NEPHRON — DRAWABLE EXAM DIAGRAM
Reproduce this U-shape in 2 min. Label segments + pin drugs/diseases/hormones.
GLOMERULUS
Bowman's capsule
Afferent
PG dilates / NSAID constricts
Efferent
Ang II constricts
ACEi/ARB dilate → renoprotect
Cr ≤30% rise = keep. >30% = stop.
PCT "Bulk Worker"
65% Na⁺, ALL glucose
ALL HCO₃⁻ (CA-II)
ALL amino acids, 85% PO₄
90% uric acid (URAT1)
💊 SGLT2i (Dapa/Empa)
💊 Acetazolamide
⚡ RTA Type 2 (HCO₃⁻ waste)
⚡ Fanconi (global PCT fail)
SGLT2i → ↓urate (uricosuric)
Euglycemic DKA = the trap
→ MetAcidosis, HypoK⁺, HypoPO₄
LOH "Concentration Engine"
25% Na⁺ via NKCC2
(Na⁺/K⁺/2Cl⁻ cotransporter)
Paracellular Ca²⁺, Mg²⁺
💊 Furosemide (blocks NKCC2)
⚡ Bartter = genetic furosemide
→ HypoK⁺, MetAlk, HypoCa²⁺
→ HypoMg²⁺, ↑Uric acid
Bartter=Big,Baby,Big loop
DCT "Fine Tuner"
5% Na⁺ via NCC (Na⁺/Cl⁻)
Ca²⁺ reabsorb (PTH→TRPV5)
Mg²⁺ reabsorption
💊 Thiazide (blocks NCC)
⚡ Gitelman = genetic thiazide
→ HypoK⁺, HypoNa⁺ (#1 drug)
→ ↑Uric acid, ↑Ca²⁺ (paradox)
Gitelman=Gentle,low maGnesium
CD "Final Decision — 2 MASTERS"
MASTER 1: ALDOSTERONE
Source: Zona glomerulosa (adrenal)
Stimulus: Ang II + HyperK⁺ + ACTH
→ MR receptor → ENaC (Na⁺ in)
+ ROMK (K⁺ out) + H⁺-ATPase
💊 Spironolactone (MR block)
⚡ Conn's = excess → HypoK⁺+HTN
⚡ RTA4 = deficient → HYPERK⁺
RTA4 = DM#1 + ACEi. Commonest RTA.
MASTER 2: AVP/ADH (Vasopressin)
Source: Supraoptic nucleus → post.pit
Trigger: ↑Osm>285 / ↓Volume / AngII
→ V2 receptor → cAMP → AQP2 insert
V1a=vasoconstrict V1b=ACTH
💊 Desmopressin (V2 agonist→centralDI)
💊 Tolvaptan (V2 antagonist→SIADH)
⚡ SIADH=excess→dilutional HypoNa⁺
⚡ CentralDI=no AVP (desmo works)
⚡ NephroDI=V2 resist (desmo fails)
Lithium=#1 drug cause nephroDI
α-Intercalated: H⁺ secretion (H⁺-ATPase)
⚡ RTA1 = failure → pH>5.5 + HypoK⁺ + stones
ALDO→
AVP→
RAAS CASCADE
↓Perfusion → RENIN
→ Ang I → [ACE] → Ang II
→ Aldosterone → CD
X ACEi at ACE step
X ARB at AT1 receptor
X Sacubitril at neprilysin
(neprilysin degrades ANP/BNP)
URIC ACID
SGLT2i → ↓urate (PCT)
Thiazide → ↑urate (DCT)
Furosemide → ↑urate (vol)
Losartan → ↓urate (URAT1)
Low-dose ASA → ↑urate
→ URINE