Renal physiology

Question 1

______ stimulates uric acid reabsorption in PCT

Answer 1

Hypovolemia

Question 2

PAH concentration in a nephron

Answer 2

Minimum in bowman capsule
PCT: ↑ (excreted)
Descending limb: ↑ (water reabsorbed)
Ascending limb and DCT: Remains constant (impermeable to water)

Question 3

Urine pH is chiefly regulated by ______

Answer 3

H+ secretion by late distal and collecting tubules

Question 4

In vomiting and DKA ► Blood Na+ will be?

Answer 4

Decreased (ADH results in more water absorption)
Aldosterone absorbs Na+ but at the same time it also absorbs water with it.
so the combined effect of both these hormones will be ↓Na+ in blood

Question 5

In severe vomiting, total body and serum potassium?

Answer 5

Both ↓ due to GI (vomiting) and renal loss (aldosterone)

Question 6

PAH filtration, secretion, excretion:

Answer 6

Filtration: can’t be saturated as it is freely filtered
Secretion: Saturated (Carrier protein mediated)
Excretion = Filtration + Secretion - Absorption
so, Excretion can never be saturated as it includes filtration too.

Question 7

Patient should be tested for ____ before treatment with EPO

Answer 7

Iron deficiency

Question 8

Dopamine Secreted by

At low doses:

Answer 8

PCT cells, promotes natriuresis.
At low doses; dilates interlobular arteries, afferent arterioles, efferent arterioles →↑RBF, little or no change in GFR.

Question 9

In volume depleted states (vomiting, diarrhea), it is easy to get Na+ abnormalities because

Answer 9

ADH now responds to volume loss, not to high osmolality

Question 10

Why sodium levels are determined by intake and loss of salt in HF patients

Answer 10

Because ADH is triggered by volume censors (non-osmotic) in these patients

Question 11

Hyponatremia with ↑osmolality is seen in

Answer 11

hyperglycemia and mannitol → draws water out of cell → hyponatremia

Question 12

ANP and ATII have same effect on GFR and efferent arterioles, how are they different

Answer 12

ANP: no compensatory Na reabsorption in distal tubule
ATII: compensatory Na reabsorption in PCT and distal tubule

Question 13

Most concentrated part of nephron in the presence and absence of ADH

Answer 13

In ADH absence: lowermost part of loop of henle

In ADH presence: Medullary part of collecting duct

Question 14

ADH binds to V2 receptors on _____ cells

Answer 14

principal

Question 15

_______ are primary mediators of K+ regulation in hyper or hypokalemia

Answer 15

principal and α-intercalated cells of distal and cortical collecting tubules

Question 16

Hypokalemia stimulates reabsorption of K+ via __________

Answer 16

Apically locatedH+/K+ ATPase on α-intecalated cells

Question 17

Water reabsorption in a nephron dependent/independent of hydration status

Answer 17

PCT: >60% (independent of hydration status)
Descending limb: 20% (independent of hydration status)
Upto 20% by late distal and collecting tubules (dependent of hydration status)

Question 18

Most amount of water reabsorbed in a water deprivation state

Answer 18

PCT >60

Question 19

Refractory hypokalemia us seen in ____

Answer 19

Mg deficiency

Normally Mg inhibits K+ excretion by acting on ROMK

Question 20

Hypomagnesimia caused by?

Answer 20

1. GI loss
2. Omeprazole, Foscarnet
3. Renal loss (loop and thiazides)
4. Alcohol abuse
5. Acute Pancreatitis (sponification of Ca/Mg)

Question 21

If alcoholic comes to you in ER, he is most probably deficient in ___ electrolyte

Answer 21

Mg

Question 22

A decrease in both intra and extracellular K+ conc. is seen in

Answer 22

1. Mineralocorticoid excess
2. Chronic GI loss
3. Diuretics

Question 23

A increase in both intra and extracellular K+ conc. is seen in

Answer 23

Chronic renal failure

Question 24

In acute hypercalcemia, nephrogenic diabetes insipidus is due to____

Answer 24

downregulation of aquaporin channels

Question 25

Humoral hypercalcemia of malignancy : PTHrP performs all functions of PTH except

Answer 25

1,25 dihydroxy Vit D production

Question 26

Hypokalmeia symptoms

Answer 26

U waves and flattened T waves on ECG, arrhythmias, muscle cramps, spasm, weakness

Question 27

Hypermagnesimia symptoms

Answer 27

DTRs, lethargy, bradycardia, hypotension, cardiac arrest, hypocalcemia