 Synthesis of adrenal steroid hormones occurs in three layers of the adrenal cortex. From outermost to inner side, these layers are zona glomerulosa, zona fasciculata, and zona reticularis, that is GFR. Zona glomerulosa synthesizes mineralocorticoids, zona fasciculata synthesizes mainly glucocorticoids, and zona reticularis synthesizes androgens. So I remember it like obviously for the layers as GFR and G synthesizes M, that is a general manager like that. So glomerulosa synthesizes mineralocorticoids. And last one I remember as Ra, like sun god Ra is there, so reticularis synthesizes androgens. So obviously the middle layer fasciculata synthesizes mostly the glucocorticoids. So what are the steps in the synthesis of these adrenal steroid hormones? Well all the steroid hormones, let it be adrenal or any other hormones like testosterone, vitamin D, all are synthesized from cholesterol. But the further steps vary. Various adrenal steroids are synthesized by multiple steps and multiple pathways. The basic one of which is this, that is cholesterol is converted to pregnenonon, which is converted to progesterone. Then there is 11-deoxy corticosterone, and then corticosterone, so this is sorry corticosterone. And finally it is converted to aldosterone. So we can remember it like pre-pro-d-c. So once you remember these steps pre-pro-d-c you will see that the other steps are also easy to remember. So if you focus here basically this pathway is synthesizing the mineralocorticoid that is aldosterone. From this pathway there are diversions also. The pregnenonon is converted to 17-hydroxy-pregnenonon and progesterone can also be converted to 17-hydroxy-progesterone. You see I have drawn two arrows from here, further there are no arrows. So when the enzyme 17-alpha hydroxylase acts on pregnenonon it creates 17-hydroxy-pregnenonon. Similarly for creating 17-hydroxy-progesterone same enzyme acts, 17-alpha hydroxylase. Now with the second pathway you see the cortisol is being synthesized which is a glucocorticoid. So again if you see it is easy to remember with the same pre-pro-d-c. It is here only difference is 17-hydroxy then it is pre-pro-d-c. So instead of corticosterone here it becomes deoxy cortisol and then cortisol. Now this pathway further again branches. So you see this 17-hydroxy-pregnenon is converted to dehydroepi-androgesterone and the 17-hydroxy-progesterone is converted to andro-stenedion. And there is a vertical pathway also DHEA is also converted to andro-stenedion. So this horizontal pathway you see same enzymes are acting 17-20 liase. So here it is 17-alpha hydroxylase and in the second step there is 17-20 liase. So horizontally we are seeing that how the various chemicals are travelling. Now vertically let us see what are the various enzymes. See for conversion of first step that is pregnenon to progesterone or 17-hydroxy-pregnenon to 17-hydroxy-progesterone or for DHEA to convert into andro-stenedion. There is same enzyme that is 3-beta hydroxy steroid dehydrogenase. Same enzyme is acting across all the steps. So you see till the top two steps the chemicals are travelling horizontally also that is they can synthesize aldosterone, cortisol or the androgens and same enzyme is acting vertically in all the three steps of adrenal steroid synthesis. Now further down if we see if you remember the steps that is pre-pro DC and here also pre-pro DC. So logically here one enzyme should act which should be common in both the zones and here also one enzyme should act which should be common in both the zones. So that is what is happening. For conversion of progesterone to 11-deoxychoticosterone or for conversion of 17-hydroxy-progesterone to 11-deoxychotisol there is enzyme 21-beta hydroxylase. Then for next step there is another enzyme that is 11-beta hydroxylase. So as I told in the beginning that glucocorticoids are synthesized in the zona fasciculata. Now if you see till here all the steps which are occurring in the synthesis of the mineralocorticoids the enzymes which are required they are also present in the zona fasciculata that means this particular pathway is also going on in zona fasciculata if cholesterol is present since enzymes are there it will form corticosterone also and cortisol also. So yes these are the major glucocorticoids which are synthesized in the zona fasciculata that is cortisol and corticosterone. The corticosterone is responsible for only 4% of the glucocorticoid activity still. These are the major steroids synthesized in zona fasciculata. Now the next step from corticosterone to aldosterone requires an enzyme aldosterone synthase which is present only in zona glomerulosa that is the reason that mineralocorticoids are synthesized only in the zona glomerulosa. So friends hopefully you have understood the steps in the synthesis of the steroid hormones I have tried to make it as easy as possible by telling you the major enzymes that is horizontally if we see it is 17 alpha hydroxylase and then 17 20 liase which are responsible for the first two steps then vertically if we see there are three major enzymes three beta hydroxy steroid dehydrogenase 21 beta hydroxylase and 11 beta hydroxylase and for the synthesis of aldosterone aldosterone synthase is required which is present in the zona glomerulosa. Now this knowledge is very important for understanding adrenogenital syndromes which will be dealing in a subsequent video. Well thanks for watching the video. 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