 growth hormone is released by acidophilic cells of pituitary. Now this growth hormone release is under the control of growth hormone releasing hormone from hypothalamus and there is another one which inhibits the release of the growth hormone that is somatostatin also known as growth hormone inhibitory hormone. So it is under dual control growth hormone releasing hormone and also growth hormone inhibitory hormone that is somatostatin. So what is the stimuli which cause the release of the growth hormone? See hypothalamus is the master integrator so there are various stimuli which can be detected at the hypothalamus and this in turn will regulate the release of the growth hormone. So major stimuli which cause the release of growth hormone releasing hormone from hypothalamus include conditions in which fuel decreases. So whenever there is decrease in blood glucose decrease in free fatty acids as in case of post-absorptive state post-absorptive so like after meal there will be a time say as opposed to three hours when there will be absorption of the nutrients that time insulin will be high. But conditions whenever there is fuel decrease one example being post absorptive state or in case of starving then in that case growth hormone releasing hormone will be released more and there will be increase in growth hormone. Another very important estimulator is conditions in which blood amino acids increase. So in that case also growth hormone releasing hormone will increase. Now remember that whenever blood amino acids increase what are those conditions? Well obviously when there is excessive protein breakdown so one important condition is here known as protein depletion. So chronic starvation suppose there is protein depletion. On the other hand if the person is on high protein diet in high protein diet also this protein will be breakdown and there will be absorption of lot of amino acids in blood. So on one hand cellular protein depletion and also in case of high protein diet both cases there will be increase in growth hormone releasing hormone. Then any kind of stress exercise trauma that will also increase the release why? Again you see these conditions if you refer there will be protein breakdown. Okay protein breakdown stress and trauma and that will cause increase in growth hormone release and in case of exercise what happens that there is an acute condition of fuel depletion. So in that case again as I told you whenever fuel is depleted there will be increase in the growth hormone. So this concept you have to remember fuel depletion so that will include decreased blood glucose decreased free fatty acid and cellular protein depletion and increase in amino acids in blood. So if you remember this increase in amino acids you see protein depletion because there is protein breakdown then also there will be increase in the amino acids so that will be easy to remember. Then there are other stimuli that include hormones these hormones are testosterone, estrogen so you know in case of puberty these concentration of these hormones is high and there is growth spurt also at the time of puberty. Why is there a growth spurt? Because of the release of growth hormone by the stimuli which is coming due to these hormones. Then there is another hormone ghrelin which is released from stomach. Simple to remember see the full form of ghrelin I break it down like gh growth hormone re releasing hormone. Okay so growth hormone releasing hormone ghrelin causes release of the growth hormone. Then growth hormone is also released in first two hours of deep sleep that is NREM sleep. Okay so you remember that our grandmothers used to say that children grow during sleep and that should be actually deep sleep. Okay so first two hours of deep sleep NREM releases. On the other hand REM sleep actually inhibits inhibits the release of the growth hormone. So these are the major stimuli which cause the release of the growth hormone but there is a feedback regulation also and what is this feedback regulation? See growth hormone releasing hormone acts on pituitary and causes the release of growth hormone from the pituitary. Okay now this growth hormone acts on liver and causes release of insulin like growth factor one. So this is known as pituitary liver axis. Okay hypothalamic pituitary liver axis. So obviously here growth hormone is the fundamental hormone which is going to have its effect but it also causes release of IJF1 which also has certain effects and this IJF1 you see it is a negative feedback regulator. IJF1 in turn causes inhibition of the release of the growth hormone and it causes stimulation of the release of somatostatin and somatostatin is an inhibitory hormone it inhibits the release of the growth hormone. So IJF1 is acting at the level of pituitary as well as at the level of the hypothalamus for inhibiting the release of the growth hormone. Then growth hormone itself acts on hypothalamus inhibiting the release of the growth hormone releasing hormone. So these are the major stimuli for the release of the growth hormone and there is negative feedback regulation as well. Let us move on to actions of growth hormone. One thing you remember that whenever we talk about any hormone you should remember its principal function. Once you remember its principal function it will be very easy to remember its actions. Okay so principal function of the growth hormone as the name indicates is to cause the growth of anything which can grow. Okay so that is the principal function and for growth what is required nutrients are required. Okay so growth hormone makes this nutrients available and obviously there will be multiplication of the cells differentiation of the cells that also is caused by growth hormone. So two levels are there one is making the nutrients available and then causing the growth per se. So how does the growth hormone make the nutrients available that is by its action on various metabolic cycles. Okay so it affects the metabolism of all three that is carbohydrates, fats and proteins and as I told you that its basic function is to make the nutrients available. Okay