get its building blocks get the oxygen the glucose and all that stuff from the respiratory system with the oxygen and then the nutrients coming through the digestive system into the bloodstream getting pumped by the heart back and then back to the cells awesome but here's another problem I mentioned when this cell is doing that respiration right I boxed off CO2 because CO2 is going to start building up inside of the cells and CO2 inside the cells can actually be toxic and so the cell being high inside with CO2 is actually going to dump that CO2 into the bloodstream and the problem with CO2 is just like carbonated beverages it can make your bud your bud your blood bubbly so we in the bloodstream actually convert that CO2 into something called carbonic acid and acid can really ruin your blood pH and as we saw in the beginning of the video blood pH or the acidity level of your blood is a homeostatic variable if it gets off you could risk killing off all of your cells so we understand how the cells get what they need but now how do we keep the blood bathing them in the proper environment so how do we keep this Blood basically free of toxins free of too much acid free of too many dangerous metabolites or that you may have eaten that aren't good how do we get those bad things out and how do we keep the good things in so let's address that next all right on to the next see I hopped in from this side this time I got to keep you on your toes all right so next question how do we keep ourselves bathed in the right environment in other words how do we keep the blood contents and amount within a proper homeostatic range in order to help bathe our cells properly so they get what they need and they don't get bathed in the bad stuff so here are some blood values we're going be maintaining and I'm going to kind of correlate these as we go through different systems of the body like the urinary system respiratory system Etc so all this goes back to that key point of homeostasis so first off we're going to talk about the lungs and we already talked about how the lungs are going to bring in air when we breathe in and it's going to have a lot of oxygen in it and that oxygen since it's in high concentrations in the lungs it's going to want to flow into the bloodstream so that is how we maintain our blood oxygen saturation simply from the respiratory system right now with oxygen Oxygen's obviously going to go travel to the cell cell is going to make that ATP we just talked about and that's great but remember those cells also produce that byproduct of CO2 so these cells are pumping out that CO2 from high to low from the cell into the bloodstream and we know that that carbon dioxide makes the blood acidic so with that carbon dioxide we need a way to basically get it out of the body so it doesn't make our blood too acidic or bubbly as we talked about so when the CO2 get to the lungs inside the lungs there's a relatively low amount of CO2 because of the air outside of us is very low in CO2 so that CO2 will flow from high concentration to low into the lungs and then the lungs will compress and push that CO2 out and that will actually help make our blood slightly alkaline which alkaline is basically the opposite of acidic but what is acidity anyway well I go through it in more detail up in this video here talking about basically acids and B the basics but what acidity is is basically hydrogen ion amount so the more hydrogen ions the more acidic the solution will be okay so how does co2 that has no h in it make basically the blood more acidic and have more hydrogen ions well CO2 will rapidly combine with water in the bloodstream and actually be converted into hydrogen ions and bicarbonate ions so since we increase that hydrogen ion amount in the blood from having a lot of CO2 forces the reaction to make those hydrogen ions so in essence the lungs can kind of play with the hydrogen ion amount by playing with how much CO2 is exiting the lungs so the respiratory system in the lungs really help to regulate our blood pH awesome now let's talk a little bit more about these hydrogen ions and potentially other electrolytes inside of the bloodstream for example we'll have ions like calcium sodium and potassium in the bloodstream in certain concentrations right now these are charged atoms so they're actually called electrolytes because charge means they have some sort of potential of electricity kind of cool right and you've heard of them in your Gatorades before right Gatorade has some sodium maybe some pottassium in it great so your blood concentration of these electrolytes has to stay constant very important now if you were to not drink any water or not drink or eat anything with these things in it you still have to keep the electrolyte levels constant in your blood so what is keeping those electrolytes constant in your blood the kidneys the kidneys I like to think is basically the greatest garage organizers in the world now what do I mean by that that has nothing to do with electrolytes unless you store a lot of Gatorade in your garage uh well when you're cleaning out your garage what you have to do is take everything out first right so what the kidneys do first is they take all these things out of the blood essentially filtering them and they will decide hey what needs to stay in the blood and What needs to go out of the blood anything