Animal Physiology Lecture Notes PDF

Animal Physiology Prof. Mainak Das Department of Biological Sciences & Bioengineering & Design Programme Indian Institute of Technology, Kanpur Lecture – 01 An introduction to Anatom...

Animal Physiology Prof. Mainak Das Department of Biological Sciences & Bioengineering & Design Programme Indian Institute of Technology, Kanpur Lecture – 01 An introduction to Anatomy & Physiology Good morning, and welcome you all for the course in Animal Physiology. So, all those who have taken up this course: I have been teaching this course for a while and every time I teach this course new way of thinking about physiology. So, I believe again this time where I will be teaching giving you 60 lectures; that is a 12 week course and every week will be having 5 lectures which will be heard & seen across wherever our viewers are. So, I will be believe it will be another set of new experience about teaching Animal Physiology. So, whenever we talk about animal physiology there are few things which comes in mind; say for example, in our day to day life we hear several words relevant to our health. We hear somebody is having diabetes or somebody suffers from an accident had had a blood clotting or a hemorrhage, or somebody has urinary tract infection or as simple as diarrhea. So, these are several words which comes very frequently or a simple fever where the temperature of the body rises. So, some of us understand, some of us goes to the doctor and doctors explain certain things part of part of it we understand part of it we do not understand. So, the aim of this course will be to educate our self about our own body, in a very simple way. In order to understand our own body; say for example some bodies having diabetes. So, we all have a rough idea it has something to do with sugar, sugar is not absorbed or some issues, but what it is. Or when to have it hemorrhage; when we understand something to do with blood, but what is blood what is blood clotting, what is hemorrhage, what is sugar doing, what sugar has to do with diabetes. These are simple words, but physiologist will be able to put this word in a sequence so that it make sense to a lay person. That is precisely, will be my goal in this course whenever you come across a situation related to your body. You should be able to, if not diagnose you should be able to tell the doctor exactly what are the symptoms and where you believe if things are happening and of course, you can leave it to the doctor to think over it and diagnose it properly with series of tools, diagnostic tools to figure out what is happening. So, in a sense or say for example, let me give you another situation many a times doctors prescribe medicine and as the Indian citizen nature we never ask that nature of the medicine how it is going to react in our body. But, to tell you a fact from my own life while I was in U S I used to see that everybody used to ask the doctor and even I also develop that habit of asking the doctor how this medicine is going to work in my body, what it is going to do, and the doctor is compelled or it is part of that to explain this, because end of the day it is your body. But something what we will lack here in India is that we do not ask this question. Not asking this question is either you are fully trusting or you are really ignorant which is not good. It is good to know because I am not asking that you become a doctor, but at least you ask the doctor at least increase your understanding about your own self and that understanding can only happen when you have some basic understanding of basic physiology or about your body and how your body functions. So, once again let me welcome you all. Today is our first lecture. So, the first five lectures or the first week will lay the foundation stone of the structure of the course, in other word what all topics will be following in the first five weeks will give us a direction. So, I strongly recommend you all that go through these first five lectures very carefully, so from that point onward you will be able to correlate things at what level we are talking about; and we will come what I meant by level and complexities and what kind of control mechanism we will be talking about. So this first five lectures, and there will be some degree of all over at different times I will mention that wherever such a spell over takes place. So, let us enumerate what all topics we will be touching during this first week, during the first five lectures. So, as the title of the course Animal Physiology and we are starting with week 1. (Refer Slide Time: 06:41) So, these are the topics what will be covering during week 1. The first is: An Introduction to Anatomy and Physiology, second one will be The Chemical Level of Organization, next one is The Cellular Level of Organization- the (Refer Time: 07:51) the color so the cellular level of organization, next will be The Tissue Level of Organization, and fifth one will be the beginning of a system; the very first system will be dealing with will be Integumentary System. Now, as you see I have put three level of organization: a molecular level of organization or chemical level which will boil down to the basic molecules of life including DNA, proteins, lipids, and carbohydrates. Next level where these simple molecules self assembled to form the smallest functional machinery of our body called a cell, a individual cell and post that next level of organization where several cells perform a specific function and such colony of cells which perform a specific set of function is called tissue. So, there are three levels: chemical or molecular level of organization, the cellular level of organization, and the tissue level of organization and we will enumerate these different levels. And the first system everything integumentary system: in the first week of these five lectures what will be covering our major thrust will be on these four topics, and we will be closing on within integumentary system or if time does not permit we will move it on to the next week, but definitely our goal will be to understand these parts second out to this. (Refer Slide Time: 10:50) So, to start off with will be starting off with and introduction to anatomy and physiology. Let us move to the first topic: An Introduction to Anatomy and Physiology. Before I get into this topic I must say that these are specialty topics of biology and what really biology is? It is the study of life. So, when you talk about the study of life, we have to distinguish between living and nonliving. Say if we live into our basic understanding a living system, a life form has certain unique features. And if you have those features we call that as a life form, which includes there are certain parameters let us enumerate some of these parameters to start of it. I just now I talk to you about biology which is the study of life forms- life and its forms and functions. This is what biology is all about. And there are certain features of any living system and what are those features. Let us enumerate those features of living system. It has something called a level of organization, we will talk about that just few minutes back we talked about one level of organization: the chemical level, cellular level and the tissue level. Next is responsiveness, this organize structure is responsive. What does that mean? Responsiveness means a system respond to external stimulus. So, you are walking or you are standing somewhere, all of us sudden starts raining, so if will wet and either you get more into the rain or you run away from the rain- it means you are responding to the rain, it means you have sensors on your body by which you are sensing it. So, that is called responsiveness. Why this responsiveness is essential? It is a very simple term, but try to think slightly beyond the scope. So, we live in a system which is continuously changing, what does that mean? That means, we live in a system where the temperature is varying, where the precipitation is changing, where it may be possible that you are climbing to the pressure is changing and the system the organized structure which has developed it could be any life form is a function of these external changes, it has to adapt itself according to the changing environmental constrains. It may be very sunny, it may be very hot, or it may be very cold, or it may be very rainy, or you may be in the water, or you may be walking up in the mountains, or you may be walking down the slope, or you may be in a vehicle. So, based on the surrounding physical parameters which include temperature, a wind, oxygen level, precipitation, light, our body adjust itself. In order to adjust itself it needs to have a series of sensors on its surface, and these sensors respond to several stimulus; series of stimulus. We respond to smell, we respond to noise, we respond to light, we respond to touch, so many of these things and that is what makes us responsiveness. In other word if we considered in a diagrammatic way, if we considered our self this as this first circle as the system which is you me or any other living system. And if this is the surrounding, this is the second circle what I am draw drawing as the surrounding. So, the surrounding has lot of fluctuations happening, fluctuation like in terms of as I mentioned in terms of temperature, in terms of pressures, environment fluctuations or natural fluctuations. So, these fluctuations are sensed by the system and the system within itself this recalibrated it is a status. What does that mean it recalibrate? Suppose you are feeling very cold, do you like this, right? You are recalibrating, your system is generating heat in order to protect yourself; that is called a recalibration. But then how you do this? Say for example, outside you go outside the room and the temperature is very low, so all your sensors across this skin senses the temperature is low you started feeling cold so you start doing your hands like this, right. That is exactly is the whole process. So, that is called a responsiveness post reaction to a particular stimulus. That is what I meant by responsiveness. It is very important, that these words are very important. So, keep a tab try to think beyond that what does these simple words means. So, a system is responsive it can re or just itself according to the situation. (Refer Slide Time: 17:59) So the next the theme line is, third property of the system is it grows does a growth and differentiation. In other word we all grow, when we are born we are small and then we grow up and in that process we have develop several faculties within our system. We became intelligent, our nerve system grew up, and we develop our reproductive potential. There are several changes which are happening within the system and those changes are called, this is the this second word which is important which I am putting in yellow is the differentiation and the first word is the growth which means we are growing over period of time. So, in other word this is means there are changes in within your system with respect to time and space, your body space there are changes which are happening within you. So, in other word when you are born or rather let us even if you go back when you are conceived in the mother's womb, when you are born and as you grow old there are irreversible changes- mark my words ‘there are irreversible changes happening in your system’. Say for example, easiest example comes from nervous system. In your childhood if you are traumatized or your scared of something that memory continuous. Say for example, at some point you have a event taking place, your are scared of something. So, this memory will