 So, let us resume the lecture on NPTEL on physiology and especially we are now dealing with endocrinology and reproduction. So, we initiated with the overall architecture of the endocrine system which consists of hypothalamus which is sitting at pretty deep into the brain, which is controlling the pituitary which is one of the major endocrine gland and we talked about the thyroid, parathyroid, adrenal and the gonads and the pancreas. So, I give you an overall view or overall position of these different organs and we talked little bit about the structure of the pituitary which consists of an consists of two parts anterior pituitary and posterior pituitary and we talked about that anterior pituitary receives the hormones from hypothalamus via a local blood vessel. Whereas, posterior pituitary which is also called as neurohypophysis is another name for that, that receives that does not have any blood vessel to receive hormones from hypothalamus, hypothalamus directly have neuronal projection on the posterior pituitary on the neurohypophysis and those neurotransmitters which are secreted or those hormones which are secreted because of the nerve signals are then transported from neurohypophysis or posterior pituitary via a blood vessel to its target organ. So, with this what we will do we will talk about the intricate circuit between the hypothalamus and the pituitary. So, let us talk about that circuit. So, today we will resume with the circuit between hypothalamus pituitary here it is worth mentioning that yesterday when I showed you that how the higher centers of the brains are regulating hypothalamus. So, hypothalamus depending on the situations sends two kind of signal either it will say it is a inhibitory signal or it will send a stimulating signal or in other word you can also call the stimulating signal as releasing hormone or inhibiting hormone. So, say for example it is like this. So, pituitary has to say for example, secret a particular hormone say x. So, pituitary needs a signal from hypothalamus. So, when pituitary has to secret x then pituitary will release will receive a signal called x releasing hormone from hypothalamus. So, x r h and when pituitary does not need to secret that particular hormone then pituitary from hypothalamus will receive a signal called x i h which i h stands for inhibitory hormone. So, it will say you do not secret that particular thing. So, it is kind of a very tightly controlled loop and what tells hypothalamus is could be the downstream metabolites and everything which are produced because of x. So, it is kind of a very nice feedback loop. So, what we will do now what I will enumerate are all the inhibiting and releasing hormones secreted by the hypothalamus which influences pituitary or dictates pituitary is role in the further down the cascade. So, let us enumerate the hormones which are released. So, let us put that at two different level. So, this is the level of say hypothalamus the first box the second box as the pituitary box and then we will put all the downstream cascades which are there. So, these are the different neurons which are present in hypothalamus because just. So, now here is the blood vessel which is reaching the pituitary this is the blood vessel. So, the first one which will be which is release releasing hormone is called prh pro lactane releasing hormone or p i h. So, this is pro lactane and r h stands for releasing hormone i h is i h stands for inhibiting hormone. So, pro lactane is involved in different kind of milk production and all those kind of situations. So, then this provokes pituitary to release pro lactane this is all about anterior. So, I need to we are talking about anterior pituitary pro lactane then reaches its target and x does its function target tissue same way the next important very very important hormone is called growth hormone g h r h stands for growth hormone releasing hormone and g h i h stands for growth hormone inhibiting hormone. So, these hormones when growth hormone releasing hormone when it reaches the pituitary it promotes pituitary to secrete growth hormone. Growth hormone has wide range of function in all our growth related activity and it has target pretty much all over our body. So, there is rarely any such place where you would not find a growth hormone releasing hormone growth hormone receptors. Then comes the next set of hormones which are extremely tightly regulated in terms of a reproductive maturity and everything these are called g n r h gonadotrophin releasing hormone g n stands for gonadotrophin and the hormones which are secreted by the pituitary in response to gonadotrophin releasing hormone are f s h and l h f s h stands for follicle stimulating hormone follicle stimulating hormone and l h stands for leutonizing hormone. We will talk about this hormone while we will be talking about the reproductive aspect of human system and these f s h and l h which are secreted by the pituitary let us do the secretion of the different sex steroids by the gonads. So, their major target are the gonads there are other targets, but at this point we are only talk about the gonads not to make things complex and here you will see there is a gonadotrophin releasing hormone, but I am not showing any gonadotrophin inhibiting hormone because this is under the feedback loop of some of these have different feedback loops at different level and apart from it the sex steroids which are produced have the feedback loop. Then we talked about corticotrophin releasing hormone and all the three hormones now what I am I will be talking about they do not have any inhibiting hormone here this is called c r h corticotrophin, corticotrophin releasing hormone and corticotrophin releasing hormone leads to the secretion of ac t adrenocorticotrophin and by the antideed pituitary and then this leads to the secretion of the cortisol and cortisol secretion takes place in adrenal which will be covering very soon adrenal gland which is present in the kidney on top of the kidney then you have called t r h thyroid releasing hormone t stand for thyroid. So, this thyroid releasing hormone reaches the pituitary and pituitary release something called thyroid stimulating hormone sh is the stimulating hormone then thyroid stimulating hormone reaches the thyroid gland and leads to the