M13 TOXI LEC FINALS

Which intrinsic renal structure receives the highest volumetric blood flow relative to its mass, and what is the physiological consequence of this with regard to toxicant exposure?

• Renal papilla; higher toxin exposure due to concentrated tubular fluid

• Renal cortex; more exposure to circulating blood-borne toxicants due to high perfusion

• Medulla; increased vulnerability due to sluggish blood flow

• Pelvis; accumulation of toxins in the urine

The glomerular filtration rate (GFR) depends on the filtration coefficient (Kf) and net filtration pressure. Which toxicant-induced alteration would most directly reduce Kf?

• Renal artery vasoconstriction

• Podocyte injury reducing filtration surface area

• Increased efferent arteriole resistance increasing hydrostatic pressure

• Tubuloglomerular feedback increasing renin release

In ischemic acute kidney injury (AKI), which segment of the nephron is most susceptible to hypoxic injury and why?

• Distal convoluted tubule due to low blood flow

• Medullary thick ascending limb due to high metabolic demand and low oxygen tension

• Glomerulus due to direct toxin filtration

• Collecting duct due to ADH-mediated water reabsorption

Which pathophysiologic mechanism best explains decreased GFR in NSAID-induced AKI?

• NSAID-induced systemic hypotension decreasing renal perfusion

• Inhibition of cyclooxygenase-mediated vasodilatory prostaglandins leading to afferent arteriole vasoconstriction

• Direct tubular cytotoxicity reducing filtration membrane permeability

• Increased activation of renin-angiotensin-aldosterone system (RAAS) leading to efferent arteriole dilation

Cyclosporine nephrotoxicity involves vasoconstriction. Which mediator plays a pivotal role in this process?

• Prostacyclin (PGI2)

• Endothelin-1

• Nitric oxide

• Bradykinin

Which of the following best describes the molecular triggering event in acetaminophen nephrotoxicity?

• Direct alkylation of mitochondrial DNA by para-aminophenol (PAP) metabolite

• Renal cytochrome P450 2E1-mediated formation of a reactive quinone-imine intermediate covalently binding proximal tubular proteins

• Immunologically mediated renal interstitial inflammation

• Oxidative damage to the glomerular basement membrane by N-acetyl-p-benzoquinone imine (NAPQI)

The pathogenesis of analgesic nephropathy includes chronic medullary ischemia. What distinct pathological lesion characterizes this condition?

• Global glomerulosclerosis

• Papillary necrosis and chronic interstitial nephritis

• Crescentic glomerulonephritis

• Mesangial proliferative glomerulonephritis

In aminoglycoside nephrotoxicity, lysosomal rupture releases enzymes into the cytoplasm. What is the primary consequence of this event in tubular cells?

• Induction of tubular cell apoptosis via mitochondrial pathway

• Activation of complement cascade and immune response

• Initiation of necrotic cell death due to membrane disruption

• Promotion of tubular cell proliferation causing hyperplasia

Cisplatin nephrotoxicity involves multiple renal compartments. Which of the following is LEAST likely to be involved?

• Tubular necrosis

• Vascular endothelial injury

• Podocyte foot process effacement

• Interstitial fibrosis

The adaptive increase in single-nephron GFR following nephron loss is mediated primarily through:

• Increased renal arterial pressure globally

• Enhanced efferent arteriole constriction increasing glomerular capillary pressure

• Upregulation of tubular sodium reabsorption decreasing tubuloglomerular feedback

• Decreased afferent arteriole tone reducing glomerular pressure