continue to haunt you all your life unless otherwise you do some means to get rid of it, but which is very tough, but you cannot wipe it away. In other word your system has already stored a piece of information at some point and it will continue to use that experience to modulate your next acts, you understand. So, if it happens today this event is going to modulate or influence your activities in the years to come, in the days to come, the next moment, because there is a permanent change, permanent imprint of that event which has taken place in your system. So, that is what it meant by in the time and space within your own system there are permanent changes and those changes are very critical, not only from survival instinct but from the evolutionary prospector. So, this is third aspect. So, let us number them A organization, B is the responsiveness, C is growth and differentiation. And let us move to the next one that is our reproduction. (Refer Slide Time: 21:24) So, for the success of a species: so remember this basic term rule- the success of a species is governed by the number of off springs we have, how much they can reproduce which determines their evolutionary success. The more you are more chances that you will gather more food and you will have more control over the resources. So, this aspect of reproduction is very critical from the survival and evolutionary success and equalogical advantage for an organism. And again this reproduction process is a time dependent curve. Just like growth in differentiation, so this process this happens at some specific point in a depending on the species when they become mature and they reproduce. The next aspect in it is movement; all living forms have some form of a movement including the plants. I am not talking about a plant is walking from one point to another, but they move towards sun light: phototropism, geotropism. These are following the gravity or following the sun, these are movement from one place towards a stimulus. Similarly, but again in case of human or other animal also movement is very discrete you really can see they can move. And these movement gave them a evolutionary advantage in terms of a avoiding their pray, avoiding their predictors, avoiding their enemies and hunting for food or going after the resources or gathering together. So, this movement has several benefits in terms of; and whenever I talk about benefits I talk about this word evolutionary benefits. How it helps in survival benefits, evolutionary survival benefits. So, these are not really benefits in terms of some financial benefits I am talking, I am talking about what are the advantages or benefits it accrues by having these features in built in its system. So, the next in that line is post movement is metabolism and excretion. So, metabolism and excretion these two are very critical. In a sense that biological system which is a self assembled unit of cells and tissues has the potential to either harvest energy by taking some energy rich molecules or it can directly harvest solar energy in case of plants. So, there are two kinds of systems: the plant and the animal. In case of plants they harvest energy directly from sunlight, and they convert simple molecules into carbohydrates. Whereas, those are called autotrophs; whereas we are heterotrophs, we consume these different plant material which are free with energy rich a or we can even consume animal proteins or animal fats and we convert these molecules to other bi products and in that process we harvest energy from them. And those bi products which are no more needed by the body are thrown out of the body. But this process of converting these molecules to different kind of bi products and extract the energy from it falls under a big topic called metabolism which is summation of two words: anabolism and catabolism. Anabolism is where small molecules are make to form a heavy molecule led in energy average bonds, whereas catabolism is the process where such big molecules had been broken down catabolic process. And the system is equate the machinery by virtue of which you can throw away those bi products or waste products which body does not need. So, these are basically the features which are defined for a living system. And as we will go through you will realize all these things will come one-by-one that well you talk about physiology of different systems. So, this is our first lecture when I am closing today. In the next lecture we will talk about the different aspect of physiology, different level of organization as we remembered in the very first fragment I have showed you organization. So, will be in the very next lecture we will start with different level of organization and different functional aspect and different classification of an atom. Thank you, and once again welcome you all for this journey in to our own body. Thank you.  Animal Physiology Prof. Mainak Das Department of Biological Sciences & Bioengineering & Design Programme Indian Institute of Technology, Kanpur Lecture – 02 Organization of Living System Welcome back to the second lecture in Physiology. So, in the first lecture we talked about the basic characteristics water living sustain should have, or the foundations what has been laid out during last 200 years how we define a living system. So, there we talked about they should have some basic criteria which includes organization, they should be able to grow and differentiate. They should have some movement feature they should be responsive to the external stimulus, it should be able to reproduce and above all there are irreversible changes which happen in the system. So, what today we will do we will start from those words and define the different terms anatomy and physiology. (Refer Slide Time: 01:19) So, whenever we talk about, if you remember we talked about this word and I told you to highlight this word the organization. So, we will start from here we will be starting our lecture two essentially from here from this particular word. Let us move on to the new slide. (Refer Slide Time: 01:41) So, today we are into lecture two; lecture two I told you remember that word called organization. Now, whenever we took talk about organization. So, think of it. So, if you look at an elephant it kind of gives you a something, if you look about a human being something like this or we talk about a small rat or mouse something with something like this or we talk about a fish it will be like this. So, if you look at these different organizational setups you see different kind of structures. So, all living things have different scheme of organization. So, what we use the word is see for example, these are the different schemes what have been followed by living systems, scheme of organization. And based on this scheme of organization they have different anatomical aspects or in other word their external structure. So, if I have to put it straight across it will be like this organization is nothing but is telling their anatomy and anatomy could be at two level their internal structure and their external structure; we will come to that internal structure and external structure. So, if we talk about the external structure you can already see this this has a different kind of external structure different kind of external structure, but inside this there are different kind of internal joints internal features which is making this to walk with four legs in the case of human beings two legs whereas, this does not have any leg it swims whereas, these have four legs arranged in a different way. The external features external shape determines it is internal structure, and again at what level you are studying it. If you are looking at it this this is called the gross anatomy. So, anatomy itself could be classified into different class, it could be either gross anatomy or it could have if you bring down narrow down your zone of looking we started looking at the very cellular level at the cells which are making it, then we call it a microscopic anatomy. So, gross anatomy could be at different level. So, what are the different levels of gross anatomy? Gross anatomy could be classified or at least could be studied at four different levels. First level is the surface anatomy, surface anatomy where you studied the surface features see for example, in case of human we are having hairy bodies in the case of fishes we have a scales in the case of elephants they are a different kind of a small hair like structure similarly in the case of rats, they have a fur like structure in the case of dog depending on which race which species we are talking about they have different kinds of furs structures. So, that is the surface anatomy followed regional anatomy regional anatomy means different aspects say for example, your digestive system of a human being as compared to a horse or as compared to cow or a fish; if you do a comparative physiology of these things these fall under the regional physiology of that particular part that particular system. Next come systemic physiology systemic anatomy sorry systemic anatomy and then comes developmental anatomy. So, we talked about surface anatomy and we talked about the regional anatomy and we talked the systemic anatomy, where you see the whole system as the whole a different system. Say for example, here you have the cardiovascular system, nervous system, respiratory system, excretory systems. So, these different systems how they are placed along with the other one and how they interact with each other, what are the different level of their interaction that is what we studied under the systemic anatomy. Next come is the developmental anatomy or the developmental changes. So, if I take you back to the previous slide there in the last class we talked about the growth and differentiation. So, I told you over a period of time as a living system grows from conceiving it in a mother’s womb, then taking birth, and then going and become aged. So, in that process there are several changes several anatomical changes which are taking place, and these anatomical changes is and these anatomical changes started in the mother’s womb starting from development of the body structure, development of the different organs. And then the systems followed by their cross tog, and then making a whole system and then with age how they are changing. So, these are all falls under developmental anatomy, the changes during the developmental phase. And this also includes post developmental changes, which includes the changes which happens post development like you know once you are born. So, developmental changes followed by post developmental anatomy. So, as we grow old as we are ageing there are changes happening in the anatomical feature at the cellular level at the bone level those are post developmental anatomical changes which are taking place, sometime they are very very important from the perspective of studying the pathology studying the development of disease or how our ageing system changes with time, and what are the necessary precautions which you take to ensure the safety and integrity, and proper functioning of the system. So, that falls under the post developmental anatomy. So, these are the broad gross anatomy classification. The next comes the microscopic classification anatomy there we talk about at different level. The first level is the cellular anatomy, when you are studying anatomy from the cellular prospective that includes different kind of cells within your body you have nervous cells they have a different structure, you have a liver cell which have a different structure, you have heart cell which is a different structure, you have a kidney