that needs to stay in the blood the kidneys will actually be able to reabsorb back into the bloodstream so what types of things will the kidneys reabsorb well the kidneys will reabsorb good things so things like glucose and amino acids the base unit for proteins as well as anything like electrolytes that are getting too low so let's say for some reason you have low sodium in your blood right and you're not eating any salt so you're not replenishing it that way through the digestive system what the kidneys will do is decide hey we have low sodium in the blood and we need to keep it up right so the kidneys will begin throwing back those sodium ions back into the bloodstream but wait the kidneys can also decide hey what if something is bad or what if something is in excess well in that case what the kidneys can do is throw the excess or the bad stuff into urine so let's say for example you just drank a gallon of water in 5 minutes because you're stupid and you want to I don't know do some sort of challenge that your friends wanted you to do from Tik Tok never a good idea and so all of a sudden in your blood you've got just a ton of water well if you have way too much water in your bloodstream what could happen is your blood volume your blood pressure would get increased you could pop some blood vessels bad things could happen very quickly so what your kidneys will do is it'll detect all of this water and decide whoa there's way too much here we need to excrete it out as urine so obviously your urinary bladder right here will fill up fill up and you will have to pee a lot because that is what happens when the kidneys filter out excess stuff as well as bad things things like Ura for example and last but not least the kidneys can also decide how much hydrogen ions to reabsorb as well as what we call Buffer now I'm not going to go to the details of this but buffer almost acts like a little molecular Swiffer that will help sweep up those hydrogen ions to prevent the blood from getting too acidic okay so think of the buffer as like a Swiffer Duster and the hydrogen ion like the dust right so let's say there's way too much uh we'll say hydrogen ions so the blood is really acidic so there's a lot of hydrogen ions in the blood what will the kidneys want to do well there's too much right so what will we want to do we'll want to excrete it out as urine but the kidneys go one step further and say well I'm going to excrete out some hydrogen ions but if it's really bad what I can actually reabsorb is more buffer things like bicarbonate which you can learn about in my other videos here but in essence the kidneys are just adjusting adjusting adjusting constantly based on what's In The Blood so that we can keep these values constant so as you have noticed the kidneys are able to number one regulate your blood volume and pressure also through a process called the renin Angiotensin aldosterone system you can learn about there we can also regulate PH that hydrogen amount with the kidneys and you can also help regulate electrolyte levels in the blood and you can argue that things like Ura and other toxins can be excreted out of the the blood so the kidneys will excrete those out into urine as well nice okay so now we're back to the heart and clearly I have not mentioned two other things that are on my board we've got the lymphatic system and we've got the liver which is just an organ not a system like these guys are so let's talk about the liver first the liver will contain if I had my green much better the liver will contain a lot of neutralizing enzymes and enzymes are basically proteins that the liver cells the hepat ites are producing constantly and these are proteins so these enzymes act as little scissors or staplers for chemical reactions and these enzymes will help neutralize different toxins the enzyme that helps neutralize alcohol is actually called alcohol dehydrogenase big scary word but no if it ends in Ace you know that it is an enzyme basically doing a chemical reaction to neutralize the alcohol now regrettably that makes a intermediate called acet alide which is basically kind of cancer causing which is not good so that's why excess alcohol ingestion is a really bad thing and actually can ruin your liver from that through curosis so that's just one thing the liver does is that it frees up the blood from those toxins but it'll also help to package carbohydrates adjust lipids alter protein synthesis all sorts of things the liver is an amazing organ last but not least we've got the lymphatic system let me erase this here now the lymphatic system is a separate circulatory system so know that the bloodstream is the cardiovascular system otherwise known as a circulatory system because we're circulating blood throughout your body and there's actually 60,000 miles of it which is crazy but at the level of the cells which is really tiny we're actually going to feed the cells by losing some fluid in the blood out through these little holes of the blood vessels this is called capillary exchange and as the fluid gets out some of the nutrients like glucose will actually go into the cells and help to feed the cell but that being said you are losing some fluid from the blood right so if you lose fluid from the blood you will lose blood volume right so if that kept happening you would all of a sudden have no blood left you just