Phys 30 Flashcards

Which compartment normally contains the highest potassium concentration?

A) Plasma water

B) Interstitial fluid

C) Intracellular fluid

D) Transcellular fluid

Too much Aldosterone leads to:

A) Hypokalemia

B) Hyperkalemia

Aldosterone deficiency leads to:

A) Hypokalemia

B) Hyperkalemia

A patient with acute lactic acidosis develops elevated serum potassium. Which mechanism best explains this acute change?

A) Increased ROMK channel insertion

B) Inhibited sodium-potassium pump

C) Enhanced type A reabsorption

D) Increased paracellular potassium leak

Which potassium pattern best matches acute metabolic acidosis?

A) Hyperkalemia

B) Chronic hypokalemia

C) Normal serum potassium

D) Pseudohyperkalemia

Which potassium pattern best matches chronic metabolic acidosis?

A) Persistent hyperkalemia

B) Chronic hypokalemia

C) Normal serum potassium

D) Pseudohyperkalemia

A sprinter collapses after maximal exertion and has a transient rise in serum potassium. Which scenario best matches this potassium disturbance?

A) Strenuous exercise causing hyperkalemia

B) Insulin surge causing hyperkalemia

C) Aldosterone excess causing hyperkalemia

D) Beta stimulation causing hyperkalemia

A patient with severe dehydration has high extracellular osmolarity and elevated serum potassium. Which shift best explains this finding?

A) Potassium shifts into cells

B) Potassium shifts from cells

C) Potassium binds plasma proteins

D) Potassium enters bone matrix

In normal renal handling, which nephron segment reabsorbs the greatest amount of filtered potassium?

A) Thick ascending limb

B) Distal convoluted tubule

C) Proximal convoluted tubule

D) Cortical collecting duct

A renal physiologist compares potassium handling across nephron segments. Besides the PCT, which segment reabsorbs significant potassium?

A) Thin descending limb

B) Thick ascending limb

C) Connecting tubule

D) Outer medullary duct

A patient with hyperkalemia is treated with measures that increase renal potassium elimination. Which cell type is most important for potassium excretion?

A) Principal cells

B) Type A intercalated cells

C) Podocytes

D) Macula densa cells

Which nephron location is most important for regulated potassium excretion into tubular fluid?

A) PCT and thin limb

B) TAL and macula densa

C) Distal and collecting tubules

D) Glomerulus and Bowman space

A researcher blocks the main apical potassium secretory channels in principal cells. Which two channels are directly inhibited?

A) ENaC and NCC

B) BK and ROMK

C) NKCC2 and NCC

D) UT-A1 and UT-A3

During high tubular flow, a potassium secretory channel in principal cells becomes especially relevant. Which channel is high-conductance and flow-sensitive?

A) ROMK channel

B) BK channel

C) ENaC channel

D) NCC channel

A patient with severe total body potassium depletion begins conserving potassium in the distal nephron. Which cell type mediates this adaptive reabsorption?

A) Principal cells

B) Podocytes

C) Type A intercalated cells

D) Macula densa cells

Severe potassium depletion activates distal potassium reabsorption through which transporter and cell type?

A) ENaC in principal cells

B) ROMK in principal cells

C) NKCC2 in thick ascending limb

D) H/K ATPase in intercalated cells

Which acid-base disturbance is classically associated with acute extracellular potassium accumulation?

A) Acute metabolic acidosis

B) Chronic metabolic acidosis

C) Metabolic alkalosis

D) Respiratory alkalosis

A patient has chronic diarrhea. Which pattern is expected?

A) Hyperkalemia from acute shifting

B) Hypokalemia from chronic acidosis

C) Hyperkalemia from beta-two activity

D) Hypokalemia from aldosterone deficiency

Aldosterone lowers serum potassium by which paired mechanisms?

A) Excretion and cellular uptake

B) Reabsorption and cellular release

C) Filtration and protein binding

D) Secretion and phosphate complexing

A patient receives high-dose loop diuretics and develops hypokalemia. Increased distal tubular flow promotes which potassium process?

A) Reabsorption

B) Complexing

C) Excretion

D) Filtration

Which set of conditions promotes potassium excretion by increasing distal tubular flow?

A) Hypovolemia, hyponatremia, Addison disease

B) Hypernatremia, diuretics, volume expansion

C) Acidosis, insulin, beta stimulation

D) Dehydration, exercise, adrenal failure

A patient with metabolic alkalosis develops paresthesias and carpopedal spasm despite normal total calcium. Which mechanism explains this tetany?

A) Less protein-bound calcium

B) More ionized calcium

C) More protein-bound calcium

D) Less phosphate-complexed calcium

Which acid-base state makes hypocalcemic tetany more likely by lowering freely ionized calcium?

A) Metabolic alkalosis

B) Metabolic acidosis

C) Respiratory acidosis

D) Normal acid-base status

Which hormone is a major regulator of renal calcium handling and calcium homeostasis?

A) Aldosterone

B) Insulin

C) PTH

D) Epinephrine

Why is only about 60% of plasma calcium filtered by the kidney?

A) It is all intracellular

B) It is all secreted

C) It is freely ionized

D) It is entirely reabsorbed

A nephron segment reabsorbs the largest fraction of filtered calcium, roughly 65%. Which segment is this?

A) Proximal convoluted tubule

B) Thick ascending limb

C) Distal convoluted tubule

D) Collecting duct

Which nephron segment reabsorbs approximately 25–30% of filtered calcium?

A) Proximal convoluted tubule

B) Loop of Henle

C) Distal convoluted tubule

D) Collecting tubule

Which nephron segment reabsorbs only about 4–9% of filtered calcium?

