CARDIO - RESPIRATORY - RENAL INTEGRATED TRANSFER
YEAR 2 | PAGE 47D - CROSS-SYSTEM HOMEOSTASIS + 10 HIGH-DISCRIMINATION CASES
INTEGRATION RULE: HEART SETS FLOW/PRESSURE, LUNGS SET VENTILATION/OXYGENATION/CO2, KIDNEYS SET VOLUME/ELECTROLYTES/HCO3-. A SYSTEMS QUESTION OFTEN STARTS IN ONE ORGAN AND IS SOLVED BY THE COMPENSATION OR CONSEQUENCE IN ANOTHER. J. CROSS-SYSTEM INTEGRATION MAP
| LANE | MUST RETRIEVE WITHOUT NOTES | HIGH-DISCRIMINATION TRANSFER |
|---|---|---|
| Shock / perfusion | Hemodynamics + baroreflex + RAAS/ADH + renal perfusion + lactate/acid-base. | Identify the primary hemodynamic defect, then predict kidney/acid-base compensation and tissue consequence. |
| Heart failure / edema | Pump failure -> venous pressure/congestion -> RAAS/ADH -> Na/H2O retention -> pulmonary/systemic edema. | Separate effective arterial volume from total-body volume; explain why edema and renal Na retention coexist. |
| Pulmonary disease / acid-base | Ventilation sets PaCO2; kidneys alter HCO3-/H+ over time. | Distinguish acute vs chronic respiratory disturbance and whether renal compensation is appropriate. |
| PE / right heart / kidney | Dead-space/VQ defect + acute RV afterload -> reduced LV preload/CO -> renal hypoperfusion when severe. | Connect dyspnea/hypoxemia to pulmonary vascular obstruction and hemodynamic consequences. |
| Diuretics / lungs / heart | Changing renal Na/water handling changes preload and congestion while also altering K/H+/Mg/Ca. | Predict both the desired hemodynamic effect and the expected electrolyte/acid-base toxicity. |
K. 10 HIGH-DISCRIMINATION INTEGRATED CASES
| # | CASE | ANSWER LOGIC |
|---|---|---|
| 1 | Loop shows higher ESV after acute pressure load. | Afterload increased: ventricle ejects less -> ESV rises; do not call this reduced preload. |
| 2 | Systolic murmur gets louder with lower LV volume. | Think dynamic obstruction/MVP physiology; use chamber/loading logic before memorized maneuvers. |
| 3 | Dyspnea + low O2, high A-a gradient, poor response to O2. | True shunt becomes more likely than simple hypoventilation or low V/Q. |
| 4 | FEV1/FVC low with hyperinflation. | Obstructive physiology: flow problem first; then distinguish asthma/COPD from reversibility/history. |
| 5 | Normal ratio but TLC and DLCO low. | Restrictive parenchymal process is favored over pure chest-wall/neuromuscular restriction. |
| 6 | ACE inhibitor started in bilateral renal-artery stenosis; creatinine rises. | Efferent dilation lowers glomerular pressure/GFR in a kidney dependent on angiotensin-II-mediated efferent tone. |
| 7 | Loop diuretic causes hypokalemic metabolic alkalosis. | Segment effect -> increased distal Na delivery + volume contraction/aldosterone -> K/H+ loss. |
| 8 | AKI with muddy brown casts after shock. | Localize to tubular injury after ischemia; sediment beats vague BUN/Cr pattern memorization. |
| 9 | COPD with chronic hypercapnia has elevated HCO3-. | Kidneys retain bicarbonate over time: appropriate chronic respiratory-acidosis compensation. |
| 10 | Decompensated HF has edema yet RAAS is activated. | Effective arterial volume is low despite high total-body fluid; renal response follows perceived perfusion, not edema appearance. |
L. OFFICIAL PRACTICE + READINESS STACK
| RESOURCE | ROLE IN THIS REVIEW |
|---|---|
| USMLE Step 1 content specifications | Defines official scope; use the current version before testing. |
| NBOME COMLEX-USA Level 1 | DO-specific official exam information and current blueprint links. |
| UWorld Step 1 | Primary vignette-transfer layer when used deeply. |
| AMBOSS USMLE | Targeted repair + mixed questions after a defined weakness. |
| NBME CBSSA | External-style formative calibration; interpret with school policy and multiple signals. |
| TrueLearn | COMLEX-formatted transfer option for DO learners. |
L. OFFICIAL PRACTICE + READINESS STACK — M. THREE-SYSTEM MASTERY GATE
Ready to move on when you can: (1) reconstruct the normal cardio/pulmonary/renal model without notes; (2) identify the primary physiologic failure before naming the disease; (3) interpret an unfamiliar ECG/PV loop/PFT/ABG/urinalysis/clearance problem; (4) predict cross-system compensation; (5) connect the mechanism to the relevant pathology, diagnostic inference and drug target; and (6) show that repeated misses are shrinking on new mixed questions. This is an educational review framework, not a substitute for school requirements, faculty supervision, official exam guidance or clinical decision-making. 2026/27 systems-review expanded edition - align with school objectives and verify official exam updates before testing