lose it all as fluid and that's a bad thing so what happens is is most of the fluid re is reclaimed back into the blood about 90% of that fluid through a process called osmotic pressure but then 10% gets stuck just stays there actually not this is where the lymphatic system comes in and what the lymphatic system does is it reclaims that temper in of fluid that will now call lymph all right so why are we doing this well as you can see the lymph is eventually going to make its way back into circulation it'll actually dump back in in your subclavian vein right under your clavicle but what's interesting is inside lymphatic system these vessels we will have very very important cells and these cells are going to be called lymphocytes and lymphocytic system cell and what the lymphocytes do is they help mount an immune response if there are bacteria or viruses or any other pathogens right disease causing things inside of that fluid so think about it if there were some bacteria that somehow got into your blood that bacteria might leak out and get into the lymphatic system before it gets reintroduced back into the bloodstream where it could go everywhere and just kill you very quickly instead we reroute the bacteria through basically this Gauntlet of a lymphocytes that are made to identify and then destroy these bacteria or viruses or what have you after going through the buzz saw that are your lymphocytes and this is actually a structure called your lymph node there will likely be very very little bacteria that will actually get reintroduced back into your bloodstream and that's how you help fight off infections is through this lymphatic system so therefore the lymphatic system helps keep your body free from those pathogens so all in all you see how multiple different systems as well as an organ by itself is helping to maintain these values of blood homeostasis so therefore our cells are bathed in the right environment but let me tell you one thing these lymphatic vessels are just not enough to protect ourselves from everything that might want to kill us in this world so we need a few extra um helpers to help prevent us from getting infected or mauled by a bear nah okay your nervous system likely detected that frightening face but I also came up really close to you so your nervous system detected that right you sensed it and then you probably jumped a little bit right so you were trying to protect yourself specifically with some muscles to either fight me or run away from me so next we got to talk about how we protect ourselves so let's first talk about how we externally protect ourselves I'm going to start with the skin because that's the major covering of our body that prevents bad things from getting in so if you were to take a cross-section of your skin so if you like take your skin up and kind of cut it in half and look inside the skin you would see three distinct layers you'd see the epidermis which means upon the skin you'd see the dermis which just means the main tissue of the skin and then the subcutaneous or hypodermis not considered a part of the skin but it's still there now all of your other underlying structures like your organs your muscles your bones Etc are underneath the skin so why do we have it well let's say that there are those bacteria outside and viruses floating around and they like to look for a warm home that has plenty of nutrition otherwise know as the inside of your body right specifically your bloodstream so these pathogens want to get into your bloodstream but they can't because the bloodstream is protected by the epidermis which is basically a bunch of flattened cells of your skin that are constantly shedding constantly shedding basically protecting you from the outside environment so the skin helps protect from anything out here like pathogens as well as temperature changes because remember the inside of your body is about 97 to 99 degrees Fahrenheit and you want to keep that constant so if it's too cold what the skin will do is kind of insulate you right as well as help alter the blood vessels to help you stay warm or cool depending on what the environment is outside talk a lot more about that in the integumentary system video but I also want to key in right here on this hair follicle you see at the very bottom of this hair follicule you've got a lot of these little Sensory neurons and these Sensory neurons can actually send a signal back eventually to the brain if this hair follicle stimulated so let's say for example you've got a black widow spider crawling on your arm now don't they have that big like weird looking like thing on them like that we'll go with that so there's a black widow spider the thing about the Black Widow is it's really really lightweight so you cannot detect it if it's just walking on that epidermis but if that spider were to tap your hair follicle these Sensory neurons will send the signal back to the brain and you can reflexively look at that spider and hopefully use your muscles to H it off before you get bitten right so that's one way we protect ourselves we're able to detect things outside of our environment as well as prevent certain things from getting in regulate our body temperature keep our water inside Etc so there's a lot of things the integumentary system does that doesn't have to do with protection but is a really main protector we also