cell which is a different structure you have reproductive organ cells which have different cells. So, you can study the anatomical feature from the very smallest functional unit which we call as cell. So, cellular anatomy which is the microscopic level and then next level is histological; where you take a section of a whole tissue so, cellular or cytology pertaining to cell histology pertaining to tissue. So, what you do see for example, you want to study the tissue of the heart. So, you take a section small what we mean by section is see for example, all of you have seen cheese or say for example, the kind of you know removing a wrapper of you take a Cadbury or any kind of chocolates. So, you remove the wrapper it is almost like the thin wrapper, you are removing from something and you take that wrapper under the microscope and you study the anatomy. Those anatomical studies falls under histology, histological studies and they are one of the very powerful tools to give you knowledge about the next level of organization from cellular to the tissue level of organization, how in the organ these cells are arranged together what are the channels of their cross tog between individual cells. And how they interact with the environment you get an idea about it before you move into the next level will be this systemic anatomy which is at the gross level. So, if you see you can study the system depending on. So, what is important to understand the one critical word and that critical word is this one scale at what scale you are studying the system. If you are studying the system at the cellular level at the level of the cell then you are studying the system at micron level. So, cytology is we are talking about micron because average size of a biological cell if it is an r d c we talk about or so anything it varies from 5 to 25 micron. A neuronal cell body say for example, a neuron we talk about which will be around 25to 30 micron a standard one there are one switch have differences which are much more larger or smaller. So, at the level of cellular level we talk about anything between I would say 5 to 20 micron scale. Next come histology where you have studying lot of cells in one spectrum. So, here individual dimensions will still remain 5 to 20 micron, but you are getting a much more larger area to study. So, we move into the millimetre level something like you see the section in front of you know, 1000 microns sections in front of you. So, you increase the scale slightly higher then comes gross anatomy where you physically have to take a scale in centimetre or meter where you are studying these systems. So, it is all about scale and when you talk about development it is all about time with respect to time. So, when we talk about scale we talk about space, what level in a space what is the smallest unit in space you are measuring and when we talk about the changes in that space we talk about time. So, in other words the real time anatomy is the study of time and space of a system, at what dimension of the space you are measuring and at what time you are measuring, because all these system if you remember my previous lecture I mentioned it very clearly these are all changing in a irreversible manner. In other word these are all following something called non equilibrium thermo dynamics where a system is changing permanently, you cannot go back to it is original point because from original point it has deviated there are changes which are happening into it and those changes are permanent. You cannot really reverse the clock to go back that ten years back this is the situation I wanted to go back, that will never going to happen it will be a reversible system which initially organized itself and then it is started increasing it is complexities over a period of time, it develop it differentiate post differentiate and eventually a point come and it integrate itself at an optimal energy level and then a point comes where it disintegrates what we call as death. And during this whole process anatomy of the system changes at different level whether it is at a cellular level, whether it is even if you go down, whether it is a molecular level whether it is at the cellular level whether it is at gross level in other word which is at the level of surface regional or systemic level there always changes happening. So, next what we will do. So, by the way this gross anatomy is used by the doctors for another set of classification which is missed out let me put it together again. Where they use the medical anatomy is basically they the doctors initially look at the gross anatomy then there is something called a radio graphic anatomy, those goes through all sorts of radio graphic tests and then there is called surgical anatomy. All these three things have clinical relevance in terms of the clinical setting, because the doctor who has to treat you or has to give you say some gamma radiation some other radiation or something to remove say cancerous lump or a mass they have to know the exact location within the body where they are putting the radiation so that falls under radio graphic anatomy. Medical anatomy is that how you are defining which part which tissue which angel and the three dimensional space say for example, just you will appreciate it. Say for example: this is how the heart looks like with four chamber hearts. So, now, say for example, there is a problem somewhere here or somewhere here. Now, this structure is three dimensions something like this. (Refer Slide Time: 19:56) It is a three dimensional structure: now something is somewhere inside. So, with reference to a scale you have to know in three dimensions where the problem is then only you can target the problem. So, those things falls under the medical anatomy where you should have a three dimensional map of a structure of anatomical structure, you know exactly you should be able to pinpoint say for example, I have to give a radiation somewhere in this say for example, this is a mammary tissue or some other tissue where there are cancerous growth. So, I should be know, and I suppose this is my radiation emitting probe. So, I should be able to know exactly where the radiation is reaching. If I move up and down or sidewise I am going to damage a whole lot of thing I may be able to lose track of my exact target and the patient may die because I am unable to locate pinpoint exactly where the tumor is where the cancerous cells are. So, this all falls under the radio graphic or surgical as a matter of fact even in in surgery. Suppose I am doing a laser based surgery I wanted to you know wipe out that particular part. So, unless I know in a three dimensional structure, where I have to really point the laser I would not be able to do it. So, you realize that understanding anatomy is very very critical from multiple walk of life. Those who are interested in physiology has to understand anatomy back and forth without that starting from clinical applications to other changes you would not be able to figure out. So, these are some of the clinical classifications of anatomy. Now, we talk about a system as of now we have talked about a wonderful system like you know this whole system, now this system has certain governing dynamics or certain rules of functioning. So, before we get into those rules of functioning what we will do is we will do a bit of a classification of physiology as a unit. So, what are the levels of physiology we can study? So, we talked about anatomy. (Refer Slide Time: 21:17) Now, we will talk about physiology and it is level physiology. So, you can study physiology at the cellular level we talked about cellular anatomy now we are talking about cellular physiology, you can study physiology at the level of organ like you know organ level physiology then we can study at the systemic level physiology or we can at the pathological level. So, these are different level where you can study at cellular level, systemic level or at pathological frontier and when you talk the organ level this is also sometime we use the word called special physiology. Where you talk about say for example, I want to study the cardiac physiology. So, I am exclusively studying this. So, when we talk about the cellular say for example, within cardiac physiology I wanted to specifically study the cellular nature of say cardiac myocytes or ventricular myocytes. We will come to that do not worry about these words or within the kidney I wanted to study the cellular structure of a nephron. So, that falls under cellular physiology or a systemic physiology where you are seeing the interaction of different systems or pathological physiology this is one way you can classify it. So, then what you can do what are the level of organizations. If you remember we talked about the organizational level. So, let us draw the organizational chart level of organization. So, the level of organization could be organization of system could be at multiple level, the first level what we talk about is chemical or molecular level which is the top of the parameter chemical or molecular level of organization. Next is cellular level of organization at the level of the cell you can study a cellular physiology third higher organization is the tissue level of the organization where you talk about the histology. Fourth is the organ level of organization where the different tissues form an organ. Next is when different organs interact with each other organ system physiology and final one is the organism level of physiology and if you draw the pyramid it will be something like this, this is how the pyramid will look like. So, now at what level you are studying it determines what kind of information you are going to get. You can study at these different level you can study the anatomy and physiology, you can go even further deeper a interaction where the current trend is study at this level some are at the cross road the chemical and the molecular and the cellular level next level comes if you are studying the physiology at the tissue level anatomy and physiology. Third at the organismic or at the organ level, fourth one is the interactive level organ system level and the final one is the organism level the whole system you are studying in one go. So, whatever level you study you have to realize that you have to correlate it back in that pyramid from the chemical to the molecular aspect all the way to organism. So, this is how the system works. Now, there are certain governing rules. So, there are different level of control systems which are happening at different level at all these different level and those are called different feedback mechanisms. So, what we will do now and the next class we will discuss two aspect, one how a system respond what are the basic thumb rule for a system to respond; and once it responds how it react to it. In other word it has a responsive element and then it has a reactive element and we will come to that what are different feedback loop systems which are functioning which include a negative feedback and a positive feedback. After that what we will do was a study about the reference say for example, what I meant by reference is say for example, I have to study a human body. So, what will be my scale reference how I am going to study it will I study say for example, you look me from the front there are certain features you see in my body you look me from the side you get certain feature you see me from the back you get certain feature. So, all the organs say for example, this is one organ. Now, depending on which angle you are looking at it you are looking from that side my view also looking from that side I am looking from back say for example, I keep it like this. For you see it is a there is nothing alright if I show you the back it is like this, there is a huge hole out here. So, from which angle you are studying it are you studying it like this, are you studying it like this, are you studying it like this, are you studying it from my angle like this. So, these brings us to different planes sagittal plane coronal plane and we will talk about that how you are studying the system in other word that brings us to the basic fundamental of what is the scale you are following, how you are determining the scale and where you are positioning your reference point, what is your reference point of looking at this system, are you looking at this angle, are you looking at this angle are you know dissecting the system like this or you are dissecting the system like this. So, we will talk about next two things we will talk about the feedback controls of our system and then we will talk about the different sectional geometry by which you can study a system, and that will pretty much brings us the point that we can initiate to a study any of the organ systems. Thank you.  