A) Proximal convoluted tubule

B) Thin descending limb

C) Distal convoluted tubule

D) Cortical collecting duct

Most calcium reabsorption in the proximal tubule occurs through which pathway?

A) Transcellular active pathway

B) Paracellular passive pathway

C) Vesicular endocytic pathway

D) Hormonal secretory pathway

Calcium reabsorption in the distal convoluted tubule differs from proximal calcium reabsorption because it is primarily what type of process?

A) Passive paracellular transport

B) Active transcellular transport

C) Flow-dependent secretion

D) Protein-bound filtration

What is true?

A) DCT calcium transport requires ATP

B) PCT calcium transport requires ATP

C) Filtered calcium requires ATP

D) Protein binding requires ATP

A trauma patient is hypotensive from blood loss. Which serum calcium change is expected?

A) Hypocalcemia

B) Normocalcemia

C) Hypercalcemia

D) Pseudohypocalcemia

Why can hypotension cause hypercalcemia through renal handling changes?

A) Reduced PCT sodium reabsorption

B) Increased PCT calcium secretion

C) Increased PCT water retention

D) Increased distal calcium excretion

Which acid-base comparison best matches renal calcium excretion?

A) Acidosis reduces, alkalosis promotes

B) Alkalosis promotes, acidosis reduces

C) Alkalosis reduces, acidosis promotes

D) Both reduce calcium excretion

Which site normally reabsorbs most filtered phosphate?

A) Thick ascending limb

B) Distal convoluted tubule

C) Collecting tubule

D) Proximal convoluted tubule

Most phosphate reabsorption in the proximal tubule occurs through which transport mechanism?

A) Sodium-phosphate cotransport

B) Hydrogen-phosphate antiport

C) Potassium-phosphate cotransport

D) Chloride-phosphate exchange

A patient with primary hyperparathyroidism has increased PTH. What happens to renal phosphate reabsorption?

A) It increases markedly

B) It decreases

C) It remains unchanged

D) It shifts distally

A patient with elevated PTH develops hypophosphatemia. Which nephron process is directly suppressed?

A) TAL magnesium transport

B) DCT calcium secretion

C) PCT phosphate reabsorption

D) Collecting duct sodium excretion

A patient has impaired divalent cation reabsorption in the thick ascending limb. Which electrolyte is most affected at its major reabsorptive site?

A) Calcium

B) Phosphate

C) Sodium

D) Magnesium

A patient has an acute increase in GFR. What happens to sodium reabsorption because more sodium reaches the tubules?

A) It decreases

B) It stops

C) It increases

D) It becomes aldosterone-independent

An experiment raises GFR while tubular reabsorptive mechanisms remain intact. Which paired change is expected?

A) Less sodium delivery, less reabsorption

B) More sodium delivery, more reabsorption

C) Less sodium delivery, more reabsorption

D) More sodium delivery, less reabsorption

A patient’s arterial blood pressure rises substantially. Which renal output change is most expected?

A) Increased urine output

B) Reduced urine output

C) Absent urine production

D) Unchanged urine output

A patient receives angiotensin II infusion. Which effect on tubular sodium handling is expected?

A) Decreased sodium reabsorption

B) Increased sodium excretion

C) Increased sodium reabsorption

D) Abolished sodium filtration

Which renal sodium effect helps expand extracellular volume?

A) Reduced sodium filtration

B) Increased sodium reabsorption

C) Increased sodium wasting

D) Blocked sodium transport

A patient with Conn syndrome has high aldosterone but avoids progressive sodium overload. Which mechanism maintains sodium balance?

A) Pressure natriuresis escape

B) ADH escape

C) Tubuloglomerular feedback

D) Aldosterone receptor loss

In Conn syndrome, hypertension eventually limits aldosterone-driven sodium retention. Which sequence best explains this escape?

A) Low BP causes sodium retention

B) High BP causes pressure natriuresis

C) Low aldosterone causes natriuresis

D) High ADH causes potassium wasting

A patient secretes large amounts of ADH and retains water. Which serum sodium-volume pattern is most expected?

A) Hypervolemic hypernatremia

B) Hypovolemic hyponatremia

C) Euvolemic hypernatremia

D) Euvolemic hyponatremia

Why can excessive ADH cause hyponatremia without marked hypervolemia?

A) Potassium retention dilutes sodium

B) Pressure diuresis favors sodium excretion

C) Aldosterone suppresses water retention

D) GFR eliminates all water

A patient with SIADH retains water but maintains near-normal volume. Which paired renal response best explains this?

A) Water loss, sodium retention

B) Sodium loss, pressure diuresis

C) Calcium loss, osmotic diuresis

D) Potassium loss, aldosterone escape

Large amounts of ADH lower serum osmolarity primarily through which immediate effect?

A) Increased sodium filtration

B) Reduced tubular water entry

C) Increased water retention

D) Increased phosphate reabsorption

After a small myocardial infarction, compensatory renal responses help maintain cardiac output. What happens to blood volume?

A) It decreases

B) It increases

C) It remains fixe

d D) It becomes isotonic only

A minor myocardial infarction lowers effective cardiac performance. Which compensatory volume change helps preserve cardiac output?

A) Expanded blood volume

B) Reduced blood volume

C) Reduced plasma proteins

D) Increased free water loss

A patient with nephrotic syndrome loses large amounts of protein in urine. What happens to aldosterone levels?

A) Mildly decreased

B) Unchanged

C) Markedly increased

D) Completely suppressed

Why does nephrotic syndrome strongly increase aldosterone secretion?

A) To increase calcium filtration

B) To preserve blood volume

C) To suppress proteinuria

D) To reduce sodium reabsorption