have the skeletal system so your bones and then your skeletal muscles like your biceps your quadriceps Etc now obviously those are used for movement and that's a good thing because a lot of the times we need to either run away from dangerous things or fight dangerous things talking about you know the Neanderthals way back in the day right so in order to protect ourselves from any other bear or mountain lion we have to be able to move so that's why I'm grouping it here but more specifically if we want to protect the most important parts of our body like our brain like our heart like our lungs that help keep us quite literally alive we need to protect them with very strong bones right so you know your heart and your lungs are inside your thoracic cavity that's fully protected by your rib cage very very good structure to protect yourself furthermore your brain is helped to be protected by your skull bones and your spinal cord that runs down the length down to your sacrum is actually protected by those vertebrae that help keep it protected so your skeletal system is a major major player in keeping your body protected from external things great now finally I put on the inflammatory and immune response this is not necessarily a system of the body like these three are but it's vital in helping to protect ourselves so let's say for example in our skin over here you get damag so say you get a cut in your skin so now your skin is damaged and obviously things can start getting in pathogens can get in you can start losing water because now you're not insulated properly right well enter the inflammatory response so first off the inflammatory response deals with redness swelling pain and heat now you may say these don't help you right these actually make it really uncomfortable right well that's the point because when you get cut what will happen is a lot of these different chemicals will be released in that site of the injury there's a lot of different names for these chemicals one of which is cyto kinds which literally translates to cell mover chemicals what these chemicals do is tell different cells to move towards the site of injury these cells could be things like fibroblasts that will help build back that tissue that got damaged as well as macrophases which can help eat all the bacteria and pathogens that might get into it so that those cines cause some of these things but it helps draw important things to the area furthermore you can also see how your blood vessels are shattered and now you're going to start bleeding out and obviously we just talked about how important the blood volume is as well as a lot of different components so we need to stop that bleeding so what will happen is there will be a localized inflammatory response on the inside lining of the vessels this is kind of what it will look like so we'll say that's the side of damage right well when we expose this little end of your blood vessels it's called endothelial tissue and basically means the inner lining of the capillaries and that will expose a protein on the inside lining of these capillaries and that protein is called collagen and collagen is really really sticky for these tiny little fragments of cells called platelets so whenever there's an injury site we've got those cyto kindes right flying in here and we've got those collagen fibers presented both of which help the platelets find where they need to go and once they get there they continue to accumulate in that region forming what's called a platelet plug and once that plug is made there will be another protein come in here called fibrin that will secure that clot to the inside so you stop bleeding now there's a million steps to this process but it all comes in with that inflammatory response as well as the blood clotting Cascade so these are different ways that you can externally heal yourself as well as a little bit of internal healing in addition to all of those different immune responses that we talked about with the lymphocytes fighting off the bacteria and the viruses in the lymphatic system so amazingly your body has so many different ways to protect itself so now we've lived a good life we've kept ourselves alive we've protected ourselves we've maintained homeostasis in a variety of ways but how do we keep the human species going I think it's time for a chat about the birds and the bees all right male and female reproductive systems the whole goal is to produce Offspring but not only that we want to produce diverse Offspring that's the reason we actually reproduce sexually because we're combining male and female DNA into a zygote otherwise known as an embryo or developing baby and by doing so by combining two separate people's DNA we make a very diverse zygon very different from bacteria that uh replicate asexually where it's basically a exact replica or basically a copy of themselves whereas here we're making a brand new human super cool now in order to excessively diversify all these chromosomes we are going to go through a process called meiosis and meiosis is a type of cell division where the number of chromosomes that we start with will actually split in half so a normal functioning human cell will have 23 pairs of chromosomes what does that mean well chromosomes are just DNA organized into these little chapter books called chromosomes and so in each person male and female