Animal Physiology Prof. Mainak Das Department of Biological Sciences & Bioengineering & Design Programme Indian Institute of Technology, Kanpur Lecture - 03 Homeostasis & System Integration Welcome back to the third lecture in the animal physiology series. So, in the last class we talked about the organization, we talked about the different classification of anatomy; the gross anatomy, the microscopic anatomy, in terms of cytology in terms of astrology then we talked about the physiology at different level at the cellular level if you remember the pyramid what we meet the chemical level, cellular tissue level, organ level, system level and the organismic level. Now, when we talk about a system every system every living system is calibrated to function at certain optimal physical parameter; what does that mean? Let us take a example of human body where most of the reaction or almost all the reaction takes place in a aqueous medium; in other word in a medium of water most of the reaction takes place at a temperature regime of 25 to 35 degree centigrade, body maintains optimal temperature in and around that range. We can withstand a certain amount of pressure beyond that we are having problem we are adapted to live at a specific oxygen tension as well as at a Co2 tension beyond that we will be having trouble. So, in other word, the dynamic systems are tuned or fine tuned to function within a narrow or slightly broad window of physical parameters now if there is a change in those physical parameters what do I mean by that see for example, your body is adapted to withstand say thirty degree centigrade fine. So, suppose your body function. So, if the temperature of the surrounding rises to say 45 degree. So, automatically the outside temperature is very high. So, automatically your body will absorbs a lot of heat. So, from thirty degree optimal temperature it will go up. So, in that situation body has to re calibrate itself this is one example. Or say for example, your body is adapted to live a at a specific oxygen tension and suppose you are claiming mountains as you are claiming higher and higher and as the atmosphere is getting rarer and rarer the oxygen tension reduces at a higher fortitude there is lack of oxygen. So, automatically because the lack of oxygen you will be inhaling lesser oxygen. So, under that situation your body will have to recalibrate itself in order to ensure or compensate for that lack of oxygen which is not available because you are at different ecological needs. Similarly, if you go down the ocean down you are doing scuba diving or something else something of that sort where there is no oxygen and the pressure is high how you adopt to that high that hyperbaric or hypobaric pressures. So, all these situations we will point to one aspect that body has a mechanism by virtue of which it can recalibrate itself and the process which is involved in it is called homeostasis. So, today we will talk about how the body maintains its homeostasis what is the basic feature what are the basic component which helps in maintaining the homeostasis what are the different kind of feedbacks systems which are involved in it. Mostly there are 2 feedback systems negative feedback loop and positive feedback loop and apart from it we will talk about some of the examples of negative feedback and positive feedback. (Refer Slide Time: 04:57) So, let us start the class with which is our third lecture; lecture 3 and the topic what will be dealing today is homeostasis and system integration homeostasis and system integration what this word homeostasis means if you break this word into 2 parts say for example, you said homeo as the one word and stasis as the second word. So, homeo means unchanging; unchanging which is not changing plus stasis means standing. So, the body maintains its status or re-calibrates it and this whole process is called homeostasis. So, in other word in a simple language if you put it; that means, existence of the stable internal environment existence of stable internal environment internal environment this is what is meant by homeostasis and a homeostasis is the one which leads to what we call as system integration a system gets integrated because a system can recalibrate itself by different mechanism in order to allow it to function. (Refer Slide Time: 07:24) So, now from here where let us move on to the next slide where we will talk about what are the different mechanisms of homeostasis. So, homeostasis could be classified into 2 parts one is the auto regulation or intrinsic auto regulation or intrinsic homeostasis and the second one is extrinsic homeostasis and example of such things say for example, if it is auto regulation or a intrinsic say for example, we have tissue and this tissue is say for example, this is used to with a particular concentration of oxygen x concentration. So, now, x minus y concentration of oxygen now this tissue is receiving. So, it means here is this minus y reduction in the optimal concentration say for example, I said five unit oxygen is needed per minute now you are getting 3 minute of oxygen per minute it means there is a deposit of 2 unit of a oxygen which is there what this tissue will do. Now, in this situation what this tissue will do is here are blood vessels which are bringing the oxygen to this tissue and will come later into that how these are designed and everything. So, what it will do these blood vessels which are present there sensing that there is a lack of oxygen here they will secret certain things all by themselves by sensing lack of oxygen or x factor this factor x will change the diameter of the blood vessels originally the diameter of the blood vessel is like this if this is the d the original diameter d o which is the original diameter post secretion the diameter will become like this which is the new diameter d altered d a. Now, what will happen the amount of blood which will be supplied to this tissue will be more and this more blood which is being supplied to the tissue will compensate for that minus y amount of oxygen which is the deficit amount will be compensated by this dilated vessel and the blood supplied through that dilator vessel. So, this is an example of auto regulation on maintaining the homeostasis. Now, what about the other one when we talk about the second example which is extrinsic situation extrinsic is a situation which is controlled another control of mostly not always true, but just for your initial understanding sake is another control of the nervous or the endocrine system see for example, there is a flame. So, for example, there is a flame here and by mistake you put your hand there. So, automatically there will be a burning sensation. So, immediately what it will do a nervous system will govern the mussels here to immediately remove it contract and will try to localize the effect in that region it will not happen that if you do. So, that all over your body you will have the burning sensation. So, it will confine that burning sensation at that specific location. So, this is governed by a nervous system or the endocrine system or sometime by both of them. So, this is one example of it similarly when you are doing exercise another example let us talk about it when you are doing exercise. So, when you are doing exercise your consuming more oxygen. So, for example, lets write it down you are doing exercise you are consuming more oxygen and if you are consuming more oxygen this will tell the heart to pump heart pump pumping will become more and the heart pumping is more automatically there will be more blood flow which will compensate for the lack of oxygen. So, in other word these are the process by virtue of which a system is broad band to its original state and that is what we meant by homeostasis. Bringing back to its original state or trying to maintain it status go where it was. So, now, from here what we will do. So, I am giving to you example the auto regulation or intrinsic process and the extrinsic process where the nervous system and the endocrine system is controlling it. (Refer Slide Time: 13:32) Next we will talk about what are the components which are bringing about this homeostasis component of homeostasis let us talk about those components in homeostasis. So, the component in homeostasis are you first off all needed a sector first thing we needed a receptor which acts as a sensor we will come to that then you need a control center third important thing you needed a effector which will take care of it and will give the examples of each one of these 3 situations. So, your receptor is basically a sensor sensing a specific signal or stimulus sensor sensing a specific signal or stimulus your control center is doing the work of integrating this signal integrating and processing the signal and your effector is executing the processed signal. So, these are the 3 component. So, before we proceed further I will give you an example from our day today life say for example, I am standing in this room at this point if I see the air conditioner board it will panel show that this room at as we maintain at a temperature of say to any 4 or 25 degree centigrade it is here air conditioner room where I am standing. So, now, what will happen if the temperature of the room all of a sudden goes up suppose there is a wend pipe from a lot of heat starts coming inside the room a lot of hot air is grown inside the room. So, the room temperature thermo stasis set of the air conditioner is saying that it has a 23 degree centigrade. So, if the temperature of the room goes up from the 23 degree centigrade. So, automatically there will be a thermo meter which will sense it and once this thermo meter senses it, it will tell the thermostat or the effector mechanism that there is increasing temperature then what this will do this will tell the effector which is the air conditioner to get operated and bring back the temperature from what is over it rises from 23 degree centigrade and it will bring it back to 23 where the 23 or 26 where the temperature of the room has been set. (Refer Slide Time: 17:23) So, this is in a way we can call it, it is a feedback system let me draw it that will make more essence to people it is a example out here I have a normal room temperature normal room temperature say I would like say like 25 degree centigrade now for somewhere other normal condition is disturbed normal condition disturbed the normal condition is disturbed. So, there will be a stimulus and there is an normal condition disturbing in other word there is