First modification to cholesterol & where

Converted to the steroid pregenolone by cleaving 6C side chain using cytochrome P450 leaving a ketone group. This is in the adrenal cortex mitochondrial inner membrane

Converted into 3 classes by smooth ER to progesterone: further sex steroids), mineralocorticoids, & glucocorticoids

Progesterone → androgens

Pregenolone 3-OH to 3=O is progesterone, is hydroxylated & cleaved to androstenedione which can make estrone (weaker than oestrogen) & reduced to testosterone. A-ring is aromatised & reduced to oestrogen

mineralocorticoids (& vitamin D3)

Aldesterone which regulates water & salt. 7-dehydrocholestrol in the skin has its B-ring cleaved by UV light to form provitamin-D which spontaneously rearranges into cholcalciferol

Ionized salts at physiological pH, detergent that solubilises lipids

Intoxication liver cholestasis

Inhibition of canalicular bile salt export pumps causes high intracellular concentrations. This solubilises hepatocyte cell membranes & membrane-bound organelles

Bile acids as signalling molecules

Can bind to nuclear FXR receptors to suppress bile synthesis, increase lipid & glucose metabolism, increase energy expenditure, & create a feedback loop to prevent toxicity

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Bile salts

Uni of Notts, Signalling & Metabolic Regulation, Year 2, Topic 14

Term	Definition
First modification to cholesterol & where	Converted to the steroid pregenolone by cleaving 6C side chain using cytochrome P450 leaving a ketone group. This is in the adrenal cortex mitochondrial inner membrane
Fate of pregenolone	Converted into 3 classes by smooth ER to progesterone: further sex steroids), mineralocorticoids, & glucocorticoids
Progesterone → androgens	Pregenolone 3-OH to 3=O is progesterone, is hydroxylated & cleaved to androstenedione which can make estrone (weaker than oestrogen) & reduced to testosterone. A-ring is aromatised & reduced to oestrogen
mineralocorticoids (& vitamin D3)	Aldesterone which regulates water & salt. 7-dehydrocholestrol in the skin has its B-ring cleaved by UV light to form provitamin-D which spontaneously rearranges into cholcalciferol
Bile acids/salts	Ionized salts at physiological pH, detergent that solubilises lipids
Intoxication liver cholestasis	Inhibition of canalicular bile salt export pumps causes high intracellular concentrations. This solubilises hepatocyte cell membranes & membrane-bound organelles
Bile acids as signalling molecules	Can bind to nuclear FXR receptors to suppress bile synthesis, increase lipid & glucose metabolism, increase energy expenditure, & create a feedback loop to prevent toxicity

Created by: Denny12

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