all of our cells have 20 three pairs of them where did they come from well here's a pair of chromosome ones this is a chromosome one from this person's dad and the other one would be a chromosome one from that person's mom so quite literally all of their cells in their body will have this type of arrangement one from Dad one from Mom when we get to chromosome two we'll have one from Dad one from Mom and so forth and so on 23 times okay same thing goes for the female this is that female's father's chromosome one and the chromosome one from Mom which makes sense because we are quite literally just a combination of our parents DNA right now keep in mind the goal though of meiosis it's to split the chromosome number in half why do we want to do that well if we split this person he has 23 pairs of chromosomes that's 46 right this person also has 23 pairs 46 total so we want to split this one so that there's 23 at the end so then we can combine it with the 23 from the end for Mom and then we can make the 46 total in the baby right so what's going to happen well this cell in the male is actually going to be called a spermatogonia literally translating to baby sperm and this is going to be called an oogonia literally translating to baby egg so baby sperm and baby egg great but what's going to happen here we are actually going to first duplicate the DNA on both sides so what will happen is we'll have one cell one's going to turn into the sperm one's going to turn into the egg and they will have twice the number of chromosome ones as well as twice the number of chromosome twos and so forth and so on 23 times over but that seems par but that seems paradoxical because we're duplicating the DNA I thought the goal was to basically just split them right in half right why can't we just split them imediately well if we just split them in half follow this logic if this one just became the sperm with 23 paired chromosomes what would baby be exactly like this person's dad and vice versa if this one just split and through the chromosome one from Mom and chromosome two from Mom and so forth and so on into the sperm this baby would be exactly like Mom you get the picture so we don't want our babies to be exactly like our parents we want them to be a blend of a lot of us right so what we do is we duplicate it and at this point there's an amazing process called crossing over that occurs and that's basically where these chromosomes are going to swap DNA amongst each other so each chromosome may look like this now so now each of the four chromosome ones that are in here all have a blend of both mother and father's DNA really fascinating so now once they're in those four on both sides so I can kind of draw an example over here we will divide these cells twice so we'll divide them once couple of those chromosomes will get passed on and then we'll divide them again to make four new ones each with an unpaired chromosome and the same thing will happen on this side I'm just going to skip some steps all the way to the end now so these four cells right will now have half the number of chromosomes so this is chromosome one in reality they have a chromosome 2 a chromosome 3 and so forth and so on but they're unpaired so therefore in total each of these have only 23 unpaired chromosomes and all four of them will turn into mature sperm cells wonderful now in the females case same way we've Diversified our chromosomes but only one of these four will be selected the females a little more choosy so this one once again has 23 unpaired chromosomes and this will turn into that o site which is basically the the mature egg cell and obviously if both of these two come together we have now formed our zygo with with 46 chromosomes and we could add 46 diverse chromosomes due to that crossing over right here and then the sperm and the egg that were produced have a blend of DNA from both their moms and their dads now fertilization likely happens up here in the Fallopian tubes of the female reproductive tract after being released by the ovaries during OV and once it travels down to the uterus it'll implant into the uterus and begin developing eventually into a whole baby that will then exit out the birth canal called the vagina and then you have that newly formed Offspring with a diverse set of chromosomes and that's reproduction y'all so here we are we've arrived and we have gone through 11 different organ systems throughout this video now I wanted to show this little pin wheel because all of these systems as you have noticed all contributed to one major factor in the body you can probably guess what it is homeostasis right now all in all I I starred two of them the nervous system and the endocrine system because both of these systems are basically acting as think of it the COO we're going to go back to my business model or the CEO and they are basically going to regulate all of these different systems in order to maintain that homeostasis so the endocrine and nervous are going to have them roll role in basically altering these guys' actions to ultimately keep your body functioning at a proper environment so you can stay alive now go ahead and check out the rest of the videos on this channel including these organ systems overviews where I dive into a deeper idea of each one and be sure to like this video And subscribe to the channel thanks for watching