so what it will do to carbohydrate is that there will be increase in gluconeogenesis so that more glucose is available. Okay increase in gluconeogenesis but it decreases the peripheral utilization of glucose we will come to it why it is happening it decreases the peripheral utilization of glucose basically by muscle. Then in the fats it promotes lipolysis so there will be increased lipolysis in where lipolysis occurs in adipose tissue. Okay and there will be decrease in lipogenesis and proteins what it should do to proteins see it has to cause growth and for growth proteins are very important the amino acid should not be used as fuel rather they should be used for increasing the mass of the cells so there is actually protein synthesis so growth hormone promotes protein synthesis. Okay not protein catabolism protein catabolism is decreased so that is growth hormone acting as protein sphere okay very important. So even though it is making the nutrients available for fuel but for proteins it is acting as protein sphere. So how does it bring about this increase in protein synthesis that is the actions of the growth hormone it increases the amino acid entry into the cells because these amino acids once they enter into cells then only they can be used for protein synthesis so increase amino acid entry into the cells increased RNA translation so RNA translation is basically conversion of RNA to proteins and the increased DNA transcription meaning again conversion of DNA formation of RNA basically from DNA so it increases all these three aspects to increase the protein synthesis. Now I told you that I will talk about this decreased peripheral utilization of glucose see glucose is a substance which is basically used by brain okay so carbohydrates even though it increased gluconeogenesis it decreases peripheral utilization of glucose so that whatever glucose is there it can be used by neurons. On the other hand it is also causing lipolysis so fats can be easily used as fuel understanding so basically this growth hormone is having anti-insulin action it is increasing the insulin resistance important also because this time we want the fuel to be available and not to be stored okay so these are the basic fundamental actions on metabolism. What are the actions on growth so I told you that it causes growth of anything which can grow right but the best effect is on bone and muscles okay and how will it be possible in bone how will the bone grow we want the more deposition of the cartilage right so the chondrocytes deposit more protein at the end of the bones then there is increased reproduction increased multiplication also of these cells then chondrocytes are also converted to osteogenic cells so that there will be increased deposition of the bone on the cartilage which has been deposited so osteoblasts osteoblasts cells are very strongly stimulated by growth hormones so that is the action on bone what about the muscle there will be muscle hypertrophy muscle hypertrophy because as I told you that it is causing increase in the protein synthesis so muscle hypertrophy will also affect and for all these things for the growth you see they should be a positive balance of calcium right phosphorus because these are required for synthesis of minerals in bones so they should increase they should not be lost in urine right so there is a positive balance of calcium phosphorus magnesium also so gastrointestinal absorption of calcium is increased and its excretion is decreased and why is it so see the requirement is increased isn't it so these minerals are diverted for growth rather than being lost in urine now before I told you that growth has two actions one on metabolism and on multiplication and it acts via two ways one directly by the growth hormone acts and the other is via release of the insulin line growth factor which is also known as somatomidin from liver so which of these actions is caused by growth hormones and which of these actions is caused by IGF well in simple terms you remember that the actions on metabolism are by growth hormone directly and the actions for growth are by insulin like growth factor one okay simple to remember so direct action that is by the growth hormone itself that is known as direct actions that is on metabolism and indirect actions that is via release of IGF fund are on growth but only one thing you remember that this protein synthesis it is a quite for growth we are telling so protein synthesis is by growth hormone as well and by IGF one as well okay so those are the actions of growth hormone now based on these actions let us see what are the abnormalities which can occur with the deficiency or excess of release of growth hormone so abnormalities can be either due to deficiency and the other one can be is due to the excess we are telling that growth hormone is causing growth so deficiency of growth hormone in childhood in childhood it causes dwarfism so that is the abnormality which occur if for deficiency occurs in childhood but there are certain characteristics of this dwarfism that in dwarfism caused by decreasing the growth hormone all parts of body develop in proportion to each other so everything will be small understanding so very important that all parts of body develop in proportion to each other this is in contrast to dwarfism which is caused by maybe thyroid hormone deficiency in children because in them soft tissue enlargement occurs soft tissue grows much more than the bony part so in growth hormone deficiency all body parts develop in proportion to each other and if all the other hormones which are released from pituitary that is there is a gonadotropin that is LH and FSH if these are normal then the sexual function will also be normal PSH is normal then the thyroid hormone release will also be normal so everything else is normal except the person is dwarf however in case of pan hypopiturism when there is deficiency of all the hormones which are released from the pituitary in that case we will see that the person is lethargic also because of the presence of hypothyroidism and sexual function will also be abnormal