USMLE Renal 4 Nephron Pharmacology

>> YOUR LINK HERE: ___ http://youtube.com/watch?v=gG7ROLrmPCs

Want to support the channel? Be a patron at: • / lymed Welcome to LY Med, where I go over everything you need to know for the USMLE STEP 1, with new videos every day. • Follow along with First Aid, or with my notes which can be found here: https://www.dropbox.com/sh/mt1jrikc24... • In our last video, we discussed anatomy and physiology of the nephron, now let's talk about some pharmacology! Pharm and drugs that target our kidneys are commonly prescribed and often are used to help us lose excess fluid. Hence they are called diuretics. We'll break it up systematically, by looking at what drugs target what particular area of the nephron. So we first look at the normal pathway and then the drugs. • Proximal convoluted tubule (PCT): acetazolamide works here by blocking carbonic anhydrase. This stops the Na/H pump and therefore you can't reabsorb sodium and bicarb. This reduces bicarb rich fluid, like in your eye (glaucoma) or csf (reduce raised ICP). Other situations reduce alkalosis like in altitude sickness and in metabolic alkalosis. Another drug is mannitol, which is a non-absorbable sugar which osmotically draws fluid. Know that it can exacerbate anuria, pulmonary edema, and heart failure. • Loop of Henle: loop diuretics like furosemide block the massive Na/K/Cl channel in the thick ascending limb. This is our most powerful diuretic. Side effects include ototoxicity, nephritis, dehydration, gout, and contraction alkalosis. • Distal convoluted channel: blocked by thiazide diuretics which increase the reabsorption of calcium. Side effects is hyperglycemia, hyperlipidemia, hyperuricemia and hypercalcemia. • Collecting duct: these are called potassium sparing diuretics (K+ sparing diuretics). These either work on aldosterone or on our ENAC channels. Thus they decrease the channel as either blocking ENAC or acting as competitive aldosterone receptor antagonists. Side effects: spironolactone is structurally similar to androgens and can lead to gynecomastia, erectile dysfunction, and impotence.

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