secretion of the t 3 and t 4 and all other thyroid hormones. So, now if I summarize it so at the level of hypothalamus so this is the hypothalamus level. So, hypothalamus is secreting almost seven different kind of inhibiting and releasing hormone prolactin releasing hormone prolactin inhibiting hormone growth hormone releasing hormone growth hormone inhibiting hormone gonadotrophin or the reproductive releasing hormone corticotrophin releasing hormone then t i r h thyroid releasing hormone and the anterior pituitary is secreting and I am not talking about posterior I will talk about it later because these are the situation where all the signals are coming through the blood vessels this is those local blood vessels. So, anterior pituitary is secreting prolactin growth hormone follicle stimulating hormone leutonizing hormone a c t h and t s a thyroid stimulating hormone. Now prolactin has it is target is a very specific hormone which is involved in kind of milk production and everything whereas growth hormone has a wide target all over the body and whereas g n r h has it is major target through a secretion of f a follicle stimulating hormone and leutonizing hormone to the gonads which are mostly responsible for all our sexual behavior and sexual development. Whereas c r h corticotrophin releasing hormone it leads to the release of a c t h from the adenocorticotrophin from the anterior pituitary which act on adrenal gland where the cortisol is being released and this cortisol has wide range of function which will be coming very soon. Whereas the t r h thyroid releasing hormone leads to the secretion of thyroid stimulating hormone from the anterior pituitary thyroid stimulating hormone goes to the thyroid where thyroid is being thyroxin is being synthesized and that thyroxin then shows it is function all over the body and if you look at it overall so if you come to this particular slide again. So, you see at every level there is a feedback loop which is function. So, higher centers of the brain which receive signals from all over the body they ask hypothalamus to secrete inhibiting or releasing hormone then this acts on pituitary from pituitary it acts either directly on different systems or at different second or third tier of endocrine systems and which again sends feedback loop. So, it is a complete feedback loop of neuro endocrine. So, you can pretty much call this kind of situation as a neuro endocrine axis it is a long axis where this these are the the higher centers of the brain are the neural component of it and the whole endocrine. So, this whole neuro endocrine axis plays a key role in almost all the physiological processes which happens in any of these living systems especially human being or any other mammals or life forms and it is a very well coordinated system and they get affected by several ways as before I move into it. So, say for example, you people must have heard this you know the traces of pesticides in the crops which we eat leads to endocrine misfunction or endocrine disruptor and endocrine enhancer. You see sometime people have hair growths in unusual places or some kind of other ailment because most there are several compounds which are currently used in the food products or during food production in the form of pesticide insecticides or some other you know growth stimulants or anything which we are not even aware of how they are influencing this neuro endocrine axis and it is so tightly regulated that those picomolar or nanomolar traces once they enter inside our body they create havoc and all our endocrine system comes under intense stress because of this. So, with this I will move on to it is just kind of giving a bit idea bit of idea that why we are now kind of you know why FDA or any other food and drug administration of any country is kind of very concerned about what we are adding to the food because that is the major source because whatsoever we eat it is eventually from the blood vessel those are being absorbed by different parts of the body and that is what eventually influences all your function. So, these are some of the things which I appreciate if you people go online and check what are these you know endocrine disruptors how they kind of you know influences and sometimes they can even lead to this is like cancer or other neurodegenerative diseases and slowly we are trying to understand how different factors are influencing different endocrine or neuro endocrine functions. From here let us move on to the posterior pituitary and I have as I have already told you that posterior pituitary is directly under the neuronal control of the hypothalamus. So, it does not unlike the anterior pituitary which is being supplied from a local blood vessel from hypothalamus in case of posterior pituitary it is not. So, and the two hormones which are involved in posterior pituitary are one of them is oxytocin the other one is ADHD. So, now let us draw the circuit for posterior pituitary. So, here you have the hypothalamus hypothalamus and here you have the posterior pituitary I am just putting it P P for your. So, here is the direct neuronal connection and from here this is the blood vessel which carries the secretion or hormonal secretion by the pituitary. So, one of them is oxytocin the other one is ADHD anti diuretic hormone these are the two hormones which are secreted by the posterior pituitary oxytocin has two major targets one is the breast the other one is the uterus. These are the two places where oxytocin majorly acts and ADHD has one of the major target is kidney and what it does in the kidney as well as in breast and uterus. So, let us come to that the function of ADHD is it acts a response to hypothalamic osmoreceptors. In other words when the osmolarity changes in the body or there is a excess loss of say water or some kind of metabolites this leads to the activation of the ADHD specifically in a situation where there is a there is a increase concentration of sodium. So, increase permeate. So, what basically it happens is that it once again ADHD leads to the increase the permeability of the come to this distal tubule of kidney distal kidney and collecting duct and ensures more water reabsorption and it is the thereby maintaining the optimal level of sodium. Optimal level of sodium ion is being maintained by anti