an say for example, there is an increasing temperature. So, what will happen this; this temperature will be monitored by. So, in the form of receptor in this case there receptor will be a in aliment object which is a thermometer. So, thermometer senses that there is an increasing temperature of this room what this will do this effect there is an increasing temperature will be transmitted information to the control center or thermostat setting info information to control center or which is also the thermostat setting thermostat setting. What the thermostat setting knows it its sends a command signal from here a command signal is will be relayed by the thermostat send sends command signal to effector and this effector then turns on the air conditioner see here air conditioner is on now that increase temperature whatever that delta increase what has been happened here. So, that delta increase will be brought down out here. So, the room temperature drops to set point and in this case your set point is 25 degree centigrade it will brought and this will eventually normal condition will be restored which is again 25 degree centigrade normal condition restored. So, this is the kind of feedback role what we use in any kind of engineered systems and these feedbacks are all inspired from biological systems biological system exactly follows these kind of feedback think of a situation before I explain in terms of what happens. So, for example, you are running after running all of us sees like you are a perpetration lot there is all your shirts and everything kind of get wet there is huge amount perspiration happening why is it. So, what is the reason that when you are run after that lot of heavy exercise and there is a huge amount of perspiration lot of sweat and everything. So, there is a feedback mechanism which is helping you. So, let us dissect all physiology have to understand it is all about dissecting the situation what possibly is happening in your body as long as you have that analytical ability to break the problem into small wet some pieces physiology will be a cake walk. So, you have to have a very strong analytical bend to break a problem and that is something will cultivate over years after years through your studies through real life situation a good doctor is the person who can analyze he or she listens to the patients and based on that the analytically break down the problem possibly this and based on that they prescribe medicine prescribe test or make the diagnostic whatever they feel. Now, let us break this problem what just now I told you lets go to the next page and try to you know dissect out the system what is happening. (Refer Slide Time: 22:47) Now,. So, simple example let us see now we talked about the normal outside the system now will talk about homeostasis in a biological system homeostasis where normal body temperature t degree centigrade. So, now, this normal is disturbed out here say for example, normal body temperature disturbed it could be any reason now let us assume that your running normal body t degree centigrade disturbed. So, your stimulus here is rising body temperature you are running stimulus is rising body temperature this is stimulus will be sensed by certain receptors and these receptors are present on your skins as well as in hypothalamus I will tell you what is hypothalamus. So, these temperature T degree centigrade sensors are present on your skin and hypothalamus. So, where is hypothalamus? So, hypothalamus is a region of the brain pretty deep inside this is the part of my brain pretty deep inside you like you know draw 2 pins some from here someone in the centre there is the small organelle which is called hypothalamus which is newer in the crime system that is the temperature controller So, not only my skins are sensing that there is a increasing temperature there is hypothalamus which also sense there is a increase in the temperature once this happens what will happen. So, this info or this information there is an increases in temperature goes to the different control centers. So, here is the control center what we are talking about. So, I told you where is hypothalamus; hypothalamus is. So, this is the brain is which going and hypothalamus is sitting somewhere out here somewhere just out here. So, this info is reaching the hypothalamus which is essentially is that control enter control center and this is the thermo regulator center this is also called a thermo regulatory center. Now, at the thermo regulatory center this hypothalamus sends a command signal sends a commands this command signal reaches the effectors. So, I told you there will be receptor there will be control center and who are the effectors here, now let us enumerate the effectors who are involved in this game effectors are sweat gland which sweat gland in skin increases the upward arrow are showing increases the secretion of sweats that is why use sweat a lot. And second thing what happens is blood vessels in the skin dilates blood vessel in skin dilates was these 2 things happens dilation means there is a increase in the diameter of the blood vessels just suppose if this is the original diameter in the green this is d o and this red color is showing d, d dilated diameter and based on this, this leads to 2 things happens after this post sweat gland in a skin increases specious and response and it leads to there is a increased heat loss from the body because our body temperature is high increase heat loss through evaporation because your sweating a lot as well as your blood vessels have dilated. So, your evaporation surface area has gone up and second there is a increased heat loss through radiation again that is because you have a more surface area and this eventually leads to what we called as normal temperature restoration and this whole mechanism is a negative feedback loop. So, this is how a negative feedback loop helps in maintaining the homeostasis in temperature is it clear to you guys think over it whenever you sweat whenever many such. So, you see what we try to do we break the whole one thing that the body temperature rises because of exercise and we started sweating. And then we build the whole story and this is exactly what I expect from you people from this moment onward as one as you listen to this lecture is you start dissecting think what are possible could have happened is the temperature rises what will happen if the pressure rises, what will happen if the pressure falls what will happen or if there is too much light, what will happen if there is too much heat what will happen. So, these are the parameters what you have to do and then based on that there are several levels of in like you know complication you know receptor the molecular structure of the receptor the cellular structure of the receptor there is. So, many levels the organismic level what is the receptor size within the control center how this circuit is functioning how this is getting transmitted what is the mechanism of transport how from this center the effector is been connected what is the structure of the effector at the cellular level at the molecular level and so on and so forth and how this whole system is integrated into one loop. So, this is one example of negative feedback in the next class what we will do we will talk about the positive feedback just the reverse of it feed forward and we will talk about the frame of reference of studying anatomy and physiology. Thank you.  Animal Physiology Prof. Mainak Das Department of Biological Sciences & Bioengineering & Design Programme Indian Institute of Technology, Kanpur Lecture – 04 Positive Feedback Loop in Homeostasis Welcome back to the fourth lecture on Animal Physiology. In the previous lecture, we talked about the negative feedback system. So, if you recollect to we talk about if the temperature of the body rises, how we act on it, what are the sequence of events. Similarly, if the temperature of the body falls how we act to it I wish you guys should be able to an explore that if the temperature falls what are the reactions we have one of the reactions is if the surrounding temperature is very low you know we do this kind of motion like you know what does that mean it generates heat and what all are the other things it will be just the reverse of what you have just seen what happens when the temperature rises. So, this is the way I wish that you should develop your physiological thinking or logical thinking of the events which happens in your own body and in the surrounding and based on the surrounding even how your body reacts of course, when you talk about the surroundings we mean surrounding inside the body surrounding outside the body it means even if there is a change inside your body how your body is going to compensate for itself suppose you take a food which is very acidic how your body is going to react to it or you take very alkaline how it is going to react it. So, overall when we concluded the last class that take home message which I conveyed to you is it is a dynamic system and the dynamic system interacts with the surrounding and based on the surrounding changes this dynamic system which is our body it recalibrate itself in order to adjust to the newer settings. So, keep this thumb rule in mind and basic physiology is nothing, but understanding the structure of these dynamic system and its corresponding functions of these different structures which come together to form a complete system what is a human body or a animal body or any kind of microbes or any kind of living systems. So, today we what we will explore we will just talk about a reverse situation a positive feedback which are very few which happens positive feedback in our body with; there is one example which I will give you, but detail molecular mechanism we will be talking about it when we will talk about the blood clotting it, it is something to do with blood clotting and from there we will move on to the different sectioning of the body before we move on to the overall layout of chemical organization tissue level organization and the cellular level of organization; sorry it should have been molecular level or chemical level organization cellular level organization followed by the tissue level of organization. (Refer Slide Time: 03:29) So, coming to this class which is so, this is our lecture four here we will be talking about positive feedback loop positive feedback loop and this positive feedback loop what we will be dealing today will be mostly related to the situation of blood clotting. So, say for example, I will tell you a situation say for example, there is a break in the blood vessels. So, let us think of the real life situation what happens when there is a break in the blood vessel you fell down or you have a scarve; you see the blood whose as out from that place right, because the blood vessels gets ruptured capillary is gets ruptured soon after that what you see after while in the blood do not come out from that mode slowly the blood is stops to come out and eventually you see some form of a small semis. So, solids kind of you know structure which is formed there which we call as a clot and over period of time as days passes by that clot becomes harder and harder and as all the tissues of the damaged location kind of repair itself the colt at tissue which has become already very hard sluft off from the layer or it kind of you know falls out from there. So, this is what you see whenever there is a rupture of the blood vessel due to any injury due to any accident due to any scarve or whatever you know this whole process you can translate in terms of engineering in a simple way as if there is a pipe which is