Renal physiology
How the kidney filters blood: the Starling forces that drive glomerular filtration, how the afferent and efferent arterioles set GFR, renal plasma flow and filtration fraction, and how inulin, creatinine and PAH clearance measure them.
5:25GFR and Starling forces at the glomerulus
Three pressures across the capillary wall set the net filtration pressure, and GFR is Kf times that number. Use them to predict why a kidney stone lowers filtration.
5:16Afferent vs efferent arteriole: GFR, RPF and filtration fraction
Two resistors set the pressure in the glomerulus. Learn the 2×2 table of afferent and efferent constriction and dilation, and use it to explain NSAID and ACE inhibitor kidney injury.
5:20Renal clearance: inulin, creatinine and PAH
Renal clearance is a bookkeeping volume, not a real flow. Use the same equation to estimate GFR with inulin and creatinine, effective renal plasma flow with PAH, and to read what the tubule did.
4:55Glucose transport maximum, splay and SGLT2
Glucosuria is not a leak in a healthy pipe. It appears when the filtered load exceeds a finite carrier capacity, the glucose transport maximum, and splay makes it start earlier than the simple threshold predicts.
5:02Countercurrent multiplier: how the kidney concentrates urine
No pump in the kidney moves water, yet urine can be several times as concentrated as plasma. The countercurrent multiplier, urea recycling and vasa recta build the medullary gradient that ADH lets the duct use.
5:20Aldosterone and ADH in the distal nephron
Two hormones act on the same stretch of tubule but do different jobs. Aldosterone moves sodium in and potassium and hydrogen out; ADH only opens water channels.
5:53Diuretics by nephron segment: loop, thiazide and more
Each diuretic class blocks one transporter in one nephron segment, and that transporter predicts the whole lab pattern. Map the four stops, then split loops from thiazides on calcium.
5:23RAAS explained: renin, angiotensin II and aldosterone
The renin–angiotensin–aldosterone system explained step by step: three triggers for renin release, four jobs for angiotensin II, and what aldosterone does in the collecting duct.