quiz 3 toxicology

What is the primary function of the kidneys?

To filter blood and produce urine.

What are the three main regions of the kidneys?

Cortex, Medulla, and Papilla.

What percentage of renal blood flow irrigates the cortex?

Approximately 90%.

What percentage of renal blood flow irrigates the medulla?

Approximately 6-10%.

What percentage of renal blood flow irrigates the papilla?

Approximately 1-2%.

Which nephrotoxic agent binds sulfhydryl groups of proteins?

Mercury.

How do NSAIDs affect renal function?

They inhibit COX-1, reduce prostaglandin synthesis, and cause renal vasoconstriction.

What is the role of the glomerulus in the kidneys?

It fractionates blood into a virtually protein-free and cell-free ultrafiltrate.

What is reabsorbed in the proximal tubule?

60-80% of solute and water, including Na+, K+, HCO3−, Cl−, PO4^3−, Ca2+, Mg2+, amino acids, glucose, and low-molecular-weight proteins.

What is the primary function of the Loop of Henle?

To reabsorb filtered Na, Cl, and water.

What happens in the early distal tubule?

It reabsorbs most remaining Na+, K+, and Cl− but is relatively impermeable to water.

What critical roles do the collecting ducts play?

Secretion of H+ and reabsorption of HCO3− regulate blood pH.

What triggers afferent arteriolar constriction in the kidneys?

Increased solute concentration at the macula densa.

What is acute kidney injury?

A sudden decline in glomerular filtration rate.

What are prerenal factors that can cause acute kidney injury?

Renal vasoconstriction, intravascular volume depletion, and insufficient cardiac output.

What are intrarenal factors that can cause acute kidney injury?

Tubular cell injury, interstitial nephritis, and ureteral or bladder obstruction.

What is a notable cellular adaptation response of the kidneys?

Metallothionein induction and stress protein induction.

Why are the kidneys particularly susceptible to toxicity?

They receive 20-25% of resting cardiac output and can concentrate toxicants in tubular fluid.

What effect do nephrotoxicants have on glomerular permeability?

They can alter glomerular permeability to proteins.

What are some examples of nephrotoxicants that impair glomerular ultrafiltration?

Cyclosporine, amphotericin B, and gentamicin.

What role do heavy metals play in glomerular injury?

They may function as haptens, binding to proteins and attracting inflammatory cells.

What is the consequence of damage to renal tubules?

Detachment and death of epithelial cells, leading to tubular obstruction.

What is the compensatory response of the kidney after unilateral nephrectomy?

GFR of the remnant kidney increases by approximately 40-60%.

What is the significance of the macula densa in kidney function?

It regulates glomerular filtration rate (GFR) based on solute concentration.

What is the most common site of toxicant-induced renal injury?

The proximal tubule.

What percentage of solute and water is reabsorbed at the proximal tubule?

~ 60 - 80%.

What are OATs and OCTs in relation to the proximal tubule?

They are transporters that selectively concentrate some toxicants in the epithelial cells of the proximal tubules.

What activities are highest in the proximal tubule?

Cytochrome P450 and cysteine conjugate β-lyase activities.

What can reductions in renal blood flow cause in the papilla?

Ischemia and tissue damage.

What initial assessments are used to evaluate nephrotoxicity?

Evaluating serum and urine chemistries.

What does an increase in blood urea nitrogen (BUN) indicate?

It is an indirect marker of glomerular filtration rate (GFR).

What does glucosuria suggest?

Defects in proximal tubular reabsorption or secondary to hyperglycemia.

What does albuminuria indicate?

Suggestive of glomerular damage.

What historical event highlighted cadmium poisoning?

The outbreak of Itai-itai disease in Japan in 1954.

What are the main anthropogenic sources of cadmium?

Mining, smelting, coal combustion, and burning of municipal waste.

How does cadmium accumulate in plants?

Uptake occurs via roots and accumulates in leaves, stems, and grains.

What is the half-life of cadmium in human kidneys?

10-20 years.

What is the primary target organ for cadmium accumulation?

The liver, kidneys, and bones.

What role do metallothioneins (MT) play in cadmium exposure?

They perform detoxifying and regulatory roles in the body.

How does cadmium disrupt calcium homeostasis?

Cd²⁺ mimics Ca²⁺ and competes for uptake via Ca²⁺ channels.

What effect does cadmium have on vitamin D activation?

It inhibits the 1α-hydroxylase enzyme, reducing calcitriol production.

What are some specific nephrotoxicants mentioned?

Cadmium, non-steroidal anti-inflammatory drugs (NSAIDs), and ethylene glycol.