carrying water and there is a leakage in it and somebody has repaired the leakage it is almost similar to that. So, in your body there are blood vessels which are carrying blood all over your body for some x y z impact those blood vessels at some a specific location got ruptured and itself heal itself. So, this process is called a clotting process. Blood clots, but then this is what you observed, now let us break the problem of what call even which takes place. So, let us put them in the way we put earlier. So, break in the blood vessel which is the first event what you observe break in break or rupture you can put it break or rupture in blood vessel causing bleeding at a specific location in your body which leads. So, say for example, in a real life what is happening these are the blood vessels which are supplying blood all over your body and say for example, there is some rupture which happens here. So, the blood started to ooze out from that location. So, this is the blood which is falling now as soon as the blood started oozing out from this location. So, this part is the damaged tissue what we are talking about the this location which is your damaged tissue or damaged blood vessels as well as the surrounding tissues surrounding tissues means all this location these are all surrounding zones what I am drawing is in the orange coloured. So, these damaged cells they secrete certain specific chemicals I am not getting into the details at this time well we will talk about the blood clotting I will tell you what are those chemicals they fall under intrinsic and extrinsic process of clotting these chemicals leads to the process of clotting to begin beginning of clotting process. So, as we are breaking down from the problem you see this one was the step one, this is step two and these kind of secretion of chemicals happen both from the damaged blood vessel as well as from the damaged tissue around it because when you get an impact. Say for example, on your body it is not only the blood vessels which gets ruptured it is the mussel it is the endothelial it is the epithelial cell it is the endothelial cells they also get damaged. So, these are the once which secrete those x y z chemicals what do you see out here what has been highlighted out here in the in the picture. So, these chemicals start the process of clotting which is the step three followed by clot this clotting process initiate a positive feedback it means this clotting demands for more clotting reagents to come into the place additional chemical release and this additional chemical release accelerates, because the process of clotting I am showing the acceleration with this four upward arrows clotting accelerates and eventually this leads to the final goal blood clot plug breaks in vessel wall and the bleeding stop and this process what is happening is here is a positive feedback. To summarise the process we got an impact at the impact zone there is the rupture of the blood vessel as well as the damage of the surrounding tissue. So, now this vessel has to repair itself the first reaction who takes place is the blood vessel the damaged blood vessel as well as the surrounding tissue starts secreting certain x y z chemicals these chemicals initiate the process of clotting and it sense a forward message or in other word a positive support that you secret more chemicals. In order to completely seal the vessel where the rupture has happened and this positive feedback leads to the sealing of the vessel. And final result is the bleeding stops and followed by as I was telling in the beginning the surrounding tissue and everything appears and we seal it and the body functions normally. Now, we have two examples one of negative feedback in terms of thermo regulation in the other one is the positive feedback in terms of blood clotting. So, now I will recommend you people look for other positive feedback loops which are existing in our system which that is almost like think of it that. You know there is whenever you remember these kind of things or visualise it is almost like at a zone there is a war zone there a small platoon or a small number or small regiment which is fighting against it and they ask for more reinforcement you send us more reinforcement, because we have injuries positive feedback exactly works like that that you know you send us more and more reinforcement we need to you know recover out, because we are out of our resources. So, with this I wish to highlight another very interesting aspect of physiology is that our whole body actually function on negative and positive feedback loops and these loops are very important whenever you have to dissect out a situation the first thing you should do you should be able to draw them in like a blog diagram and it should be able to make the connectivity what all are happening and at different point you will have different measuring technique to see whether this output is increasing over period of time or this output is decreasing over period of time say for example. If you look at this picture what just now I draw how we can really quantify is it a positive feedback or a negative feedback. So, at every level say for example, at this level we have to quantify if you quantify with respect to w r t with respect to time you will see that these factors are all increasing. It means there is a positive feed forward loop which is functioning. So, you see in this simple diagram there are lot of not only qualitative feature, but there are lot of qualitative as well as quantitative features involved in it. So, as a matter of fact tomorrow’s physiology is more of a quantitative physiology because everybody wants to know that how much say for example, I want to emulate the situation. Again, let us get back to the in diagram say for example, there are I say there are say chemicals these chemical release may be say A B C D E just for your understanding say there are five different chemicals which are secreted. Now, I will be came to know what will be the concentration of these chemicals which will be secreted at this specific zone. So, you know the damaged area say for example, I know x x square or x cube unit in terms of vessel if I have to go I have talk to the volume in that volume how much of these chemicals are released. In other way what you are trying to figure out is the space out here is the space what we are talking about and release of chemicals second thing. So, this is the space damaged space the types of chemicals and the most important out here is this part with respect to time. So, you realise all the phenomena are function of space and time. So, when one can quantify a phenomena with respect to space and time then one can say with certainty the limits of a system why this is important you might ask the question other way why really we needed to find out these details or the find prints these find prints are very important say for example, you have heard that soldiers getting injured in the ballet fields and they get hit by bullets or shells. So, what happens those; those situation the first thing which have most of them have suffered from heavy wounds heavy wound means there is a huge amount of blood vessel which gets ruptured say for example, out here. Let us again come back to the picture for you to visualise say for example; here I showed a very small zone with the red with a red circle. Now imagine in this blood vessel the damage is this big this is the amount of damage which I am showing in green huge say for example, ambulate injury or huge shell hit out there bullet injury or you know now for this injury now this is space constrains now what you see in terms of damage the space what we talked about x cube. Now this becomes x plus x cube plus a huge area some you know y cube and the chemical concentration what will be coming out what you say will also have to change and not only that time which will take. So, the more bigger the injury site is the more complex this equation, because if you know for this much unit area or this much unit volume this is the amount which is release could we recalibrate it what is the limit of the system is it repairable within that period of time that the person will on die and what are our therapies. So, there are people who work on several bio materials who try to you know seal those big raptures in the blood vessels specifically for deference applications specifically for those heavy injuries which takes place because a shell and all those kind of things. So, you see a small problem, but you can think you can stretch your imagination to a different level to see where it go all impact us. So, this is what I wanted you people to think beyond whenever I say think beyond I mean I can teach certain things in the class, but that you have to think that will it be possible to make this repair that they are or will this forward feedback loop or a negative feedback loop we will act for a bigger area because this is where comes from physiology to you. So, this is what you see whenever people talk about making patches you know blood vessel patches and all these things which is essentially. One second that me write down blood vessel patch is. So, this is what we are talking about physiology to what I call it as engineering or material science material engineering or bio engineering which. So, you will like to you know address yourself it could be a bio engineering it could be a material engineering or tissue engineering or bio materials. So, in order to understand any of these things one has to have a clear idea how the physiology is taking its own course and what are the limits of a system. So, as I told you in the very beginning like this four courses I will try to kind of you know pin point certain things that where I expect you people to think much bigger much broader. So, these are some of those points where you should be able to think that where I can apply this where this information is important, because you know we teach many things, but many a times we forget to make our students aware that where you really can apply it because you know just importing a piece of information is not sufficient what are the implications of it. Next what we will do after this. So, as of now we talked about a system and I say for example, I say like you know this is the system I wanted study and this is the anatomic system how I am going to study it what are the reference points today we will talk about all the reference points of the study references of studying a body reference point mention it. (Refer Slide Time: 22:02) So, what are the reference points? So, say for example, or in other word you can call it a frame of reference for anatomical studies frame of reference for anatomical studies. So, say for example, you are standing sideways. So, this is your standing. So, this part, for example, if it if you look at me. So, I am standing like I am standing now sideways now if you look at the side ways you can see this picture. So, if you stand in a sideways this is how it will look like how we put the reference this is the cranial part the front of your body this is called anterior or ventral part for body the back of your body is called the posterior or the dorsal part or the dorsal part and lower part which is called the caudle part of the body now if the same person instead of standing sideways is standing to the front ways. So, for example, hand. So, if you are. Now, in that situation the upper part of your hands say for example, this part of my hand as you look at me this is the part which is called the proximal end you can see this. So, this is called the proximal end and where you have the digits and everything this is