diuretic hormone and it basically ensures when there is a body is running out of water it ensures that you know it is being restored. So, this is one of the major function what is the function of oxytocin oxytocin stimulates the contraction of smooth muscle. This is essential during childbirth when the fetus has to come out. So, this is specially in the uterine muscle sometimes oxytocin injections are given because that leads to the movement of the fetus from the uterus and specially it is done in cows, buffaloes or even in human being where the small dose of oxytocin helps the women to you know allow the fetus to come out slowly oxytocin also helps in milk release from the breast during the time of breastfeeding because it increases the contraction of the muscle because of its action. So, there are response to that how basically it gets regulated. So, these are the two major functions of oxytocin and adh whereas adh is regulating the water concentration and thereby maintaining the right sodium concentration and kidney plays a very critical role and once we will be talking about kidney again touch this point how adh is playing this role and oxytocin which directly acts on the uterus as well as in the breast in the breast it ensures that the milk is being released properly during breastfeeding and uterus it ensures that fetus slowly and gradually moves out of the women body during childbirth. So, these two are very critical for our development now from here after. So, now we have kind of covered the hypothalamus and the pituitary and we have talked about an uroendocrine axis from here I will move on to the adrenal which is under the regulation. So, if you go back I just so this is your so this is this is the part I am going to try now talk about talk to you this is the part this is the part of the where corticotorofin releasing hormone leading to the secretion of acth by the pituitary anterior pituitary and then this anterior pituitary is working on the adrenal gland which is so the location of the adrenal gland is out here from this. So, if this is the kidney from where the this is the kidney. So, here is the adrenal gland sitting. So, this particular gland has a very interesting structure if you look at this structure if you see the cross section of this this is something like this it has outer core and it has a inner core if you take a just a cross section like this and the outer core. So, if this is the inner core and this inner core is called medulla this is called the medulla and whereas, the outer core consists of three layers outermost layer middle layer and the inner layer and all the three layers have different functions and we will come to that the most inner most layer is called zona reticularis the outer most layer is called zona glomerulosa and the middle layer is called zona fasciculata these three layers have three different secretion and the inner layer has again a different secretion. So, medulla is involved in the secretion of catecholamines catecholamines I have introduced the term catecholamines, but catecholamines are what you have studied in the autonomic nervous system nor epinephrine and epinephrine. So, I told you that epinephrine and nor epinephrine also functions as a hormone. So, the medulla is involved in the secretion of epinephrine and nor epinephrine whereas, the other three layers zona fasciculata zona glomerulosa and zona reticularis are involved in other different other secretion. So, the inner most layer which is your zona reticularis this layer zona reticularis is involved in the secretion of androgen and we will come to the individual function of it whereas, zona the middle layer the zona fasciculata this here zona fasciculata this one is involved in the secretion of glucocorticoids and the outermost layer which is zona glomerulosa is involved in the secretion of mineralocorticoids and the major mineralocorticoids secreted by zona glomerulosa is aldosterone and the major glucocorticoids secreted is cortisone. So, these are this is the kind of the functional structural functional distribution of the different layer of adrenal inner most layer the medulla first layer which is the adjacent layer to the medulla which is the zona reticularis which secretes androgen then the middle layer which is called the fasciculata which is secreting glucocorticoids or cortisols and then you have the outermost layer which is zona glomerulosa which is secreting your mineralocorticoids or aldosterone. So, now what we will do we will talk individually about that different of these corticoids. So, another important thing for you people to realize these corticoesteroids are all synthesized from one of the very potent molecule called cholesterol they are all synthesized for cholesterol and if you remember while I was talking about the membrane structure we talked about the cholesterol and told you it is a very very important molecule and it has multitude of function starting from modulating the fluidity of the membrane and other things it has one of the major function is that it is involved in the synthesis of corticoesteroids. So, now we will move on to the mineralocorticoids. So, the mineralocorticoids we will talking about the aldosterone what mineralocorticoids are. So, in the outermost layer mineralo. So, one of the major function of mineralocorticoids is it maintains the normal concentration of sodium and potassium in extracellular fluid, maintain concentration of sodium and potassium in ECF extracellular fluid. The next major function is that I already told you aldosterone is the major mineralocorticoid and it is stimulated by the secretion of mineralocorticoid is stimulated by first increase potassium concentration in extracellular fluid this is one factor the second factor is increase activation of and I will come to that this renin angiostentense system while I will be talking about kidney at this time I am just bypassing it and then when there is a decrease in sodium in ECF extracellular fluid and when there is a increase in ACTH in blood these are the four situation when aldosterone secretion is being enhanced. And what is the function of this how it works function or effect call it effect. So, what it does essentially is that again coming back to the membrane what I taught you it effect the sodium potassium pump of