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USMLE World Missed Questions > Deck IX > Flashcards

Flashcards in Deck IX Deck (30):
1

What is the typical clinical presentation of a patient with IgA nephropathy (or Berger disease)?

Typically affects children and young adults- patients usually present with painless hematuria 2-3 days following an upper respiratory tract infection. Hematuria typically lasts a few days and then returns sporadically every few months.

2

What is seen on immunofluorescent microscopy in a patient with IgA nephropathy?

Prominent IgA deposits in the mesangium which appear like electron dense material.

3

What is IgA nephropathy classified as when it is accompanied by extrarenal symptoms (i.e. abdominal pain, purpuric skin lesions, etc)?

Henoch-Schonlein purpura.

4

What are the typical findings on light microscopy for a patient with poststreptococcal glomeurlonephritis?

Hypercellular glomeruli

5

What presents on urinalysis of a patient with poststreptococcal glomeurlonephritis?

Hematuria, proteinuria, urine RBC casts

6

What laboratory findings are consistent with a diagnosis of poststreptococcal glomeurlonephritis?

Elevated titers of anti-streptococcal antibodies (antistreptolysin O, anti DNase B, anti-cationic proteinase) cryoglobulins, and low C3 concentration.

7

What is the function of Calcineurin?

Essential protein in the activation of IL-2 which promotes growth and differentiation of T cells.

8

What is the mechanism of action of cyclosporine and tacrolimus in immunosuppression?

Inhibition of calcineurin activation.

9

Where is renin synthesized?

Modified smooth muscle (juxtaglomerular) cells of the afferent glomerular arterioles.

10

Renal toxicity associated with amphotericin B requires monitoring for what deficiencies?

Severe hypokalemia and hypomagnesemia

11

Name three factors that promote salt crystalization in urine and two factors that reduce it.

Increased concentrations of calcium, phosphate, oxalate promote stone crystallization; increased citrate and high fluid intake help prevent calculi formation.

12

Addition of what drug to a multidrug regimen to treat class III and IV heart failure patients has been shown to significantly reduce morbidity and mortality?

Spironolactone.

13

What is Primase?

A DNA dependent RNA polymerase that incorporates short RNA primers into replicating DNA.

14

ARBs generate what changes to circulating levels of renin, angiotensin I, angiotensin II, bradykinin, and aldosterone?

Increase renin, angiotensin I, angiotensin II (due to diminished negative feedback mechanisms); decreased aldosterone; no change in bradykinin.

15

In renal dysfunction, hypokalemia and hypomagnesemia reflect what pathology to the kidneys?

Increased distal tubular membrane permeability.

16

What action do ACE inhibitors have on renal arterioles?

ACE inhibitors promote efferent arteriolar dilation causing GFR reductions.

17

What action does angiotensin II have on renal arterioles?

It preferentially constricts efferent arterioles.

18

How do you calculate filtration fraction?

FF= GFR/RPF; GFR can be estimated by creatinine/ inulin clearance; RPF can be measured with PAH clearance.

19

In what forms is acid excreted in the urine?

NH4+, H2PO4- and free H+.

20

Under what conditions does a patient with metabolic acidosis likely also have a superimposed degree of respiratory acidosis and respiratory failure?

When the steady state PaCO2 is higher than what is given in Winter's formula (PaCO2 = [1.5*HCO3-] +8 +/- 2)

21

How does ureteral constriction or obstruction affect GFR and glomerular filtration fraction?

Acutely decreases both GFR and glomerular filtration fraction due the increased hydrostatic pressure proximal to the constriction.

22

What is the difference between PAH and inulin in measuring GFR and RPF?

Inulin is freely filtered and is neither reabsorbed nor secreted by the renal tubules; PAH is freely filtered but is also secreted into the urine by an energy dependent organic acid transporter in the proximal tubule; PAH excreted is thus greater than the filtered load.

23

Which hormones prevent lactation during pregnancy?

High levels of estrogen and progesterone.

24

Where are neurophysins produced and released?

Produced in the paraventricular and supraoptic nuclei of the hypothalamus and are released from axon terminals in the posterior pituitary gland.

25

What are neurophysins?

Proteins involved in the posttranslational processing of oxytocin and vasopressin.

26

What are two possible treatments for paroxysmal supraventricular tachycardia?

Carotid sinus massage, valsalva maneuver

27

How does carotid sinus massage alleviate symptoms of paroxysmal supraventricular tachycardia?

By increasing cardiac parasympathetic tone, it slows the heart rate by slowing conduction through the AV node. Slowed conduction in the AV node abolishes re-entrant circuits causing PSVT.

28

What muscle feedback system maintains muscle force? What system maintains muscle length?

Force is monitored by the Golgi tendon system; the muscle spindle system maintains muscle length.

29

To what stimuli are Golgi Tendon Organs sensitive?

Increases in muscle tension, not sensitive to passive stretch.

30

How is Renal blood flow (RBF) calculated?

RBF= (PAH clearance)/ (1-Hematocrit)