called the distal end. So, we will come across these words and this part of the bodies called the medial part similarly the side walls which is the arms and everything these are called the lateral part. So, these 2 are opposing each other lateral and the medial is basically anything to do with the central part of the out here whereas, the lateral are on the sides. And now, similarly lower part of the body you have in terms of the legs this is the proximal part p and this one is the distal part and there is 2 more words which are used upper part of the body is called the superior and the lower part is called the inferior. So, the words which will you come across very commonly will be the proximal end the distal end. So, always remember proximal is this part distal is the this part central part of the body which is the medial part and side which is the lateral part lateral now back of you is the posterior front of you is the ventral or the anterior part remember this much this is good enough the cranial part and the caudle part. So, this is how you remember and then we will come to the different planes by which you can do a sectioning of a system so for that; move on to the next slide. (Refer Slide Time: 26:58) The different kind of sectioning what you can follow the sectioning, I will only talk about three different sections which are a major importance to you people sagittal section transverse plane and frontal plane. So, say for example, what is sagittal section? So, sagittal section is essentially say for example, I am standing here you make a cut like this like this. So, part of you make the nose into half one half on the; this side another half on this side you make a straight cut like this on my body right, so that is called a sagittal section. So, half mouth on one side half mouth other side ear one this side another ear on this side you make the cut of the brains like this like this; this is called a sagittal section. So, draw it, it will be something like say for example; so you are cutting the body like this. So, this is your nose in a sagittal section part of the nose on this side part of the nose on this side, this is your lips. So, it will be cut like this. So, this is called a sagittal plane. Next is the transverse plane transverse plane is that it you are cutting the system like this say for example, this is the whole body in your cutting it like this. So, that is called the transverse cuts like this in other word it say for example, this is the cylinder and I give a transverse cut. So, these are the transverse cuts which are coming out. So, this is the transverse cut then comes a frontal cut frontal cut is; is very interesting frontal cut is something like area of cut it like this. So, in the frontal cut you are cutting this system in a its something like this hold on your sagittal cut is coming like this and when you are doing a frontal cut it will be something like this you are cutting it like this these are. So, for you what is the important is the sagittal cut and the transverse cut and on the other side what you needed to remember is the proximal distal medial lateral and ventral and the dorsal and of course, the crenel caudle superior inferior. So, these are few words of reference point which I wish you people to remember for a rest of the course because that is good enough we do not need go to the in the detail of medical anatomy because we do not need that for this course, but as long as you could remember the reference frames right it we are good to go. Thank you.  Animal Physiology Prof. Mainak Das Department of Biological Sciences & Bioengineering & Design Programme Indian Institute of Technology, Kanpur Lecture – 05 Chemical Basis of Organization of The Body Welcome back to the lecture series in Animal Physiology. Today we will be starting the fifth lecture. So, just to have a little recap what we did in the last fragment of the fourth lecture. So, we talked about the references or the way you study a structure a dynamic structure like human body or as a matter fact any animal system what are the different planes how you cut it. So, we talked about the three different planes sagittal plane transverse plane and the frontal plane this is where we kind of wind up and earlier to that we talked about the lateral part proximal part superior inferior distal and proximal and medial part lateral part and all those terminologies. So, when I wind up in the last class I kind of felt that the frontal plane I should have explained it much better for you people. So, when you talk about the sagittal plane I told you that you are giving the cut like this. So, half of the nose in one side half of the nose in another side half of the mouth is one side and another mouth is another side then when you talk about the transverse plains you are taking the head. So, you are cutting the body like this you know like this. So, you consider body of the cylinder and you are cutting the cylinder like this now talking about the frontal plane where I fell that in a little bit of a more understanding is that when you are making the cut like this. So, suppose you give a cut like this. So, in the first cut you will have the nose eyes and everything the next cut you will have the part of the brain and is a good back all of the cut of the rare. So, that is what we call as the frontal cut. So, these are the different ways by which a three dimensional structure is being studied. So, every section what you get you study the anatomy histology of that section and then likewise you add all of them and then you figure out the three dimensional structure. So, there is lot of imaging processing which goes on in modern days anatomy because this is exceptionally essentially say for example: as I was telling you in the last class on a three dimensional object. So, for example, a cylinder somewhere in a space at a particular x y z coordinate there is some e element. So, how you locate it you needed reference point. So, you really have to image a person section by section. So, having said this these are the olden days how anatomy has been has been studied by the modern days anatomy is more on the side of imaging noninvasive imaging techniques how without damaging the system you can image the whole inside thing it is almost something like an x ray what we do when you pass through the scanner you know you are getting scanned by the x ray similar to that, but that only can do for the hard tissues not for the soft tissues. How we really can image a system without destroying it and there is enormous amount of research which is going on all over the world for non invasive imaging techniques and this is one of the most challenging area falls under a multiple expertise starting from optics to imaging to mathematics to image processing and to advanced camera and advanced microscopy. It is a very very interdisciplinary area, but area which will flourish in the decades or the centuries to come because one of the things just think of it say for example, in your body blood is going. So, it means it is just like you are taking a remote sensing image or something from the top you can see river is moving exactly similar to that within your body blood is moving it is come from the heart it travel all over your body comes back to the heart. So, now could you have imaging scanner which can tell you at what speed blood is moving. So, even without checking the pulse without checking the blood pressure just you can be able to visualize the flow of blood in a real system without doing any inviscid application. So, this is where modern days anatomy with if you those who are aware of Grey’s anatomy these are very old books and almost biblical in terms of the way it had shaped the modern day medicine by the modern days anatomy is heading more on a different frontier which is of course, basic anatomy has changed, but much more life into it; it is no more ecstatic subject it is a very very dynamic subject and why not think of it a cancerous tissue grows or a lump grows, it is a dynamic system it is not a static system at some point it is happening. So, those of you who have a player to enjoy image processing or who have a player of reconstructing three d image from 2 d slices they may explore what all modern days medical anatomy or as such anatomy as such can offer and there is another component to that the death for any object there is a depth components. So, you just do not have x and y it is the three dimensional objects. So, if there is a depth component and how you know major all these things having said this- today we will move on to the molecular organization followed by the cellular organization and followed by the tissue organization of a body. (Refer Slide Time: 07:18) So, let us move on to the next slide. So, in lecture 5, today we will be dealing with. So, let us put in. So, we are in to lecture 5. And the first thing today we will be dealing with is the chemical level of organization. So, in these three sections what we will be dealing with I will kind of you know brush up your basis the chemical basis of organization of the body organization of the body. Now if you look at it we all are made up of atoms and molecules and nature has picked a very simple atoms to design us in respect of carbon in respect of nitrogen in respect of hydrogen in respect of oxygen apart from it, it has picked up few other transition metals like iron cobalt manganese molybdenum. But in a very small amount and these different molecules or these different atoms eventually form molecules and these molecules have self assembled some of them are complex molecules some of them are simple molecule they have self assembled to form their structural component of our body and some of these molecules standalone has formed the framework or the conditions or the base where all the reactions of our body takes place some of these simple molecules have taken part in synthesizing much more complex molecules. So, just if we kind of what I will be doing here, I will be outlining all those different molecules which are involved in the chemical basis of the organization of the body. So, while outlining. So, just now I talked you about we are having series of atoms and molecules and if you look at the different atoms which are involved carbon nitrogen oxygen hydrogen iron manganese molybdenum magnesium chloride sodium potassium there are handful of them which dictates our system. (Refer Slide Time: 10:26) And followed by that most of these atoms are bonded with each other by different three different kind of bonds bonding of atoms here I am just kind of you know brushing basics because eventually while I will be going through the detailed course all these things will come very handy. So, you will have the ionic bonds where full filled transfer of electron taking place then you are having the covalent bonds and then you are having the hydrogen bonds these are the key things which you have to revise and I wish to request you please pick up any biochemistry or any go to any online just read couple of sentences about them. Because, we will be asking some small questions on these things multiple choice of course, on these things what are the ionic bonds what are the covalent bond and I am not going to get in depth into it because these are been covered in several courses, but we will be needing all this things. So, it was just kind of give, you a refresher here. (Refer Slide Time: 11:48) So, these are the points you should know. So, from here we move on to what are the basic. So, all these different kind of molecules goes through a series of chemical reactions RX stands for the reactions and they could be either irreversible or these