kidney. And in other word what it does during that situation it helps to by regulating this pump it as I told you just before this slide there is a increase concentration of that ensures that kidney get rid of brings down the potassium concentration and maintains the sodium concentration. So, this is the way mineralocorticoid work from here we will move on to the glucocorticoid glucocorticoids which is in the middle layer of the adrenal glucocorticoid is involved in the metabolism of this is extremely important in terms of metabolism of carbohydrates fats and proteins and it is a cortisol is the major I have already told you cortisol is the major glucocorticoid which is present and it is stimulated by this is very important it is stimulated by first situation when it is stimulated is the acth level in the blood again regulated by pituitary acth is regulated by cortic corticotrophin releasing hormone which is coming all the way from the from the hypothalamus. And this response happen during some specific situation and this is very interesting it mostly happen during extreme emotional stress this is very interesting to understand when there is an extreme emotional stress. So, especially in the situation of trauma starvation and anxiety so coming back now if you try to look at it very holistically. So, here is a situation when a person is in extreme stress in terms of you know some kind of a trauma or anxiety or a fear or something. So, for example, that is the time when some of the areas like amygdala or other heart centers of the brain gets affected. So, those centers sense a signal to the hypothalamus hypothalamus leads to the secretion of corticotrophin releasing hormone corticotrophin releasing hormone travels along the blood vessel comes to pituitary antitrary pituitary. From antitrary pituitary acth is secreted this acth come all the way to the adrenal from adrenal in the from the second or the middle layer of the of the cortex of the adrenal the glucocorticoids are being secreted. So, you see you see it is a kind of a very interesting loop it is a fantastic chemical circuit which is regulating all this processes and any deviation from this just because of some kind of stray chemical which is entering your your body or some other situation could really hamper this very neatly balanced chemical machinery which is functioning for ages now and it has adapted to the changes of human life in a very interesting manner. So, let us talk about that how after talking about this let us talk about the the function or the effect how it works on them works on the body. So, what is essentially does is that increase level of cortisol leading to the skeletal muscle to break down the protein and releases the amino acids into the blood this is the first thing which happens. So, again again I am using track of the slides the next thing happen is that it dictates the lever to increase glucose production through a process called gluconeogenesis. So, this is the second thing which happens and we will talk about gluconeogenesis as all we will be talking about the digestive system and this is in other word you can call it it is a fuel mobilization process and this fuel mobilization effect is a very long term effect this is not something it is a short term effect it is a fairly long term effect this glucose mobilization. Then comes within the medulla you have this sorry before the medulla you have this adrenal androgen which is secreted by the innermost layer this is basically a sex hormone it is a male sex hormone and it is not as potent as the pure like testosterone which is secreted by the gonads, but this has a role in mostly the role it plays is in sexual behavior not in sex sexual development, but especially in the sexual behavior this particular hormone has a role to play. So, this is very important to realize and then we talk about the we go back the easy talking about the medulla which is secreted in the catecholamine the epinephrine and norepinephrine we have already discussed about the function of epinephrine and norepinephrine in terms of they are involved in increasing the heart rate they are involved in myocardial contractility they are involved in other different kind of lipolysis function or the breakdown of the lipids. So, if I had to summarize this whole process if you look at it. So, this adrenal is playing a very extraordinary role under the influence of at four level of influence higher center of the brains which are controlling your anxiety fear energy requirements they dictate hypothalamus hypothalamus dictates pituitary pituitary dictates adrenal and then adrenal from its four different layers including the medulla outer cortex, innermost cortex and the middle cortex which is secreted in the glucocorticoid mineralocorticoids and the adrenal androgen and the epinephrine and norepinephrine secreted by the medulla dictates a plethora of activities all over your body starting from regulating your body under stress extreme stress regulating your water mobilization in the body by regulating the absorbing the ions and water in the discolour tubules of the kidney and to a totally diverse area from this regulating the sexual behavior. So, and on top of that the epinephrine and norepinephrine as a dual function in terms of they are involved in the heart rate increasing the heart rate and the lipolices process they increase the myocardial myocardial rate contraction rate. So, you see I mean it is covering a very very wide range small organ sitting on top of kidney plays a very critical role and this is what I wish you people to appreciate that this whole system this whole neuro endocrine axis along with as we will proceed further as we will be talking about the immune system is a very very interesting loop where things are happening in a very well controlled manner and with this I will close on this lecture and I will request you people to go through some of the nice pictures which are given online in terms of the neuro endocrine axis that will give you a better feel about it and I expect you people to go through some of the endocrine disruptors or pesticide residues or insecticide residues which does very which are fairly damaging to our endocrine system that will help you to appreciate what we eat and where we should be careful enough thanks a lot.