so that is dwarfism there is one special type of dwarfism in which growth hormone actually is normal or can be increased also when can it occur I told you before that IGF1 is responsible for the growth so if growth hormone is not able to acts on its receptor and cannot produce IGF1 then that causes the this kind of dwarf where growth hormone will be normal why it can be increased because IGF1 is not there so we saw that IGF1 is causing a negative feedback inhibition right so that negative feedback inhibition is gone and growth hormone is increased so this kind of dwarfism the name given is levy lauren dwarf levy lauren dwarf so that was deficiency in children what about deficiency of the growth hormone in adults will there be any problem the growth has already occurred but the person may suffer from hypoglycemia because growth hormone is very important hormone which are which is released in case of post absorptive state and maintains the fuel so adults will suffer from episodes of hypoglycemia let's come to the excess growth hormone what will happen so in deficiency we saw in children and in adults in excess growth hormone we will see as before puberty okay that is before closure of the epiphyzes and after puberty that is after closure of the epiphyzes now same thing if you know the actions just exaggerate all the actions and you will know what will be the problems so if it is before puberty what is the main action of growth hormone it is causing excessive growth so there will be excessive growth of everything there will be excessive growth of the bone of other organs as well so there will be tall height right excessively tall and there will be organomegaly also very important okay especially damaging is the organomegaly of the kidneys so tall height organomegaly then there is soft tissue enlargement also will occur soft tissue enlargement will cause large hands and feet then due to its action on metabolism there will be hyperglycemia hyperglycemia because it is action is anti-insulin it is increasing the insulin resistance so this is kind of a diabetic condition and you see whenever there is hyperglycemia there is increase in insulin resistance right so this hyperglycemia will stimulate the release of the insulin and with time more and more insulin is being released and what will happen ultimately beta cell exhaustion will occur the beta cells will stop producing any more insulin and this will lead to frank diabetes mellitus which will need actually the insulin injections for the patient so initially it is started as a hyperglycemia caused due to excess of growth hormone but later on this can lead to frank diabetes mellitus fine what about excess growth hormone after puberty if it is after puberty remember that the closure of epipyzes has already occurred okay it is over so now the bone growth cannot occur rather other tissues can still enlarge right so what we will see is there will be soft tissue enlargement so there will be large hands feeds ears will be large nose will be large okay lips will be large then the membranous bones can actually grow so the flat bones of the skull which are there they will grow so there will be protrusion of the jaw will be protruded okay forehead will be protruded so membranous bones can grow remember that right so soft tissue enlargement and the expansion of the skull will be there then because of this soft tissue enlargement what we see that compression of the structures nerve structures can occur so there will be presence of carpal tunnel syndrome compression of the nerve can occur at wrist joint then this membrane is more than I was talking about the expansion of the skull then vertebra also comes in these and vertebral expansion can lead to kyphosis and again the compression of the nerve scan occur then many other features because of this soft tissue enlargement are seen vocal cords thicken resulting in thick deep voice then coming to metabolic abnormalities what can be the metabolic abnormalities again there will be diabetes okay diabetes will be seen then same it causes lipolysis also right so that means fats is used as fuel and excessive fats will lead to generation of ketone bodies so ketone bodies will increase and there will be ketosis can occur then because of excessive fat mobilization from adipose tissue there will be fatty liver as well okay so remember so when we are talking about excess think about the growth abnormalities which can occur so before puberty height will increase organoma galley soft tissue enlargement will occur after puberty height will not increase however organoma galley and soft tissue enlargement can occur and when we are talking about metabolic abnormalities they will be same in both before puberty after puberty okay and how to treat this gigantism which is basically the abnormality which is occurring before puberty so this is gigantism and this occurring after puberty acromegaly as I told you that will be enlargement of the hands and feet so acro is used for that the megal is enlargement so what will be the treatment of gigantism and acromegaly we can use somatosatin analog so we have seen in the regulation of release that somatosatin causes decrease in the release of the growth hormone so somatosatin analogs can be used then growth hormone receptor antagonist can be used so that even if growth hormone is there it is not able to act growth hormone receptor antagonist can be used and if the condition is due to a pituitary tumor acidophilic cells tumor acidophilic cells are the cells which are releasing growth hormone right then surgery has to be done so surgical removal of the pituitary tumor can be done so that was the fundamentals and concepts in growth hormone I hope the mechanism I told you how to remember the actions of any hormone just remember the principal action and think about the logic and then try to see whether it is fitting in your logic the actions which are there so with that you will never forget the actions of the growth hormone thank you for watching the video if you liked it do press the like 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