are reversible and one more thing which I just forgot in the previous like to mention you these covalent bonds could be further classified into non polar and polar covalent bond. So, among the example polar covalent bond is like water which is a polar molecule and non polar covalent bonds are the one which form the framework most of the molecules which form the framework of our body this is the some of the points you should remember and coming back to the next slide you are having series of chemical reaction in the form of reversible irreversible chemical reaction and the roles of enzymes and this process. So, what I expect from you; you should of course, will be talking about the specific enzyme as we will be moving like if enzymes like carbonic anhydrase nitrogen. Agen series of them we will be talking as we will be moving through, but just have an idea at least a very fundamental idea what are enzymes. How the enzymes function what is k cad value and all those kind of things I just wish you guys to can I go through that as a part of yourself assignment to brush all these basic concepts the roles of different kind of enzymes followed by that. We talk about the different kind of inorganic compounds which are involved in our system, and the major inorganic compound which plays a critical role is water inorganic acids and bases sodium hydroxide. So, I am talking about water all our reactions in the body the medium is water that is why we call it aqua system all the reactions all the reactions you can think of all have the medium as water then we are having a series of salts starting from sodium salt chloride salt potassium salts magnesium salt. Likewise then we are having the series of buffer systems for p H control these are very important as we will talk about the different kind of buffer systems in the kidneys in the lungs in the blood these different buffer system. So, what I expect from you people you should know the basic very very basic of what is p H what is a buffer and how these different buffer systems regulates the p H of the body these basic knowledge I expect you guys to know brush during this process these are all you know you all have studied all these things in your school level. (Refer Slide Time: 15:58) Next from here we move on to we talk about the organic compounds again this is the basic biochemistries first chapter the different organic compounds which are involved which includes your carbohydrates. So, I expect you to know what are the common carbohydrates you have the lipids we will talk little bit about more about lipids as we will talk about the bi lipid membrane in the cellular organization then you have the proteins; proteins could be classified 2 level it could have a structural proteins as well as you have the functional ones of course, both are functional. But these are the ones which I had taken part in direct reactions, and these are the one which are forming their structural components then you have the genetic machinery which is run by the nucleic acid and they have a specific locations within the body and then the most critical one energy compounds like ATP, ADP and NADPH like ATP, NADPH, NADP, FAD, likewise these are the difference of course, the most critical one the most important one is the ATP. So, what I expect you people to kind of know the different kind of carbohydrate specially why glucose is. So, significant lipids in terms of the classification of lipids you pick up any biochemistry text you will you will figure out nature of polar head groups and a non- polar tails the different kind of lipids which are present in the neurons in the brain ceramides go through any text book you will figure that out. And we will talk about the proteins what is alpha helix what is beta sheets these are the confirmation alpha and alpha helix and beta sheet confirmations we talk about the different structural proteins like collagen carotene in terms of the functional we will talk about the different kind of enzymes except of course, one of them which is a nucleic acid enzyme. Then different other proteins which has different kind of functional roles then we will talk about the nucleic acid what you people get to know are the RNA and the DNA and the energy compounds and where all their involvement when we talk about the energy compounds. (Refer Slide Time: 19:18) We come in the very next slide about the different cell organelle where they are concentrated all these different kind of molecules from here we move on to cellular level of organization cellular level of organization. So, the big is prime of life form which is evolved on the floor of earth or wherever in the universe is the self assemble ling of certain unique molecules to form a confined structure what we call as cell. So, say for example, suppose I will just represent that these are the different these different colors what I am going to are assume these are the different kind of atoms which are there in the pre biotic soup k all different kinds of atoms which are present there and this is the pre biotic soup billions of years ago out here at one point by some physical forces of nature or something somewhere or other there is a self assembly which occur these could be complex molecule. These could be simple atoms, these could be molecules of lipids or something and they form the first confined structure what we today call modern day as a cell and this cell is formed by the self assembly of lipid bi layer. Just few minutes back I was telling you I want you guys to know about the polar head group of the lipids and the hydrophobic tails. So, here is a hash part is the; should get this is the polar head group which can interact with water where as the tail which I am showing in blue is the hydrophobic part. So, the biggest tramp was or is how the self assemble to form my structure and on such as structure they; they develop systems of continuous different kind of transport mechanism energy dependent transport uni-directional transport bi directional transport channels they form a series of channels here sodium channel potassium channels chloride channel water channels and all these channels are of course, made up of a proteins as well as they have marker molecules on top of these channels have them to identify which are of carbohydrates. So, if you see a memory in itself sorry; this is proteins which are forming channels gates pores pumps. So, what you see just in the previous slide if you go back. So, all these different molecules what you see there is one thumb rule which has given all of them they all have self assembled somewhere rather and we do not know how these different lipid molecules or as a matter like the proteins how the self assembled what made them the formation of the peptide bond what their situations how such a long chains were formed. How the DNA evolved we do not know we do not have a answer to these question in the pre-biotics how these molecules were formed we just have no idea because this is far and beyond in the time where we start saying the DNA, but how DNA evolved because if you look at the cell in the left side I just give this let me draw a classic cell when you talk about a classic cell if it is a in mammalian its mostly a spherical shape. (Refer Slide Time: 23:41) So, this is the membrane what just now which is a bi lipid layer and even nucleus inside within the nucleus you have the nucleic acid in a and this is the nucleus and this is the lipid bi layer membrane l stands for lipid bi layer bi l stands for the layer lipid bi layer membrane. Then you have another organelle called mitochondria which is taking part in all the energy production machinery of the cells if it is a plant cell of course, you have chloroplast which is harvesting the sunlight. So, it is a very complex structure what we talk about as a cell it is a very very complex structure, but how this complex structure evolved is a one heck of a tough question we really do not know how it has evolved, but what we know are these though we do not know the origin of it, but what we know is it forms a membrane. (Refer Slide Time: 25:16) And this membrane has a semi permeability it does not allow everything to go in or go out it has a lot of transport rules and regulation. As I was telling you it could have diffusion it could have facilitated transport and this part what you see here this is called the cytoplasm between the nucleus and this is cytoplasm, and these are the different organelles. Again I am not going to in depth of it because I want you guys to you know brush your basics on this. And here you are having the nucleus which is regulating your development and heredity all these features all the different aspect of a unique cell type are being conserved in this DNA and through the expression period each cell changes its forms. And then finally, rest at a final form before it you know dies out and there are certain cells in our body which remain intact throughout our life which includes nerve cells cardiac cells likewise and if this is the cellular level of organization. The last in the final level of organization what I wish to highlight here is these cells from different kind of tissues which is called the tissue level of organization. And at the tissue level of organization what we are having there are four different kind of tissues we deal with mostly which is epithelial which is forming the cover of the all the covering- say for example; all the surface these are all epithelial cells of a body one. The next one is connective tissue we will talk a lot about these connective tissues as well as epithelial cells in the sections to come connective tissues are different kind they could be something called a proper connective tissues they form a structural framework of our body. Then we have fluid connective tissue which includes the blood and the lymph then we have supporting connective tissue which includes your bones and cartilage and the very next section post integumentary system. We will talk about the bones and the cartilage. Third important tissue classification is the muscle tissue muscle tissue could be classified into three groups and we will separately deal with them which includes a skeletal muscle cardiac muscle skeletal. I do not need to tell all the muscles which are present in the body are the skeletal muscle the cardiac muscle the one which is handling your heart and then you have the smooth muscle which is lining the gut of the body and the fourth and final non regenerating one is called the neural tissue. So, we will have individual sections in each one of these things and of course, later we will be dealing with the tissue injuries and aging tissue injuries and aging is the process where you know things different shapes. So, what I wanted to highlight here while closing in on this class is that this is the framework where from molecular self assembly at some point during our evolution cells are performed. The cells learnt a machinery to divide and replicate and conserves it information in the form of nucleic acids and at some situation may be in the form of proteins they could conserve information. And they further develop in to very complex structures of tissues these tissues join together to form organs. These organs joined together to form systems and different systems form together or join together to form what we call as a body. So, with this brief introduction of 5 classes of different level of organization we will be hitting the subject from the mostly from the tissue level of organization well or rather the organ level of organization. So, next class we will be on integumentary system followed by the bones and the cartilage. Thank you.